From Quanta: “Quantum Leaps, Long Assumed to Be Instantaneous, Take Time”

Quanta Magazine
From Quanta Magazine

June 5, 2019
Philip Ball

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A quantum leap is a rapidly gradual process. Quanta Magazine; source: qoncha

When quantum mechanics was first developed a century ago as a theory for understanding the atomic-scale world, one of its key concepts was so radical, bold and counter-intuitive that it passed into popular language: the “quantum leap.” Purists might object that the common habit of applying this term to a big change misses the point that jumps between two quantum states are typically tiny, which is precisely why they weren’t noticed sooner. But the real point is that they’re sudden. So sudden, in fact, that many of the pioneers of quantum mechanics assumed they were instantaneous.

A new experiment [Nature] shows that they aren’t. By making a kind of high-speed movie of a quantum leap, the work reveals that the process is as gradual as the melting of a snowman in the sun. “If we can measure a quantum jump fast and efficiently enough,” said Michel Devoret of Yale University, “it is actually a continuous process.” The study, which was led by Zlatko Minev, a graduate student in Devoret’s lab, was published on Monday in Nature [noted above]. Already, colleagues are excited. “This is really a fantastic experiment,” said the physicist William Oliver of the Massachusetts Institute of Technology, who wasn’t involved in the work. “Really amazing.”

But there’s more. With their high-speed monitoring system, the researchers could spot when a quantum jump was about to appear, “catch” it halfway through, and reverse it, sending the system back to the state in which it started. In this way, what seemed to the quantum pioneers to be unavoidable randomness in the physical world is now shown to be amenable to control. We can take charge of the quantum.

All Too Random

The abruptness of quantum jumps was a central pillar of the way quantum theory was formulated by Niels Bohr, Werner Heisenberg and their colleagues in the mid-1920s, in a picture now commonly called the Copenhagen interpretation. Bohr had argued earlier that the energy states of electrons in atoms are “quantized”: Only certain energies are available to them, while all those in between are forbidden. He proposed that electrons change their energy by absorbing or emitting quantum particles of light — photons — that have energies matching the gap between permitted electron states. This explained why atoms and molecules absorb and emit very characteristic wavelengths of light — why many copper salts are blue, say, and sodium lamps yellow.

Bohr and Heisenberg began to develop a mathematical theory of these quantum phenomena in the 1920s. Heisenberg’s quantum mechanics enumerated all the allowed quantum states, and implicitly assumed that jumps between them are instant — discontinuous, as mathematicians would say. “The notion of instantaneous quantum jumps … became a foundational notion in the Copenhagen interpretation,” historian of science Mara Beller has written.

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U Chicago Press Books

Another of the architects of quantum mechanics, the Austrian physicist Erwin Schrödinger, hated that idea. He devised what seemed at first to be an alternative to Heisenberg’s math of discrete quantum states and instant jumps between them. Schrödinger’s theory represented quantum particles in terms of wavelike entities called wave functions, which changed only smoothly and continuously over time, like gentle undulations on the open sea. Things in the real world don’t switch suddenly, in zero time, Schrödinger thought — discontinuous “quantum jumps” were just a figment of the mind. In a 1952 paper called “Are there quantum jumps?,” [BJPS] Schrödinger answered with a firm “no,” his irritation all too evident in the way he called them “quantum jerks.”

The argument wasn’t just about Schrödinger’s discomfort with sudden change. The problem with a quantum jump was also that it was said to just happen at a random moment — with nothing to say why that particular moment. It was thus an effect without a cause, an instance of apparent randomness inserted into the heart of nature. Schrödinger and his close friend Albert Einstein could not accept that chance and unpredictability reigned at the most fundamental level of reality. According to the German physicist Max Born, the whole controversy was therefore “not so much an internal matter of physics, as one of its relation to philosophy and human knowledge in general.” In other words, there’s a lot riding on the reality (or not) of quantum jumps.

