From UC Santa Barbara: “A Quantum Leap”

From UC Santa Barbara

September 16, 2019
James Badham

$25M grant makes UC Santa Barbara home to the nation’s first NSF-funded Quantum Foundry, a center for development of materials and devices for quantum information-based technologies.

Professors Stephen Wilson and Ania Bleszynski Jayich will co-direct the campus’s new Quantum Foundry

We hear a lot these days about the coming quantum revolution. Efforts to understand, develop, and characterize quantum materials — defined broadly as those displaying characteristics that can be explained only by quantum mechanics and not by classical physics — are intensifying.

Researchers around the world are racing to understand these materials and harness their unique qualities to develop revolutionary quantum technologies for quantum computing, communications, sensing, simulation and other quantum technologies not yet imaginable.

This week, UC Santa Barbara stepped to the front of that worldwide research race by being named the site of the nation’s first Quantum Foundry.

Funded by an initial six-year, $25-million grant from the National Science Foundation (NSF), the project, known officially as the UC Santa Barbara NSF Quantum Foundry, will involve 20 faculty members from the campus’s materials, physics, chemistry, mechanical engineering and computer science departments, plus myriad collaborating partners. The new center will be anchored within the California Nanosystems Institute (CNSI) in Elings Hall.

California Nanosystems Institute

The grant provides substantial funding to build equipment and develop tools necessary to the effort. It also supports a multi-front research mission comprising collaborative interdisciplinary projects within a network of university, industry, and national-laboratory partners to create, process, and characterize materials for quantum information science. The Foundry will also develop outreach and educational programs aimed at familiarizing students at all levels with quantum science, creating a new paradigm for training students in the rapidly evolving field of quantum information science and engaging with industrial partners to accelerate development of the coming quantum workforce.

“We are extremely proud that the National Science Foundation has chosen UC Santa Barbara as home to the nation’s first NSF-funded Quantum Foundry,” said Chancellor Henry T. Yang. “The award is a testament to the strength of our University’s interdisciplinary science, particularly in materials, physics and chemistry, which lie at the core of quantum endeavors. It also recognizes our proven track record of working closely with industry to bring technologies to practical application, our state-of-the-art facilities and our educational and outreach programs that are mutually complementary with our research.

“Under the direction of physics professor Ania Bleszynski Jayich and materials professor Stephen Wilson the foundry will provide a collaborative environment for researchers to continue exploring quantum phenomena, designing quantum materials and building instruments and computers based on the basic principles of quantum mechanics,” Yang added.

Said Joseph Incandela, the campus’s vice chancellor for research, “UC Santa Barbara is a natural choice for the NSF quantum materials Foundry. We have outstanding faculty, researchers, and facilities, and a great tradition of multidisciplinary collaboration. Together with our excellent students and close industry partnerships, they have created a dynamic environment where research gets translated into important technologies.”

“Being selected to build and host the nation’s first Quantum Foundry is tremendously exciting and extremely important,” said Rod Alferness, dean of the College of Engineering. “It recognizes the vision and the decades of work that have made UC Santa Barbara a truly world-leading institution worthy of assuming a leadership role in a mission as important as advancing quantum science and the transformative technologies it promises to enable.”

“Advances in quantum science require a highly integrated interdisciplinary approach, because there are many hard challenges that need to be solved on many fronts,” said Bleszynski Jayich. “One of the big ideas behind the Foundry is to take these early theoretical ideas that are just beginning to be experimentally viable and use quantum mechanics to produce technologies that can outperform classical technologies.”

Doing so, however, will require new materials.

“Quantum technologies are fundamentally materials-limited, and there needs to be some sort of leap or evolution of the types of materials we can harness,” noted Wilson. “The Foundry is where we will try to identify and create those materials.”

Research Areas and Infrastructure

Quantum Foundry research will be pursued in three main areas, or “thrusts”:

• Natively Entangled Materials, which relates to identifying and characterizing materials that intrinsically host anyon excitations and long-range entangled states with topological, or structural, protection against decoherence. These include new intrinsic topological superconductors and quantum spin liquids, as well as materials that enable topological quantum computing.

• Interfaced Topological States, in which researchers will seek to create and control protected quantum states in hybrid materials.

• Coherent Quantum Interfaces, where the focus will be on engineering materials having localized quantum states that can be interfaced with various other quantum degrees of freedom (e.g. photons or phonons) for distributing quantum information while retaining robust coherence.

Developing these new materials and assessing their potential for hosting the needed coherent quantum state requires specialized equipment, much of which does not exist yet. A significant portion of the NSF grant is designated to develop such infrastructure, both to purchase required tools and equipment and to fabricate new tools necessary both to grow and characterize the quantum states in the new materials, Wilson said.

UC Santa Barbara’s deep well of shared materials growth and characterization infrastructure was also a factor in securing the grant. The Foundry will leverage existing facilities, such as the large suite of instrumentation shared via the Materials Research Lab and the California Nanosystems Institute, multiple molecular beam epitaxy (MBE) growth chambers (the university has the largest number of MBE apparatuses in academia), unique optical facilities such as the Terahertz Facility, state-of-the-art clean rooms, and others among the more than 300 shared instruments on campus.

Data Science

NSF is keenly interested in both generating and sharing data from materials experiments. “We are going to capture Foundry data and harness it to facilitate discovery,” said Wilson. “The idea is to curate and share data to accelerate discovery at this new frontier of quantum information science.”

Industrial Partners

Industry collaborations are an important part of the Foundry project. UC Santa Barbara’s well-established history of industrial collaboration — it leads all universities in the U.S. in terms of industrial research dollars per capita — and the application focus that allows it to to transition ideas into materials and materials into technologies, was important in receiving the Foundry grant.

Another value of industrial collaboration, Wilson explained, is that often, faculty might be looking at something interesting without being able to visualize how it might be useful in a scaled-up commercial application. “If you have an array of directions you could go, it is essential to have partners to help you visualize those having near-term potential,” he said.

“This is a unique case where industry is highly interested while we are still at the basic-science level,” said Bleszynski Jayich. “There’s a huge industry partnership component to this.”

Among the 10 inaugural industrial partners are Microsoft, Google, IBM, Hewlett Packard Enterprises, HRL, Northrop Grumman, Bruker, SomaLogic, NVision, and Anstrom Science. Microsoft and Google have substantial campus presences already; Microsoft’s Quantum Station Q lab is here, and UC Santa Barbara professor and Google chief scientist John Martinis and a team of his Ph.D. student researchers are working with Google at its Santa Barbara office, adjacent to campus, to develop Google’s quantum computer.

Undergraduate Education

In addition, with approximately 700 students, UC Santa Barbara’s undergraduate physics program is the largest in the U.S. “Many of these students, as well as many undergraduate engineering and chemistry students, are hungry for an education in quantum science, because it’s a fascinating subject that defies our classical intuition, and on top of that, it offers career opportunities. It can’t get much better than that,” Bleszynski Jayich said.

Graduate Education Program

Another major goal of the Foundry project is to integrate quantum science into education and to develop the quantum workforce. The traditional approach to quantum education at the university level has been for students to take physics classes, which are focused on the foundational theory of quantum mechanics.

“But there is an emerging interdisciplinary component of quantum information that people are not being exposed to in that approach,” Wilson explained. “Having input from many overlapping disciplines in both hard science and engineering is required, as are experimental touchstones for trying to understand these phenomena. Student involvement in industry internships and collaborative research with partner companies is important in addressing that.”

“We want to introduce a more practical quantum education,” Bleszynski Jayich added. “Normally you learn quantum mechanics by learning about hydrogen atoms and harmonic oscillators, and it’s all theoretical. That training is still absolutely critical, but now we want to supplement it, leveraging our abilities gained in the past 20 to 30 years to control a quantum system on the single-atom, single-quantum-system level. Students will take lab classes where they can manipulate quantum systems and observe the highly counterintuitive phenomena that don’t make sense in our classical world. And, importantly, they will learn various cutting-edge techniques for maintaining quantum coherence.

“That’s particularly important,” she continued, “because quantum technologies rely on the success of the beautiful, elegant theory of quantum mechanics, but in practice we need unprecedented control over our experimental systems in order to observe and utilize their delicate quantum behavior.”

See the full article here .

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The University of California, Santa Barbara (commonly referred to as UC Santa Barbara or UCSB) is a public research university and one of the 10 general campuses of the University of California system. Founded in 1891 as an independent teachers’ college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system. The university is a comprehensive doctoral university and is organized into five colleges offering 87 undergraduate degrees and 55 graduate degrees. In 2012, UCSB was ranked 41st among “National Universities” and 10th among public universities by U.S. News & World Report. UCSB houses twelve national research centers, including the renowned Kavli Institute for Theoretical Physics.

From Nature: “The bizarre logic of the many-worlds theory”

From Nature

02 September 2019
Robert P. Crease

Originating in the 1950s, the many-worlds theory posits that parallel worlds constantly branch off from each other, moment by moment.Credit: Shutterstock

Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime
Sean M Carroll Oneworld (2019)

At the beginning of Something Deeply Hidden, Sean M Carroll cites the tale of the fox and the grapes from Aesop’s Fables. A hungry fox tries to reach a bunch of grapes dangling from a vine. Finding them beyond his grasp, but refusing to admit failure, the fox declares the grapes to be inedible and turns away. That, Carroll declares, encapsulates how physicists treat the wacky implications of quantum mechanics.

Carroll wants that to stop. The fox can reach the grapes, he argues, with the many-worlds theory. Originated by US physicist Hugh Everett in the late 1950s, this envisions our Universe as just one of numerous parallel worlds that branch off from each other, nanosecond by nanosecond, without intersecting or communicating. (The many-worlds theory differs from the concept of the multiverse, which pictures many self-contained universes in different regions of space-time.)

Six decades on, the theory is one of the most bizarre yet fully logical ideas in human history, growing directly out of the fundamental principles of quantum mechanics without introducing extraneous elements. It has become a staple of popular culture, although the plots of the many films and television series inspired by it invariably flout the theory by relying on contact between the parallel worlds, as in the 2011 movie Another Earth.

In Something Deeply Hidden, Carroll cogently explains the many-worlds theory and its post-Everett evolution, and why our world nevertheless looks the way it does. Largely because of its purely logical character, Carroll calls Everett’s brainchild “the best view of reality we have”.

Catch a wave

Quantum mechanics is the basic framework of modern subatomic physics. It has successfully withstood almost a century of tests, including French physicist Alain Aspect’s experiments confirming entanglement, or action at a distance between certain types of quantum phenomena. In quantum mechanics, the world unfolds through a combination of two basic ingredients. One is a smooth, fully deterministic wave function: a mathematical expression that conveys information about a particle in the form of numerous possibilities for its location and characteristics. The second is something that realizes one of those possibilities and eliminates all the others. Opinions differ about how that happens, but it might be caused by observation of the wave function or by the wave function encountering some part of the classical world.

Many physicists accept this picture at face value in a conceptual kludge known as the Copenhagen interpretation, authored by Niels Bohr and Werner Heisenberg in the 1920s. But the Copenhagen approach is difficult to swallow for several reasons. Among them is the fact that the wave function is unobservable, the predictions are probabilistic and what makes the function collapse is mysterious.

Hugh Everett (second from right) originated the many-worlds theory. (Also pictured, left to right: Charles Misner, Hale Trotter, Niels Bohr and David Harrison.)Credit: Alan Richards/AIP Emilio Segre Visual Archives.

What are we to make of that collapsing wave? The equations work, but what the wave function ‘is’ is the key source of contention in interpreting quantum mechanics. Carroll outlines several alternatives to the Copenhagen interpretation, along with their advantages and disadvantages.

One option, the ‘hidden variables’ approach championed by Albert Einstein and David Bohm, among others, basically states that the wave function is just a temporary fix and that physicists will eventually replace it. Another tack, named quantum Bayesianism, or QBism, by Christopher Fuchs, regards the wave function as essentially subjective. Thus it is merely a guide to what we should believe about the outcome of measurements, rather than a name for a real feature of the subatomic world. Late in his life, Heisenberg proposed that we have to change our notion of reality itself. Reaching back to a concept developed by Aristotle — ‘potency’, as in an acorn’s potential to become an oak tree, given the right context — he suggested that the wave function represents an “intermediate” level of reality.

Carroll argues that the many-worlds theory is the most straightforward approach to understanding quantum mechanics. It accepts the reality of the wave function. In fact, it says that there is one wave function, and only one, for the entire Universe. Further, it states that when an event happens in our world, the other possibilities contained in the wave function do not go away. Instead, new worlds are created, in which each possibility is a reality. The theory’s sheer simplicity and logic within the conceptual framework of quantum mechanics inspire Carroll to call it the “courageous” approach. Don’t worry about those extra worlds, he asserts — we can’t see them, and if the many-worlds theory is true, we won’t notice the difference. The many other worlds are parallel to our own, but so hidden from it that they “might as well be populated by ghosts”.

Branching cats

For physicists, the theory is attractive because it explains many puzzles of quantum mechanics. With Erwin Schrödinger’s thought experiment concerning a dead-and-alive cat, for instance, the cats simply branch into different worlds, leaving just one cat-in-a-box per world. Carroll also shows that the theory offers simpler explanations of certain complex phenomena, such as why black holes emit radiation. Furthermore, the theory might help to develop still-speculative ideas about conundrums such as how to combine quantum mechanics with relativity theory.

Something Deeply Hidden is aimed at non-scientists, with a sidelong glance at physicists still quarrelling over the meaning of quantum mechanics. Carroll brings the reader up to speed on the development of quantum physics from Max Planck to the present, and explains why it is so difficult to interpret, before expounding the many-worlds theory. Dead centre in the book is a “Socratic dialogue” about the theory’s implications. This interlude, between a philosophically sensitive physicist and a scientifically alert philosopher, is designed to sweep away intuitive reservations that non-scientists might have.

Nevertheless, non-scientists might have lingering problems with Carroll’s breezy, largely unexamined ideas about “reality”. Like many physicists, he assumes that reality is whatever a scientific theory says it is. But what gives physicists a lock on this concept, and the right to say that the rest of us (not to mention, say, those in extreme situations such as refugees, soldiers and people who are terminally ill) are living through a less fundamental reality? Could it be that we have to follow Heisenberg’s lead? That is, must we rely on tools for talking about the complexities of reality that philosophers have developed over millennia to explain why the fox has such a tough time reaching those grapes?

What a wacky idea.

See the full article here .

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Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.