Seeing Without Looking

To probe further, we need to see quantum jumps one at a time. In 1986, three teams of researchers reported [Physical Review Letters] them [Physical Review Letters] happening [Physical Review Letters] in individual atoms suspended in space by electromagnetic fields. The atoms flipped between a “bright” state, where they could emit a photon of light, and a “dark” state that did not emit at random moments, remaining in one state or the other for periods of between a few tenths of a second and a few seconds before jumping again. Since then, such jumps have been seen in various systems, ranging from photons switching between quantum states to atoms in solid materials jumping between quantized magnetic states. In 2007 a team in France reported [Nature] jumps that correspond to what they called “the birth, life and death of individual photons.”

In these experiments the jumps indeed looked abrupt and random — there was no telling, as the quantum system was monitored, when they would happen, nor any detailed picture of what a jump looked like. The Yale team’s setup, by contrast, allowed them to anticipate when a jump was coming, then zoom in close to examine it. The key to the experiment is the ability to collect just about all of the available information about it, so that none leaks away into the environment before it can be measured. Only then can they follow single jumps in such detail.

The quantum systems the researchers used are much larger than atoms, consisting of wires made from a superconducting material — sometimes called “artificial atoms” because they have discrete quantum energy states analogous to the electron states in real atoms. Jumps between the energy states can be induced by absorbing or emitting a photon, just as they are for electrons in atoms.

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Michel Devoret (left) and Zlatko Minev in front of the cryostat holding their experiment. Yale Quantum Institute

Devoret and colleagues wanted to watch a single artificial atom jump between its lowest-energy (ground) state and an energetically excited state. But they couldn’t monitor that transition directly, because making a measurement on a quantum system destroys the coherence of the wave function — its smooth wavelike behavior — on which quantum behavior depends. To watch the quantum jump, the researchers had to retain this coherence. Otherwise they’d “collapse” the wave function, which would place the artificial atom in one state or the other. This is the problem famously exemplified by Schrödinger’s cat, which is allegedly placed in a coherent quantum “superposition” of live and dead states but becomes only one or the other when observed.

To get around this problem, Devoret and colleagues employ a clever trick involving a second excited state. The system can reach this second state from the ground state by absorbing a photon of a different energy. The researchers probe the system in a way that only ever tells them whether the system is in this second “bright” state, so named because it’s the one that can be seen. The state to and from which the researchers are actually looking for quantum jumps is, meanwhile, the “dark” state — because it remains hidden from direct view.

The researchers placed the superconducting circuit in an optical cavity (a chamber in which photons of the right wavelength can bounce around) so that, if the system is in the bright state, the way that light scatters in the cavity changes. Every time the bright state decays by emission of a photon, the detector gives off a signal akin to a Geiger counter’s “click.”

The key here, said Oliver, is that the measurement provides information about the state of the system without interrogating that state directly. In effect, it asks whether the system is in, or is not in, the ground and dark states collectively. That ambiguity is crucial for maintaining quantum coherence during a jump between these two states. In this respect, said Oliver, the scheme that the Yale team has used is closely related to those employed for error correction in quantum computers. There, too, it’s necessary to get information about quantum bits without destroying the coherence on which the quantum computation relies. Again, this is done by not looking directly at the quantum bit in question but probing an auxiliary state coupled to it.

The strategy reveals that quantum measurement is not about the physical perturbation induced by the probe but about what you know (and what you leave unknown) as a result. “Absence of an event can bring as much information as its presence,” said Devoret. He compares it to the Sherlock Holmes story in which the detective infers a vital clue from the “curious incident” in which a dog did not do anything in the night. Borrowing from a different (but often confused) dog-related Holmes story, Devoret calls it “Baskerville’s Hound meets Schrödinger’s Cat.”

To Catch a Jump

The Yale team saw a series of clicks from the detector, each signifying a decay of the bright state, arriving typically every few microseconds. This stream of clicks was interrupted approximately every few hundred microseconds, apparently at random, by a hiatus in which there were no clicks. Then after a period of typically 100 microseconds or so, the clicks resumed. During that silent time, the system had presumably undergone a transition to the dark state, since that’s the only thing that can prevent flipping back and forth between the ground and bright states.