From University of Queensland via Science Bulletin: “Physicists mash quantum and gravity and find time, but not as we know it”

From University of Queensland

via

Science Bulletin

August 28, 2019

A University of Queensland-led international team of researchers say they have discovered “a new kind of quantum time order.”

UQ physicist Dr Magdalena Zych said the discovery arose from an experiment the team designed to bring together elements of the two big — but contradictory — physics theories developed in the past century.

“Our proposal sought to discover: what happens when an object massive enough to influence the flow of time is placed in a quantum state?” Dr Zych said.

She said Einstein’s theory described how the presence of a massive object slowed time.

“Imagine two space ships, asked to fire at each other at a specified time while dodging the other’s attack,” she said.

“If either fires too early, it will destroy the other.”

“In Einstein’s theory, a powerful enemy could use the principles of general relativity by placing a massive object — like a planet — closer to one ship to slow the passing of time.”

“Because of the time lag, the ship furthest away from the massive object will fire earlier, destroying the other.”

Dr Zych said the second theory, of quantum mechanics, says any object can be in a state of “superposition”.

“This means it can be found in different states — think Schrodinger’s cat,” she said.

Dr Zych said using the theory of quantum mechanics, if the enemy put the planet into a state of “quantum superposition,” then time also should be disrupted.

“There would be a new way for the order of events to unfold, with neither of the events being first or second — but in a genuine quantum state of being both first and second,” she said.

UQ researcher Dr Fabio Costa said although “a superposition of planets” as described in the paper — may never be possible, technology allowed a simulation of how time works in the quantum world — without using gravity.

“Even if the experiment can never be done, the study is relevant for future technologies,” Dr Costa said.

“We are currently working towards quantum computers that — very simply speaking — could effectively jump through time to perform their operations much more efficiently than devices operating in fixed sequence in time, as we know it in our ‘normal’ world.”

Stevens Institute of Technology and the University of Vienna scientists were co-authors on Bell’s Theorem for Temporal Order, published in Nature Communications.

See the full article here .

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The University of Queensland (UQ) is one of Australia’s leading research and teaching institutions. We strive for excellence through the creation, preservation, transfer and application of knowledge. For more than a century, we have educated and worked with outstanding people to deliver knowledge leadership for a better world.

UQ ranks in the top 50 as measured by the QS World University Rankings and the Performance Ranking of Scientific Papers for World Universities. The University also ranks 52 in the US News Best Global Universities Rankings, 60 in the Times Higher Education World University Rankings and 55 in the Academic Ranking of World Universities.

From University of Rochester: “A ‘new chapter’ in quest for novel quantum materials”

From University of Rochester

August 27, 2019
Bob Marcotte
bmarcotte@ur.rochester.edu

Diamond anvil cells are used to compress and alter the properties of hydrogen rich materials in the lab of assistant professor Ranga Dias. Rochester scientists like Dias are working to uncover the remarkable quantum properties of materials. (University of Rochester photo / J. Adam Fenster)

In an oven, aluminum is remarkable because it can serve as foil over a casserole without ever becoming hot itself.

However, put aluminum in a crucible of extraordinarily high pressure, blast it with high-powered lasers like those at the Laboratory for Laser Energetics, and even more remarkable things happen. Aluminum stops being a metal. It even turns transparent.

University of Rochester Laboratory for Laser Energetics

U Rochester The main amplifiers at the OMEGA EP laser at the University of Rochester’s Laboratory for Laser Energetics

Exactly how and why this occurs is not yet clear. However, LLE scientists and their collaborators say a $4 million grant—from the Quantum Information Science Research for Fusion Energy Sciences (QIS) program within the Department of Energy’s Office of Fusion Energy Science [see the separate article]—will help them better understand and apply the quantum (subatomic) phenomena that cause materials to be transformed at pressures more than a million—even a billion—times the atmospheric pressure on Earth.”

The potential dividends are huge, including:

Superfast quantum computers immune to hacking

IBM iconic image of Quantum computer

Cheap energy created from fusion and delivered over superconducting wires.

PPPL LTX Lithium Tokamak Experiment

A more secure stockpile of nuclear weapons as a deterrent.

A better understanding of how planets and other astronomical bodies form – and even whether some might be habitable.

A size comparison of the planets of the TRAPPIST-1 system, lined up in order of increasing distance from their host star. The planetary surfaces are portrayed with an artist’s impression of their potential surface features, including water, ice, and atmospheres. NASA

“This three-year effort, led by the University of Rochester, will leverage world-class expertise and facilities, and open a new chapter of quantum matter exploration,” says lead investigator Gilbert “Rip” Collins, who heads the University’s high energy density physics program. The project also includes researchers from the University of Illinois at Chicago, the University of Buffalo, the University of Utah, and Howard University and collaborators at the Lawrence Livermore National Laboratory and the University of Edinburgh.

The chief players in quantum mechanics are electrons, protons, photons, and other subatomic particles. Quantum mechanics prescribe only discrete energies or speeds for electrons. These particles can also readily exhibit “duality”—at times acting like distinct particles, at other times taking on wave-like characteristics as well.

However, until recently a lot of their quantum behaviors and properties could be observed only at extremely low, cryogenic temperatures. At low temperatures, the wave-like behavior causes electrons, in layperson terms, “to overlap, become more social and talk more to their neighbors all while occupying discrete states,” says Mohamed Zaghoo, an LLE scientist and project team member. This quantum behavior allows them to transmit energy and can result in superconductive materials.

“The new realization is that you can achieve the same type of ‘quantumness’ of particles if you compress them really, really tightly,” Zaghoo says. This can be achieved in various ways, from blasting the materials with powerful, picoseconds laser bursts to slowly compressing them for days, even months between super-hard industrial diamonds in nanoscale “anvils.”

“Now you can say these materials can only exist under really high pressures, so to duplicate that under normal conditions is still a challenge,” Zaghoo concedes. “But if we are able to understand why materials acquire these exotic behaviors at really high pressures, maybe we can tweak the parameters, and design materials that have these same quantum properties at both higher temperatures and lower pressures. We also hope to build a predictive theory about why and how certain kinds of elements can have these quantum properties and others don’t.”

Here’s an example of why this is an exciting prospect for Zaghoo and his collaborators. Aluminum not only becomes transparent, but also loses its ability to conduct energy at extremely high pressure. If it happens to aluminum, it’s likely it will happen with other metals as well. Chips and transistors rely on metallic oxides to serve as insulating layers. And so, the ability to use high pressure to “uniquely tune” the quantum properties of various metals could lead to “new types of oxides, new types of conductors that make the circuits much more efficient, and lose less heat,” Zaghoo says.

“We would be able to design better electronics.”

And that could help address concerns that Moore’s law—which states the number of transistors in a dense integrated circuit doubles about every two years—cannot continue to be sustained using existing materials and circuitry.

U Rochester a leader in high energy density physics

In addition to creating new materials, a major thrust of the project is to be able to describe and explore those materials in meaningful ways.

“The instrumentation and diagnostics are not there yet,” Zaghoo says. So, part of the proposal is to develop new techniques to “look at these materials and actually see something of substance.”

Much of the project will be done at LLE and at affiliated labs in the University’s Department of Mechanical Engineering. Those labs are led by Ranga Dias, an assistant professor who uses diamond anvil cells to compress hydrogen-rich materials, and Niaz Abdolrahim, an assistant professor who uses computational techniques to understand the deformation of nanoscale metals and other materials.