So here in these switches from “click” to “no-click” states are the individual quantum jumps — just like those seen in the earlier experiments on trapped atoms and the like. However, in this case Devoret and colleagues could see something new.

Before each jump to the dark state, there would typically be a short spell where the clicks seemed suspended: a pause that acted as a harbinger of the impending jump. “As soon as the length of a no-click period significantly exceeds the typical time between two clicks, you have a pretty good warning that the jump is about to occur,” said Devoret.

That warning allowed the researchers to study the jump in greater detail. When they saw this brief pause, they switched off the input of photons driving the transitions. Surprisingly, the transition to the dark state still happened even without photons driving it — it is as if, by the time the brief pause sets in, the fate is already fixed. So although the jump itself comes at a random time, there is also something deterministic in its approach.

With the photons turned off, the researchers zoomed in on the jump with fine-grained time resolution to see it unfold. Does it happen instantaneously — the sudden quantum jump of Bohr and Heisenberg? Or does it happen smoothly, as Schrödinger insisted it must? And if so, how?

The team found that jumps are in fact gradual. That’s because, even though a direct observation could reveal the system only as being in one state or another, during a quantum jump the system is in a superposition, or mixture, of these two end states. As the jump progresses, a direct measurement would be increasingly likely to yield the final rather than the initial state. It’s a bit like the way our decisions may evolve over time. You can only either stay at a party or leave it — it’s a binary choice — but as the evening wears on and you get tired, the question “Are you staying or leaving?” becomes increasingly likely to get the answer “I’m leaving.”

The techniques developed by the Yale team reveal the changing mindset of a system during a quantum jump. Using a method called tomographic reconstruction, the researchers could figure out the relative weightings of the dark and ground states in the superposition. They saw these weights change gradually over a period of a few microseconds. That’s pretty fast, but it’s certainly not instantaneous.

What’s more, this electronic system is so fast that the researchers could “catch” the switch between the two states as it is happening, then reverse it by sending a pulse of photons into the cavity to boost the system back to the dark state. They can persuade the system to change its mind and stay at the party after all.

Flash of Insight

The experiment shows that quantum jumps “are indeed not instantaneous if we look closely enough,” said Oliver, “but are coherent processes”: real physical events that unfold over time.

The gradualness of the “jump” is just what is predicted by a form of quantum theory called quantum trajectories theory, which can describe individual events like this. “It is reassuring that the theory matches perfectly with what is seen” said David DiVincenzo, an expert in quantum information at Aachen University in Germany, “but it’s a subtle theory, and we are far from having gotten our heads completely around it.”

The possibility of predicting quantum jumps just before they occur, said Devoret, makes them somewhat like volcanic eruptions. Each eruption happens unpredictably, but some big ones can be anticipated by watching for the atypically quiet period that precedes them. “To the best of our knowledge, this precursory signal [to a quantum jump] has not been proposed or measured before,” he said.

Devoret said that an ability to spot precursors to quantum jumps might find applications in quantum sensing technologies. For example, “in atomic clock measurements, one wants to synchronize the clock to the transition frequency of an atom, which serves as a reference,” he said. But if you can detect right at the start if the transition is about to happen, rather than having to wait for it to be completed, the synchronization can be faster and therefore more precise in the long run.

DiVincenzo thinks that the work might also find applications in error correction for quantum computing, although he sees that as “quite far down the line.” To achieve the level of control needed for dealing with such errors, though, will require this kind of exhaustive harvesting of measurement data — rather like the data-intensive situation in particle physics, said DiVincenzo.

The real value of the result is not, though, in any practical benefits; it’s a matter of what we learn about the workings of the quantum world. Yes, it is shot through with randomness — but no, it is not punctuated by instantaneous jerks. Schrödinger, aptly enough, was both right and wrong at the same time.

See the full article here .


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Formerly known as Simons Science News, Quanta Magazine is an editorially independent online publication launched by the Simons Foundation to enhance public understanding of science. Why Quanta? Albert Einstein called photons “quanta of light.” Our goal is to “illuminate science.” At Quanta Magazine, scientific accuracy is every bit as important as telling a good story. All of our articles are meticulously researched, reported, edited, copy-edited and fact-checked.