However, the lab of Russell Hemley at the University of Illinois at Chicago, for example, will also assist the effort to synthesize new materials using diamonds. And Eva Zurek at the SUNY University at Buffalo will be in charge of developing new theoretical models to describe the quantum behaviors that lead to new materials.

“Our scientific team is both diverse and contains top leaders in the fields of high-energy density science, emergent quantum materials, plasmas, condensed matter and computations,” says Collins. “Extensive outreach, workshops and high-profile publications resulting from this work will engage a world-wide community in this extreme quantum revolution.”

Established in 1970 to investigate the interaction of intense radiation with matter, LLE has played a leading role in the quest to achieve nuclear fusion in the lab, with a particular emphasis on inertial confinement fusion.

Two years ago, it launched its high energy density physics initiative under the leadership of Collins, who had previously directed Lawrence Livermore National Laboratory’s Center for High Energy Density Physics.

In addition to drawing upon LLE’s scientists and facilities, the program has also benefited from close collaborations with engineering and science faculty and their students on the University’s nearby River Campus. The synergy has resulted in numerous grants and papers.

See the full article here .

See also the earlier article Department of Energy awards $4 million to University’s Extreme Quantum Team.

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Please help promote STEM in your local schools.

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The University of Rochester is one of the country’s top-tier research universities. Our 158 buildings house more than 200 academic majors, more than 2,000 faculty and instructional staff, and some 10,500 students—approximately half of whom are women.

Learning at the University of Rochester is also on a very personal scale. Rochester remains one of the smallest and most collegiate among top research universities, with smaller classes, a low 10:1 student to teacher ratio, and increased interactions with faculty.

From University of Rochester: “Department of Energy awards $4 million to University’s Extreme Quantum Team”

From University of Rochester

August 27, 2019
Sara Miller
585.275.4128
smiller@ur.rochester.edu

The Laboratory for Laser Energetics of the University of Rochester is a national resource for research and education in science and technology. (University of Rochester photo / Eugene Kowaluk)

Through a competitive national application process, the US Department of Energy (DOE) has awarded the University of Rochester $4 million for research in the growing, multidisciplinary field of Quantum Information Science (QIS), which is viewed as the foundation for the next generation of computing and information processing. This QIS research at Rochester is being supported for three years by the US Department of Energy Office of Science, through its Fusion Energy Sciences Program (FES).

Gilbert “Rip” Collins, professor of mechanical engineering in the Hajim School of Engineering & Applied Sciences and of physics in the School of Arts & Sciences, as well as associate director at the Laboratory for Laser Energetics (LLE), will lead this research with Department of Mechanical Engineering faculty Ranga Dias and Niaz Abdorahim; Ryan Rygg, Danae Polsin, and Mohamed Zaghoo from the LLE; along with distinguished scientists from a number of other institutions across the globe.

“It has been about 100 years since scientists began to discover the exotic properties of quantum matter. Since then, scientists and engineers have exploited such properties by exploring matter at extremely low temperature, where thermal agitation, e.g. the great destroyer of subtle quantum correlations, hides such behavior,” said Collins. “Today we begin to explore a new realm of quantum matter, where atoms are squeezed to such close proximity that quantum properties are no longer subtle, and can persist to very high temperatures. Our team is diverse and contains top leaders in the fields of high-energy density science, emergent quantum materials, plasmas, condensed matter and computations. We will have extensive outreach, workshops and high profile publications, to engage a world-wide community in this extreme quantum revolution.”

“We are very pleased that the DOE has chosen to invest in Rochester’s high-energy density research programs and the groundbreaking fusion research conducted at our Laboratory for Laser Energetics,” said Rob Clark, University provost and senior vice president for research. “The leadership and expertise of our scientists and our state-of-the-art research tools make the University of Rochester an ideal environment to pursue advances in QIS.”

University of Rochester Laboratory for Laser Energetics

U Rochester Laboratory for Laser Energetics

“The Laser Lab is a world-renowned center for groundbreaking research and scientific exploration, and the discoveries that will result from this new work at the lab are no exception,” said US Senate Minority Leader Charles E. Schumer. “This new DOE investment affirms the LLE’s international reputation for scientific innovation and underscores my continued push to keep the lab and its more than 350 employees on the job.”

US Representative Joe Morelle said: “The Laboratory for Laser Energetics continues to cement its place as a world-class institution and leader in cutting edge scientific research. This substantial award will allow the University of Rochester to leverage this unique facility to explore new realms of quantum matter and phenomena, making discoveries with fascinating potential future applications right here in Rochester. I am grateful to DOE for their investment in the future of our community and congratulate the University of Rochester on this exciting award.”

LLE Director Mike Campbell said: “We are very pleased that the DOE has recognized the quality and the potential for advancing our knowledge of the quantum behavior of matter at the extreme conditions that we can produce with these laser facilities. This also shows how the different offices in the DOE effectively work together. The facilities and capabilities provided by National Nuclear Security Administration (NNSA) at LLE will enable cutting edge science funded by the DOE Office of Fusion energy Sciences.”

This “Extreme Quantum Team” will focus their research on tuning the energy density of matter into a high-energy-density (HED) quantum regime to understand extremes of quantum matter behavior, properties and phenomena. Since the early days of quantum mechanics, the realm of quantum matter has been limited to low temperatures, restricting the breadth of quantum phenomena that could be exploited and explored. The project will take advantage of new developments in HED science that enable the controlled manipulation of pressure, temperature and composition, opening the way to revolutionary quantum states of matter. For example, this team will use compression experiments to tune the distance between atoms thereby unlocking a new quantum behavior at unprecedentedly high temperatures, transferring quantum phenomena to the macroscale, and opening the potential for hot superconductors, superconducting-superfluid plasma, transparent aluminum, insulating plasma and potentially more.

The call for applications for this QIS award asked for proposals that can have a transformative impact on the FES mission, which is to expand the fundamental understanding of matter at very high temperatures and densities and to build the scientific foundation needed to develop a fusion energy source. The FES pursues scientific opportunities and grand challenges in high energy density plasma science to better understand our universe and to enhance national security and economic competitiveness. FES is also focused on increasing the fundamental understanding of basic plasma science to create opportunities for a broader range of science-based applications.

See the full article here .

See also the later article University of Rochester: A ‘new chapter’ in quest for novel quantum materials

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The University of Rochester is one of the country’s top-tier research universities. Our 158 buildings house more than 200 academic majors, more than 2,000 faculty and instructional staff, and some 10,500 students—approximately half of whom are women.

Learning at the University of Rochester is also on a very personal scale. Rochester remains one of the smallest and most collegiate among top research universities, with smaller classes, a low 10:1 student to teacher ratio, and increased interactions with faculty.

From Symmetry: “Gravity’s Waterfall”

From Symmetry

07/30/19
Daniel Garisto

Physicists are using analog black holes to better understand gravity.

Illustration by Sandbox Studio, Chicago with Ariel Davis

A0620-00, a binary star system 3300 light-years away, holds a dark secret: One of its stars isn’t a star at all, but a black hole. As far as we know, this is the black hole closest to our planet. Astronomers know it’s there only because its partner star appears to be dancing alone, pulled along by an invisible lead.

In recent years, scientists have found ways to study black holes, listening to the gravitational waves they unleash when they collide, and even creating an image of one by combining information from radio telescopes around the world.

MIT /Caltech Advanced aLigo

VIRGO Collaboration

But our knowledge of black holes remains limited. No one will ever be able to test a real one in a lab, and with current technology, it would take about 50 million years for a probe to reach A0620-00.

So scientists are figuring out how to make do with substitutes—analogs to black holes that may hold answers to mysteries about gravity and quantum mechanics.

Building black hole models

In 1972, William “Bill” Unruh, a physicist at the University of British Columbia, Vancouver, connected gravity to fluid dynamics in an analogy: “Imagine that you are a blind fish, and are also a physicist, living in a river,” Unruh wrote.

Along Unruh’s imaginary river, a waterfall plunges at a supersonic speed—faster than the speed of sound in water. What happens if a fellow fish goes over the falls? You, a blind fish, cannot know; you will never hear it scream because the waterfall will drag the sound down faster than it can travel up.

Unruh used this piscine drama to explain a property of black holes: Like sound that passes over the edge of the supersonic waterfall, light that crosses the horizon of a black hole cannot escape.

The analogy turned out to be more accurate than Unruh initially thought. Eight years later, in 1980, he realized that the equations of motion for sound in the waterfall analogy were identical to those describing light at the horizon of a black hole.

At the time, his research drew little attention—it was cited just four times in the decade after it was published. But in the ’90s, Unruh’s work was rediscovered as physicists began probing gravity theoretically and experimentally with analog models.

Today, physicists use everything from water to exotic ultracold states of matter to mimic black holes. Proponents of the analogs say that these models have confirmed theoretical predictions about black holes. But many physicists still doubt that analogs can predict what happens where gravity warps spacetime so violently.

Black holes were first theorized in 1784, by English clergyman and astronomer John Michell, who calculated that for a large enough star, “all light emitted from such a body would be made to return towards it, by its own proper gravity.”

The idea was mostly put aside until the 20th century, when Einstein’s general theory of relativity overturned the paradigm of Newtonian gravity. Luminaries like Karl Schwarzchild, Subrahmanyan Chandrasekhar and John Archibald Wheeler developed theory about these monsters from which nothing could escape. But in 1974, a young physicist named Stephen Hawking revolutionized the field by proposing that that something could, in fact, escape from a black hole.

Due to random quantum fluctuations in the fabric of spacetime, pairs of virtual particles and antiparticles pop into existence all the time, throughout the universe. Most of the time, these pairs annihilate instantly, disappearing back into the void. But, Hawking theorized, the horizon of a black hole could separate a pair: One particle would be sucked in, while the other would zoom away as a now real particle.

Because of a mathematical quirk in Hawking radiation, swallowed virtual particles effectively have negative energy. Black holes that gobble up these particles shrink. To an observer, Hawking radiation would look a lot like a black hole spitting up what it swallowed and getting smaller.
—
However, Hawking radiation is random and carries no information about the inside of a black hole—remember that the emitted particle comes from just outside the horizon. This creates a paradox: Quantum mechanics rests on the premise that information is never destroyed, but if particles emitted as Hawking radiation are truly random, information would be lost forever.

Most physicists believe that black holes don’t truly destroy information and that information is preserved in Hawking radiation, but that conjecture may be impossible to test directly. “The temperature of Hawking radiation is very small—it’s much smaller than the background radiation of the universe,” says Hai Son Nguyen, a physicist at the Institute of Nanotechnology of Lyon. “That’s why we will never be able to observe Hawking radiation from a real black hole.”

What about something that behaved a lot like a black hole? In his 1980 paper, Unruh calculated that phonons—quantum units of sound analogous to photons, quantum units of light—would be the Hawking radiation emitted from his analog black hole.

Unruh was initially bleak about the prospects of actually making such a measurement, calling it “an extremely slim possibility.” But as more physicists joined Unruh in theorizing about analogs to black holes in the ’90s, the possibility of measuring Hawking radiation became a difficult, but achievable goal.

Over the waterfall

There are many different analog models of black holes, but they all have one aspect in common: a horizon. Mathematically, horizons are defined as the boundary beyond which events cannot escape—like the edge of Unruh’s waterfall. Because they can separate pairs of particles, any horizon creates a form of Hawking radiation.

“Understanding of the phenomenology associated with the presence of horizons in different analog systems provides hints about phenomena that might also be present in the gravitational realm,” writes Carlos Barceló, a theoretical physicist at the Astrophysical Institute of Andalucia.

Often, it’s useful to start with a simple analog like water, says Silke Weinfurtner, a physicist at the University of Nottingham. It’s possible to create a horizon by running water quickly enough over an obstacle; if the conditions are just right, surface waves are thwarted at the obstacle.

But to properly measure the smallest—quantum-level—effects of a black hole, you need a quantum analog. Bose-Einstein condensates, or BECs, are typically ultracold gases like rubidium that are ruled by quantum effects odd enough to qualify them as another state of matter. Subtle quantum effects like Hawking radiation hidden by the noise present in normal fluids become apparent in BECs.

Analog black holes can even use light as a fluid. The fluid is made of quasiparticles called polaritons, which are the collective state of a photon that couples to an electric field. Enough polaritons behave as a quantum fluid of light. So when the flow of polaritons goes faster than the speed of sound in the polariton fluid, just like Unruh’s waterfall, a horizon forms. Hawking radiation from this fluid of light still comes in the form of phonons.

Some black hole analogs are “optical” because their Hawking radiation comes in photons. In optical fibers—like the type we send data through—intense laser pulses can create a horizon. The pulse changes the physical properties of the fiber, slowing down the speed of light within the fiber. This makes the leading edge of the pulse a horizon: Slowed light cannot escape past the pulse any more than sound can escape up out of Unruh’s waterfall.

To date, though, experimental evidence of Hawking radiation in any of these analogs has been lacking in support—with one exception.

In May, Jeff Steinhauer published his latest paper, with the strongest evidence yet for Hawking radiation. Steinhauer, a physicist at the Technion in Haifa, Israel, has been working on the problem for over a decade, chipping away relentlessly at the extremely difficult experimental task, largely on his own.

Focusing a laser on rubidium gas, a BEC, Steinhauer created a high-energy region. Particles move from high-energy regions to low-energy regions, so the rubidium gas wanted to escape the laser. The edge of the laser here functioned as the horizon for the rubidium gas, similar to a waterfall that it could go over but not come back up. Steinhauer used the set-up to study the Hawking radiation resulting from quantum fluctuations separated by the horizon.

The temperature of Hawking radiation—how much energy the emitted phonons have, in this case—depends on the slope of the horizon, or waterfall. The steeper it is, the higher the energy of the radiation. This is why Hawking radiation is low temperature for a black hole: A weak force like gravity doesn’t make for a steep horizon.

By measuring the slope, and then separately measuring the energy of radiated phonons, Steinhauer was able to get corroboration for his data.

Previous experiments from Steinhauer and others have claimed to find Hawking radiation [PhysicsWorld], but have lacked the rigor of this latest result. This time, Steinhauer and some other physicists believe he has observed Hawking radiation.

“I think we verified Hawking’s calculation,” Steinhauer says. “He had a calculation with certain assumptions and approximations, and we have the same approximations, and so mathematically it’s equivalent.”

However, Steinhauer points out, it’s quite possible that Hawking radiation works differently for black holes because of quantum gravity. Critics also claim phonons may not be perfect analogs to photons.

Many physicists who work on quantum gravity are dismissive of the latest results, according to reporting in Quanta.