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From Yale University: Women in STEM: “Math — not computer science — was Grace Hopper’s first language”

Yale University bloc

From Yale University

March 26, 2019

Kendall Teare
kendall.teare@yale.edu
203-836-4226

Commodore Grace M. Hopper, USN

Hopper near Cruft Lab, Harvard University ca. 1945–1947 where she worked on the Mark I computer. Photo courtesy of Grace Murray Hopper Collection, National Museum of American History, Smithsonian Institution

For her pioneering work in computer science, Grace Murray Hopper ’30 M.A., ’34 Ph.D. has been dubbed the “queen of code” by her biographers. Yet, beneath that crown was the brain of a mathematician, according to an article in Notices of the American Mathematical Society (PDF) by Gibbs Assistant Professor of Mathematics Asher Auel that makes the details of Hopper’s doctoral training in mathematics public for the first time.

“In some sense, you could think of mathematics as the liberal arts of the sciences,” said Auel. “It is the language that you will be using in all scientific disciplines. It’s a way of knowing, a way of thinking, a way of understanding truth.” Studying math is studying problem solving — the necessary skill for anyone who wants to be able to approach a future problem that doesn’t exist now, he explained — for example, building the first computer.

“Sometimes people think Hopper was ‘only’ a foundational computer scientist or ‘only’ a naval officer,’ but that was just the beginning,” said Julia Adams, head of Grace Hopper College and professor of sociology. “It’s important that people realize that she had four or five illustrious careers, each of which would have done her great honor: mathematician, foundational computer scientist, naval officer, teacher, and public intellectual.”

Adams has invited Auel to discuss his paper on Hopper’s lesser-known “mathematical origins” at a college tea in the Hopper Head of College House (189 Elm St.) on Wed., April 3 at 4 p.m. This event is free and open to the Yale community.

In his paper, after listing the many instances in which Hopper self-described as a mathematician, Auel asserts that it was Hopper’s initial training in mathematics that gave her the tools to help build the discipline of computer science with which she’s most often associated. As Auel describes, television host David Letterman once asked Hopper about her work on the Mark I computer: “Now, how did you know so much about computers then?” To which Hopper replied, “I didn’t. It was the first one.”

Letterman’s assumption that Hopper would have needed a background in computer science in order to have succeeded in her later career has persisted in even the most authoritative biography on Hopper, which is being used as the basis for a forthcoming Google-produced biopic, said Auel. That biography and others have claimed that for her Yale doctoral degree Hopper studied everything from mathematical physics — a program Yale did not offer in the 1930s — to computer science — a program that no school offered in the 1930s.

Also, Auel says, Hopper didn’t just study “math” at Yale, she studied “pure algebra,” with a focus on algebraic number theory and geometry, highly theoretical topics with no direct practical applications at the time but which require an advanced ability to think in symbols. Auel believes that it was this ability to conceptualize abstract numerical and geometrical ideas that helped enable Hopper to invent a new language, that of computer code, which would require a deep and rigorous understanding of existing mathematical languages.

In fall 2015, Auel was teaching Math 350, Yale’s foundational abstract algebra course, for the first time. Before the term began, he went to the Mathematics Library at 12 Hillhouse Ave. to gather background on the history of abstract algebraists at Yale for his opening lecture. Paul Lukasiewicz, the now-retired, 40-year-veteran math librarian, put him on Hopper’s trail. Until then, Auel too had only associated Hopper with computer science.

On the first day of class, when Auel told his standing-room-only lecture that Hopper had taken a version of that very same course likely in the very same classroom while she was a graduate student in math at Yale, he was met with audible delight and excitement from students.

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Hopper’s Yale graduate school transcript. (Image courtesy of Graduate School of Arts and Sciences, Yale University, Student Records [RU 262], Manuscripts and Archives, Yale University Library. Reproduction in consultation with family representatives Roger and Deborah Murray)

“I think that reclaiming Grace Hopper’s mathematical legacy is a great step for the math community,” said Catherine Lee ’20, a junior in Grace Hopper College who is majoring in math and is the former co-president of the Yale Undergraduate Math Society. “Studying math is isolating at times because it’s a discipline that isn’t well understood or widely appreciated in popular culture, and having strong role models can be important.”