Weinfurtner acknowledges the criticism and agrees that analogs cannot strictly prove anything about black holes. But to physicists working on analogs, the facsimiles of black holes are already worthwhile. “What we’re doing is already on its own really interesting,” she says. “We’re deepening our understanding of the analog gravity systems, and the hope is that such experiments stimulate new theoretical black hole studies.”

See the full article here .

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Symmetry is a joint Fermilab/SLAC publication.

From Stanford University: “Stanford physicists count sound particles with quantum microphone”

From Stanford University

July 24, 2019
Ker Than

A device that eavesdrops on the quantum whispers of atoms could form the basis of a new type of quantum computer.

Artist’s impression of an array of nanomechanical resonators designed to generate and trap sound particles, or phonons. The mechanical motions of the trapped phonons are sensed by a qubit detector, which shifts its frequency depending on the number of phonons in a resonator. Different phonon numbers are visible as distinct peaks in the qubit spectrum, which are shown schematically behind the resonators. (Image credit: Wentao Jiang)

Stanford physicists have developed a “quantum microphone” so sensitive that it can measure individual particles of sound, called phonons.

The device, which is detailed July 24 in the journal Nature, could eventually lead to smaller, more efficient quantum computers that operate by manipulating sound rather than light.

“We expect this device to allow new types of quantum sensors, transducers and storage devices for future quantum machines,” said study leader Amir Safavi-Naeini, an assistant professor of applied physics at Stanford’s School of Humanities and Sciences.

Quantum of motion

First proposed by Albert Einstein in 1907, phonons are packets of vibrational energy emitted by jittery atoms. These indivisible packets, or quanta, of motion manifest as sound or heat, depending on their frequencies.

Like photons, which are the quantum carriers of light, phonons are quantized, meaning their vibrational energies are restricted to discrete values – similar to how a staircase is composed of distinct steps.

“Sound has this granularity that we don’t normally experience,” Safavi-Naeini said. “Sound, at the quantum level, crackles.”

The energy of a mechanical system can be represented as different “Fock” states – 0, 1, 2, and so on – based on the number of phonons it generates. For example, a “1 Fock state” consist of one phonon of a particular energy, a “2 Fock state” consists of two phonons with the same energy, and so on. Higher phonon states correspond to louder sounds.

Until now, scientists have been unable to measure phonon states in engineered structures directly because the energy differences between states – in the staircase analogy, the spacing between steps – is vanishingly small. “One phonon corresponds to an energy ten trillion trillion times smaller than the energy required to keep a lightbulb on for one second,” said graduate student Patricio Arrangoiz-Arriola, a co-first author of the study.

To address this issue, the Stanford team engineered the world’s most sensitive microphone – one that exploits quantum principles to eavesdrop on the whispers of atoms.

In an ordinary microphone, incoming sound waves jiggle an internal membrane, and this physical displacement is converted into a measurable voltage. This approach doesn’t work for detecting individual phonons because, according to the Heisenberg uncertainty principle, a quantum object’s position can’t be precisely known without changing it.

“If you tried to measure the number of phonons with a regular microphone, the act of measurement injects energy into the system that masks the very energy that you’re trying to measure,” Safavi-Naeini said.

Instead, the physicists devised a way to measure Fock states – and thus, the number of phonons – in sound waves directly. “Quantum mechanics tells us that position and momentum can’t be known precisely – but it says no such thing about energy,” Safavi-Naeini said. “Energy can be known with infinite precision.”

Singing qubits

The quantum microphone the group developed consists of a series of supercooled nanomechanical resonators, so small that they are visible only through an electron microscope. The resonators are coupled to a superconducting circuit that contains electron pairs that move around without resistance. The circuit forms a quantum bit, or qubit, that can exist in two states at once and has a natural frequency, which can be read electronically. When the mechanical resonators vibrate like a drumhead, they generate phonons in different states.

“The resonators are formed from periodic structures that act like mirrors for sound. By introducing a defect into these artificial lattices, we can trap the phonons in the middle of the structures,” Arrangoiz-Arriola said.

Like unruly inmates, the trapped phonons rattle the walls of their prisons, and these mechanical motions are conveyed to the qubit by ultra-thin wires. “The qubit’s sensitivity to displacement is especially strong when the frequencies of the qubit and the resonators are nearly the same,” said joint first-author Alex Wollack, also a graduate student at Stanford.

However, by detuning the system so that the qubit and the resonators vibrate at very different frequencies, the researchers weakened this mechanical connection and triggered a type of quantum interaction, known as a dispersive interaction, that directly links the qubit to the phonons.

This bond causes the frequency of the qubit to shift in proportion to the number of phonons in the resonators. By measuring the qubit’s changes in tune, the researchers could determine the quantized energy levels of the vibrating resonators – effectively resolving the phonons themselves.

“Different phonon energy levels appear as distinct peaks in the qubit spectrum,” Safavi-Naeini said. “These peaks correspond to Fock states of 0, 1, 2 and so on. These multiple peaks had never been seen before.”

Mechanical quantum mechanical

Mastering the ability to precisely generate and detect phonons could help pave the way for new kinds of quantum devices that are able to store and retrieve information encoded as particles of sound or that can convert seamlessly between optical and mechanical signals.

Such devices could conceivably be made more compact and efficient than quantum machines that use photons, since phonons are easier to manipulate and have wavelengths that are thousands of times smaller than light particles.

“Right now, people are using photons to encode these states. We want to use phonons, which brings with it a lot of advantages,” Safavi-Naeini said. “Our device is an important step toward making a ‘mechanical quantum mechanical’ computer.”

Other Stanford co-authors include graduate students Zhaoyou Wang, Wentao Jiang, Timothy McKenna and Jeremy Witmer, and postdoctoral researchers Marek Pechal and Raphël Van Laer.

The research was funded by the David and Lucile Packard Fellowship, the Stanford University Terman Fellowship and the U.S. Office of Naval Research.

See the full article here .

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Stanford University campus. No image credit

Stanford University

Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

From insideHPC: “Supercomputing Complex Materials with QMCPACK”

From insideHPC

July 21, 2019

In this special guest feature, Scott Gibson from the Exascale Computing Project writes that computer simulations based on quantum mechanics are getting a boost through QMCPACK.

The theory of quantum mechanics underlies explorations of the behavior of matter and energy in the atomic and subatomic realms. Computer simulations based on quantum mechanics are consequently essential in designing, optimizing, and understanding the properties of materials that have, for example, unusual magnetic or electrical properties. Such materials would have potential for use in highly energy-efficient electrical systems and faster, more capable electronic devices that could vastly improve our quality of life.

Quantum mechanics-based simulation methods render robust data by describing materials in a truly first-principles manner. This means they calculate electronic structure in the most basic terms and thus can allow speculative study of systems of materials without reference to experiment, unless researchers choose to add parameters. The quantum Monte Carlo (QMC) family of these approaches is capable of delivering the most highly accurate calculations of complex materials without biasing the results of a property of interest.

An effort within the US Department of Energy’s Exascale Computing Project (ECP) is developing a QMC methods software named QMCPACK to find, predict, and control materials and properties at the quantum level. The ultimate aim is to achieve an unprecedented and systematically improvable accuracy by leveraging the memory and power capabilities of the forthcoming exascale computing systems.

Greater Accuracy, Versatility, and Performance

One of the primary objectives of the QMCPACK project is to reduce errors in calculations so that predictions concerning complex materials can be made with greater assurance.