“The Grace Hopper Conference [an annual conference for women in computer science] has been tremendously inspirational to women in computer science,” added Lee. “I hope that recognizing Hopper’s work as a mathematician will prove similarly empowering, especially at Yale, since Hopper is a very prominent figure here and there’s a serious demand right now for increased representation of female mathematicians on campus.” Lee is also a member of Dimensions, “the first organization at Yale that aims to inspire, celebrate, and empower women and gendered minorities in mathematics.”

Even within the Yale math department, Auel found that few colleagues knew about Hopper’s Yale math legacy. This is likely because, unlike the theses of her male peers, Hopper’s was never published. She presented the paper at a meeting of the American Mathematical Society, which made the March 1934 Bulletin of the American Mathematical Society as a one-paragraph-long abstract in a long list. Hopper’s thesis is now available in its entirety online at the Yale math department website.

In 1934, Hopper completed her doctoral degree with a dissertation on “new types of irreducibility criteria,” under the supervision of then Sterling Professor Øystein Ore, who is a noted figure in the history of algebra at Yale. She studied figures called Newton polygons, which are produced in an X-Y coordinate plane starting from a polynomial. These polygons are helpful in determining whether or not a polynomial can be reduced to a product of smaller degree polynomials.

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Hopper hand drew the geometric illustrations for her thesis. This is her depiction of the “Minkowski sum” of the Newton polygons of two polynomials. (Image courtesy of Manuscripts and Archives, Yale University Library. Reproduction of details from Grace Murray Hopper’s Ph.D. dissertation [19] in consultation with family representatives Roger and Deborah Murray)

“While this idea of connecting Newton polygons with the irreducibility of polynomials had been floating around for about 20 years before Hopper came to it in her dissertation, the way she wrote about it was so modern,” said Auel, who will be leaving Yale at the end of spring 2019 to join the faculty at Dartmouth College.

The principle she identified is now an accepted theorem in abstract algebra, and the way she explained it is similar to how mathematicians understand it today. “The understanding she had was beyond her time,” said Auel. “Only 20 to 30 years after Hopper’s thesis did I see re-enunciations of the same philosophy in mathematics literature.”

Prior to Auel, the only scholars who’d examined the particulars of Hopper’s mathematical training were Judy Green ’66 M.A. and Jeanne LaDuke, two mathematicians who co-authored a comprehensive math history book, “Pioneering Women in Mathematics: The Pre-1940 Ph.D.’s.”, and supplementary material on the 228 mathematicians profiled. According to Green and LaDuke’s count, Hopper was actually the twelfth woman to receive a math Ph.D. from Yale. The first was Charlotte Barnum in 1895 for a dissertation on “functions having lines or surfaces of discontinuity.”

In 2019-2020, Yale will celebrate the achievements of its trailblazing female scholars like Barnum and Hopper while marking the 150th anniversary of women in Yale’s graduate and professional programs and the 50th anniversary of women in Yale College. For more information about this upcoming dual anniversary, visit the Celebrating Women at Yale website.

Grace Hopper, One of the first programmers of the Harvard Mark I computer.

NERSC Hopper Cray XE6 supercomputer

See the full article here .

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Yale University Campus

Yale University comprises three major academic components: Yale College (the undergraduate program), the Graduate School of Arts and Sciences, and the professional schools. In addition, Yale encompasses a wide array of centers and programs, libraries, museums, and administrative support offices. Approximately 11,250 students attend Yale.

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From Yale University: “PROSPECTing for antineutrinos”

Yale University bloc

From Yale University

ORNL

May 18, 2018
Jim Shelton
james.shelton@yale.edu
203-361-8332

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Assembly of the PROSPECT neutrino detector. (Image credit: PROSPECT collaboration/Mara Lavitt)

The Precision Reactor Oscillation and Spectrum Experiment (PROSPECT) has completed the installation of a novel antineutrino detector that will probe the possible existence of a new form of matter.