“We would like to be able to tell our colleagues in experimentation that we have confidence that a certain short list of materials is going to have all the properties that we think they will,” said Paul Kent of Oak Ridge National Laboratory and principal investigator of QMCPACK. “Many ways of cross-checking calculations with experimental data exist today, but we’d like to go further and make predictions where there aren’t experiments yet, such as a new material or where taking a measurement is difficult—for example, in conditions of high pressure or under an intense magnetic field.”

The methods the QMCPACK team is developing are fully atomistic and material specific. This refers to having the capability to address all of the atoms in the material—whether it be silver, carbon, cerium, or oxygen, for example—compared with more simplified lattice model calculations where the full details of the atoms are not included.

The team’s current activities are restricted to simpler, bulk-like materials; but exascale computing is expected to greatly widen the range of possibilities.

“At exascale not only the increase in compute power but also important changes in the memory on the machines will enable us to explore material defects and interfaces, more-complex materials, and many different elements,” Kent said.

With the software engineering, design, and computational aspects of delivering the science as the main focus, the project plans to improve QMCPACK’s performance by at least 50x. Based on experimentation using a mini-app version of the software, and incorporating new algorithms, the team achieved a 37x improvement on the pre-exascale Summit supercomputer versus the Titan system.

ORNL IBM AC922 SUMMIT supercomputer, No.1 on the TOP500. Credit: Carlos Jones, Oak Ridge National Laboratory/U.S. Dept. of Energy

ORNL Cray XK7 Titan Supercomputer, once the fastest in the world, to be decommissioned

One Robust Code

“We’re taking the lessons we’ve learned from developing the mini app and this proof of concept, the 37x, to update the design of the main application to support this high efficiency, high performance for a range of problem sizes,” Kent said. “What’s crucial for us is that we can move to a single version of the code with no internal forks, to have one source supporting all architectures. We will use all the lessons we’ve learned with experimentation to create one version where everything will work everywhere—then it’s just a matter of how fast. Moreover, in the future we will be able to optimize. But at least we won’t have a gap in the feature matrix, and the student who is running QMCPACK will always have all features work.”

As an open-source and openly developed product, QMCPACK is improving via the help of many contributors. The QMCPACK team recently published the master citation paper for the software’s code; the publication has 48 authors with a variety of affiliations.

“Developing these large science codes is an enormous effort,” Kent said. “QMCPACK has contributors from ECP researchers, but it also has many past developers. For example, a great deal of development was done for the Knights Landing processor on the Theta supercomputer with Intel. This doubled the performance on all CPU-like architectures.”

ANL ALCF Theta Cray XC40 supercomputer

A Synergistic Team

The QMCPACK project’s collaborative team draws talent from Argonne, Lawrence Livermore, Oak Ridge, and Sandia National Laboratories.

It also benefits from collaborations with Intel and NVIDIA.

The composition of the staff is nearly equally divided between scientific domain specialists and people centered on the software engineering and computer science aspects.

“Bringing all of this expertise together through ECP is what has allowed us to perform the design study, reach the 37x, and improve the architecture,” Kent said. “All the materials we work with have to be doped, which means incorporating additional elements in them. We can’t run those simulations on Titan but are beginning to do so on Summit with improvements we have made as part of our ECP project. We are really looking forward to the opportunities that will open up when the exascale systems are available.”

See the full article here .

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Founded on December 28, 2006, insideHPC is a blog that distills news and events in the world of HPC and presents them in bite-sized nuggets of helpfulness as a resource for supercomputing professionals. As one reader said, we’re sifting through all the news so you don’t have to!

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From University of Glasgow via Science Alert: “Scientists Just Unveiled The First-Ever Photo of Quantum Entanglement”

From University of Glasgow

via

Science Alert

13 JUL 2019
FIONA MACDONALD

(University of Glasgow)

In an incredible first, scientists have captured the world’s first actual photo of quantum entanglement – a phenomenon so strange Einstein famously described it as ‘spooky action at a distance’.

The image was captured by physicists at the University of Glasgow in Scotland, and it’s so breathtaking we can’t stop staring.

It might not look like much, but just stop and think about it for a second: this fuzzy grey image is the first time we’ve seen the particle interaction that underpins the strange science of quantum mechanics and forms the basis of quantum computing.

Quantum entanglement occurs when two particles become inextricably linked, and whatever happens to one immediately affects the other, regardless of how far apart they are. Hence the ‘spooky action at a distance’ description.

This particular photo shows entanglement between two photons – two particles of light. They’re interacting and for a brief moment sharing physical states.

Paul-Antoine Moreau, first author on the paper where the image was unveiled, told the BBC the image was “an elegant demonstration of a fundamental property of nature”.

To capture the incredible photo, Moreau and a team of physicists created a system that blasted out streams of entangled photons at what they described as ‘non-conventional objects’.

The experiment actually involved capturing four images of the photons under four different phase transitions. You can see the full image below:

(Moreau et al., Science Advances, 2019)

What you’re looking at here is actually a composite of multiple images of the photons as they go through a series of four phase transitions.

Basically, the physicists split the entangled photons up and ran one beam through a liquid crystal material known as β-Barium Borate, triggering four phase transitions.

At the same time they captured photos of the entangled pair going through the same phase transitions, even though it hadn’t passed through the liquid crystal.

You can see the setup below, the entangled beam of photons comes from the bottom left, one half of the entangled pair splits to the left and passes through the four phase filters. The others that go straight ahead didn’t go through the filters, but underwent the same phase changes.

(Moreau et al., Science Advances, 2019)

The camera was able to capture images of these at the same time, showing that they’d both shifted the same way despite being split. In other words, they were entangled.

While Einstein made quantum entanglement famous, the late physicist John Stewart Bell helped define quantum entanglement and established a test known as ‘Bell inequality’. Basically, if you can break Bell inequality, you can confirm true quantum entanglement.

“Here, we report an experiment demonstrating the violation of a Bell inequality within observed images,” the team write in Science Advances.

“This result both opens the way to new quantum imaging schemes … and suggests promise for quantum information schemes based on spatial variables.”

The research was published in Science Advances.

See the full article here .

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The University of Glasgow (Scottish Gaelic: Oilthigh Ghlaschu, Latin: Universitas Glasguensis) is the fourth oldest university in the English-speaking world and one of Scotland’s four ancient universities. It was founded in 1451. Along with the University of Edinburgh, the University was part of the Scottish Enlightenment during the 18th century. It is currently a member of Universitas 21, the international network of research universities, and the Russell Group.

In common with universities of the pre-modern era, Glasgow originally educated students primarily from wealthy backgrounds, however it became a pioneer[citation needed] in British higher education in the 19th century by also providing for the needs of students from the growing urban and commercial middle class. Glasgow University served all of these students by preparing them for professions: the law, medicine, civil service, teaching, and the church. It also trained smaller but growing numbers for careers in science and engineering.[4]

Originally located in the city’s High Street, since 1870 the main University campus has been located at Gilmorehill in the West End of the city.[5] Additionally, a number of university buildings are located elsewhere, such as the University Marine Biological Station Millport on the Island of Cumbrae in the Firth of Clyde and the Crichton Campus in Dumfries.

Alumni or former staff of the University include philosopher Francis Hutcheson, engineer James Watt, philosopher and economist Adam Smith, physicist Lord Kelvin, surgeon Joseph Lister, 1st Baron Lister, seven Nobel laureates, and two British Prime Ministers.