PROSPECT, located at the High Flux Isotope Reactor (HFIR) at the Department of Energy’s Oak Ridge National Laboratory (ORNL), has begun taking data to study electron antineutrinos that are emitted from nuclear decays in the reactor to search for so-called sterile neutrinos and to learn about the underlying nuclear reactions that power fission reactors.

Antineutrinos are elusive, elementary particles produced in nuclear beta decay. The antineutrino is an antimatter particle, the counterpart to the neutrino.

“Neutrinos are among the most abundant particles in the universe,” said Yale University physicist Karsten Heeger, principal investigator and co-spokesperson for PROSPECT. “The discovery of neutrino oscillation has opened a window to physics beyond the Standard Model of Physics. The study of antineutrinos with PROSPECT allows us to search for a previously unobserved particle, the so-called sterile neutrino, while probing the nuclear processes inside a reactor.”

Over the past few years several neutrino experiments at nuclear reactors have detected fewer antineutrinos than scientists had predicted, and the energy of the neutrinos did not match expectations. This, in combination with earlier anomalous results, led to the hypothesis that a fraction of electron antineutrinos may transform into sterile neutrinos that would have remained undetected in previous experiments.

This hypothesized transformation would take place through a quantum mechanical process called neutrino oscillation. The first observation of neutrino oscillation amongst known types of neutrinos from the sun and the atmosphere led to the 2015 Nobel Prize in physics.

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(Image credit: PROSPECT collaboration/Mara Lavitt)

The installation of PROSPECT follows four years of intensive research and development by a collaboration of more than 60 participants from 10 universities and four national laboratories.

“The development of PROSPECT is based on years of research in the detection of reactor antineutrinos with surface-based detectors, an extremely challenging task because of high backgrounds,” said PROSPECT co-spokesperson Pieter Mumm, a scientist at the National Institute of Standards and Technology (NIST).

The experiment uses a novel antineutrino detector system based on a segmented liquid scintillator detector technology. The combination of segmentation and a unique, lithium-doped liquid scintillator formulation allows PROSPECT to identify particle types and interaction points. These design features, along with extensive, tailored shielding, will enable PROSPECT to make a precise measurement of neutrinos in the high-background environment of a nuclear reactor.

PROSPECT’s detector technology also may have applications in the monitoring of nuclear reactors for non-proliferation purposes and the measurement of neutrons from nuclear processes.

“The successful operation of PROSPECT will allow us to gain insight into one of the fundamental puzzles in neutrino physics and develop a better understanding of reactor fuel, while also providing a new tool for nuclear safeguards,” said co-spokesperson Nathaniel Bowden, a scientist at Lawrence Livermore National Laboratory and an expert in nuclear non-proliferation technology.

After two years of construction and final assembly at the Yale Wright Laboratory, the PROSPECT detector was transported to HFIR in early 2018.

“The development and construction of PROSPECT has been a significant team effort, making use of the complementary expertise at U.S. national laboratories and universities,” said Alfredo Galindo-Uribarri, leader of the Neutrino and Advanced Detectors group in ORNL’s Physics Division.

PROSPECT is the latest in a series of fundamental science experiments located at HFIR. “We are excited to work with PROSPECT scientists to support their research,” said Chris Bryan, who manages experiments at HFIR for ORNL’s Research Reactors Division.

The experiment is supported by the U.S. Department of Energy Office of Science, the Heising-Simons Foundation, and the National Science Foundation. Additional support comes from Yale University, the Illinois Institute of Technology, and the Lawrence Livermore National Laboratory LDRD program. The collaboration also benefits from the support and hospitality of the High Flux Isotope Reactor, a DOE Office of Science User Facility, and Oak Ridge National Laboratory, managed by UT-Battelle for the U.S. Department of Energy.

See the full article here .

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Yale University Campus

Yale University comprises three major academic components: Yale College (the undergraduate program), the Graduate School of Arts and Sciences, and the professional schools. In addition, Yale encompasses a wide array of centers and programs, libraries, museums, and administrative support offices. Approximately 11,250 students attend Yale.