From Argonne Leadership Computing Facility: “Predicting material properties with quantum Monte Carlo”

News from Argonne National Laboratory

From Argonne Leadership Computing Facility

July 9, 2019
Nils Heinonen

For one of their efforts, the team used diffusion Monte Carlo to compute how doping affects the energetics of nickel oxide. Their simulations revealed the spin density difference between bulks of potassium-doped nickel oxide and pure nickel oxide, showing the effects of substituting a potassium atom (center atom) for a nickel atom on the spin density of the bulk. Credit: Anouar Benali, Olle Heinonen, Joseph A. Insley, and Hyeondeok Shin, Argonne National Laboratory.

Recent advances in quantum Monte Carlo (QMC) methods have the potential to revolutionize computational materials science, a discipline traditionally driven by density functional theory (DFT). While DFT—an approach that uses quantum-mechanical modeling to examine the electronic structure of complex systems—provides convenience to its practitioners and has unquestionably yielded a great many successes throughout the decades since its formulation, it is not without shortcomings, which have placed a ceiling on the possibilities of materials discovery. QMC is poised to break this ceiling.

The key challenge is to solve the quantum many-body problem accurately and reliably enough for a given material. QMC solves these problems via stochastic sampling—that is, by using random numbers to sample all possible solutions. The use of stochastic methods allows the full many-body problem to be treated while circumventing large approximations. Compared to traditional methods, they offer extraordinary potential accuracy, strong suitability for high-performance computing, and—with few known sources of systematic error—transparency. For example, QMC satisfies a mathematical principle that allows it to set a bound for a given system’s ground state energy (the lowest-energy, most stable state).

QMC’s accurate treatment of quantum mechanics is very computationally demanding, necessitating the use of leadership-class computational resources and thus limiting its application. Access to the computing systems at the Argonne Leadership Computing Facility (ALCF) and the Oak Ridge Leadership Computing Facility (OLCF)—U.S. Department of Energy (DOE) Office of Science User Facilities—has enabled a team of researchers led by Paul Kent of Oak Ridge National Laboratory (ORNL) to meet the steep demands posed by QMC. Supported by DOE’s Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program, the team’s goal is to simulate promising materials that elude DFT’s investigative and predictive powers.

To conduct their work, the researchers employ QMCPACK, an open-source QMC code developed by the team. It is written specifically for high-performance computers and runs on all the DOE machines. It has been run at the ALCF since 2011.

Functional materials

The team’s efforts are focused on studies of materials combining transition metal elements with oxygen. Many of these transition metal oxides are functional materials that have striking and useful properties. Small perturbations in the make-up or structure of these materials can cause them to switch from metallic to insulating, and greatly change their magnetic properties and ability to host and transport other atoms. Such attributes make the materials useful for technological applications while posing fundamental scientific questions about how these properties arise.

The computational challenge has been to simulate the materials with sufficient accuracy: the materials’ properties are sensitive to small changes due to complex quantum mechanical interactions, which make them very difficult to model.

The computational performance and large memory of the ALCF’s Theta system have been particularly helpful to the team. Theta’s storage capacity has enabled studies of material changes caused by small perturbations such as additional elements or vacancies. Over three years the team developed a new technique to more efficiently store the quantum mechanical wavefunctions used by QMC, greatly increasing the range of materials that could be run on Theta.

ANL ALCF Theta Cray XC40 supercomputer

Experimental Validation

Kent noted that experimental validation is a key component of the INCITE project. “The team is leveraging facilities located at Argonne and Oak Ridge National Laboratories to grow high-quality thin films of transition-metal oxides,” he said, including vanadium oxide (VO2) and variants of nickel oxide (NiO) that have been modified with other compounds.

For VO2, the team combined atomic force microscopy, Kelvin probe force microscopy, and time-of-flight secondary ion mass spectroscopy on VO2 grown at ORNL’s Center for Nanophase Materials Science (CNMS) to demonstrate how oxygen vacancies suppress the transition from metallic to insulating VO2. A combination of QMC, dynamical mean field theory, and DFT modeling was deployed to identify the mechanism by which this phenomenon occurs: oxygen vacancies leave positively charged holes that are localized around the vacancy site and end up distorting the structure of certain vanadium orbitals.

For NiO, the challenge was to understand how a small quantity of dopant atoms, in this case potassium, modifies the structure and optical properties. Molecular beam epitaxy at Argonne’s Materials Science Division was used to create high quality films that were then probed via techniques such as x-ray scattering and x-ray absorption spectroscopy at Argonne’s Advanced Photon Source (APS) [below] for direct comparison with computational results. These experimental results were subsequently compared against computational models employing QMC and DFT. The APS and CNMS are DOE Office of Science User Facilities.

So far the team has been able to compute, understand, and experimentally validate how the band gap of materials containing a single transition metal element varies with composition. Band gaps determine a material’s usefulness as a semiconductor—a substance that can alternately conduct or cease the flow of electricity (which is important for building electronic sensors or devices). The next steps of the study will be to tackle more complex materials, with additional elements and more subtle magnetic properties. While more challenging, these materials could lead to greater discoveries.

New chemistry applications

Many of the features that make QMC attractive for materials also make it attractive for chemistry applications. An outside colleague—quantum chemist Kieron Burke of the University of California, Irvine—provided the impetus for a paper published in Journal of Chemical Theory and Computation. Burke approached the team’s collaborators with a problem he had encountered while trying to formulate a new method for DFT. Moving forward with his attempt required benchmarks against which to test his method’s accuracy. As QMC was the only means by which sufficiently precise benchmarks could be obtained, the team produced a series of calculations for him.

The reputed gold standard for many-body system numerical techniques in quantum chemistry is known as coupled cluster theory. While it is extremely accurate for many molecules, some are so strongly correlated quantum-mechanically that they can be thought of as existing in a superposition of quantum states. The conventional coupled cluster method cannot handle something so complicated. Co-principal investigator Anouar Benali, a computational scientist at the ALCF and Argonne’s Computational Sciences Division, spent some three years collaborating on efforts to expand QMC’s capability so as to include both low-cost and highly efficient support for these states that will in future also be needed for materials problems. Performing analysis on the system for which Burke needed benchmarks required this superposition support; he verified the results of his newly developed DFT approach against the calculations generated with Benali’s QMC expansion. They were in close agreement with each other, but not with the results conventional coupled cluster had generated—which, for one particular compound, contained significant errors.

“This collaboration and its results have therefore identified a potential new area of research for the team and QMC,” Kent said. “That is, tackling challenging quantum chemical problems.”

The research was supported by DOE’s Office of Science. ALCF and OLCF computing time and resources were allocated through the INCITE program.

See the full article here .

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Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science. For more visit http://www.anl.gov.

About ALCF
The Argonne Leadership Computing Facility’s (ALCF) mission is to accelerate major scientific discoveries and engineering breakthroughs for humanity by designing and providing world-leading computing facilities in partnership with the computational science community.

We help researchers solve some of the world’s largest and most complex problems with our unique combination of supercomputing resources and expertise.

ALCF projects cover many scientific disciplines, ranging from chemistry and biology to physics and materials science. Examples include modeling and simulation efforts to:

Discover new materials for batteries
Predict the impacts of global climate change
Unravel the origins of the universe
Develop renewable energy technologies

Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science