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From Yale: Women in STEM: “Black holes, gravitational waves take Yale prof to NASA’s LISA mission” Priyamvada Natarajan

Yale University bloc

Yale University

January 9, 2018
Jim Shelton

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Priyamvada Natarajan

NASA has named professor of astronomy and physics Priyamvada Natarajan to its team of U.S. scientists lending expertise on gravitational waves and astrophysics for the upcoming LISA mission.

LISA — which stands for Laser Interferometer Space Antenna — is a space-based, gravitational wave observatory that will be composed of three spacecraft separated by millions of miles. The mission, scheduled for the early 2030s, is a collaboration between NASA, the European Space Agency, and the LISA consortium.

ESA/NASA eLISA space based the future of gravitational wave research

Natarajan is a member of the NASA LISA Study Team.

“The detection of gravitational waves in 2015 by the LIGO (Laser Interferometer Gravitational-Wave Observatory) collaboration is one of the major scientific breakthroughs of this century,” Natarajan said.


VIRGO Gravitational Wave interferometer, near Pisa, Italy

Caltech/MIT Advanced aLigo Hanford, WA, USA installation


Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

ESA/eLISA the future of gravitational wave research

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Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

“The tremors they identified in space-time, produced by the collision of two stellar-mass black holes, was extremely challenging to detect. The more massive cousins of these black holes are supermassive black holes that reside in the centers of most, if not all, galaxies.”

Supermassive black holes also are likely to have been built up via mergers, Natarajan explained. “The cosmic earthquakes produced during these collisions cannot be detected from the Earth and require a LIGO-like interferometer in space as these events will be detectable at much lower frequencies,” she said. “The LISA mission plans to detect these gravitational waves from space-based detectors. The mission will test our fundamental understanding of how supermassive black holes form and grow.”

Natarajan’s research focuses on understanding the formation of the first black holes and the accumulation of mass in the most massive black holes in the universe.

“We currently believe that black holes grow both via direct consumption of gas and stars in their vicinity, as well as via mergers with other black holes,” Natarajan said. “The detection of gravitational waves from colliding supermassive black holes by LISA would validate and calibrate the relative importance of mergers versus accretion.”

Natarajan’s research into black holes also figures prominently in the Jan. 10 episode of the PBS science documentary series, “NOVA – Black Hole Apocalypse.”

“My research group at Yale is extremely active and we are working at the leading edge of these questions combining theoretical models, numerical simulations, and the most up-to-date multi-wavelength observations,” Natarajan said.

See the full article here .

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Yale University comprises three major academic components: Yale College (the undergraduate program), the Graduate School of Arts and Sciences, and the professional schools. In addition, Yale encompasses a wide array of centers and programs, libraries, museums, and administrative support offices. Approximately 11,250 students attend Yale.

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From Yale: “Genetic risk of autism spectrum disorder linked to evolutionary brain benefit”

Yale University bloc

Yale University

February 27, 2017 [Brought back for interest]
Bill Hathaway

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(© stock.adobe.com) Not a young Dr. Sheldon Cooper?

Genetic variants linked to autism spectrum disorders (ASD) may have been positively selected during human evolution because they also contribute to enhanced cognition, a new Yale study suggests.

A study based on a genome-wide association study of ASD conducted by the Psychiatric Genomics Consortium and information regarding evolutionary gene selection showed that inherited variants linked to ASD were found under positive selection in larger numbers than would have been expected by chance.

The final version of the paper was published Feb. 27 in the journal PLOS Genetics.

Variants that have a large negative impact on reproductive success are generally eliminated from the population quickly. However, common variants that occur with high frequency but small effect can cumulatively have big impacts on complex inherited traits — both positive and negative. If variants provide a better chance of survival, they are positively selected, or tend to stay in the genome through generations.

“In this case, we found a strong positive signal that, along with autism spectrum disorder, these variants are also associated with intellectual achievement,” said Renato Polimanti, associate research scientist at Yale School of Medicine and VA Connecticut Health Center in West Haven, and first author of the paper.

For instance, many of the positively selected variants associated with ASD identified by the researchers were enriched for molecular functions related to creation of new neurons.

“It might be difficult to imagine why the large number of gene variants that together give rise to traits like ASD are retained in human populations — why aren’t they just eliminated by evolution?” said Joel Gelernter, the Foundations Fund Professor of Psychiatry, professor of genetics and of neuroscience, and co-author. “The idea is that during evolution these variants that have positive effects on cognitive function were selected, but at a cost — in this case an increased risk of autism spectrum disorders.”

The work was funded by National Institutes of Health grants and a NARSAD Young Investigator Award from the Brain & Behavior Research Foundation.

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Yale University Campus

Yale University comprises three major academic components: Yale College (the undergraduate program), the Graduate School of Arts and Sciences, and the professional schools. In addition, Yale encompasses a wide array of centers and programs, libraries, museums, and administrative support offices. Approximately 11,250 students attend Yale.

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From NYT: “Yale Professors Race Google and IBM to the First Quantum Computer”

New York Times

The New York Times

NOV. 13, 2017
CADE METZ

1
Prof. Robert Schoelkopf inside a lab at Yale University. Quantum Circuits, the start-up he has created with two of his fellow professors, is located just down the road. Credit Roger Kisby for The New York Times

Robert Schoelkopf is at the forefront of a worldwide effort to build the world’s first quantum computer. Such a machine, if it can be built, would use the seemingly magical principles of quantum mechanics to solve problems today’s computers never could.

Three giants of the tech world — Google, IBM, and Intel — are using a method pioneered by Mr. Schoelkopf, a Yale University professor, and a handful of other physicists as they race to build a machine that could significantly accelerate everything from drug discovery to artificial intelligence. So does a Silicon Valley start-up called Rigetti Computing. And though it has remained under the radar until now, those four quantum projects have another notable competitor: Robert Schoelkopf.

After their research helped fuel the work of so many others, Mr. Schoelkopf and two other Yale professors have started their own quantum computing company, Quantum Circuits.

Based just down the road from Yale in New Haven, Conn., and backed by $18 million in funding from the venture capital firm Sequoia Capital and others, the start-up is another sign that quantum computing — for decades a distant dream of the world’s computer scientists — is edging closer to reality.

“In the last few years, it has become apparent to us and others around the world that we know enough about this that we can build a working system,” Mr. Schoelkopf said. “This is a technology that we can begin to commercialize.”

Quantum computing systems are difficult to understand because they do not behave like the everyday world we live in. But this counterintuitive behavior is what allows them to perform calculations at rate that would not be possible on a typical computer.

Today’s computers store information as “bits,” with each transistor holding either a 1 or a 0. But thanks to something called the superposition principle — behavior exhibited by subatomic particles like electrons and photons, the fundamental particles of light — a quantum bit, or “qubit,” can store a 1 and a 0 at the same time. This means two qubits can hold four values at once. As you expand the number of qubits, the machine becomes exponentially more powerful.

Todd Holmdahl, who oversees the quantum project at Microsoft, said he envisioned a quantum computer as something that could instantly find its way through a maze. “A typical computer will try one path and get blocked and then try another and another and another,” he said. “A quantum computer can try all paths at the same time.”

The trouble is that storing information in a quantum system for more than a short amount of time is very difficult, and this short “coherence time” leads to errors in calculations. But over the past two decades, Mr. Schoelkopf and other physicists have worked to solve this problem using what are called superconducting circuits. They have built qubits from materials that exhibit quantum properties when cooled to extremely low temperatures.

With this technique, they have shown that, every three years or so, they can improve coherence times by a factor of 10. This is known as Schoelkopf’s Law, a playful ode to Moore’s Law, the rule that says the number of transistors on computer chips will double every two years.

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Professor Schoelkopf, left, and Prof. Michel Devoret working on a device that can reach extremely low temperatures to allow a quantum computing device to function. Credit Roger Kisby for The New York Times

“Schoelkopf’s Law started as a joke, but now we use it in many of our research papers,” said Isaac Chuang, a professor at the Massachusetts Institute of Technology. “No one expected this would be possible, but the improvement has been exponential.”

These superconducting circuits have become the primary area of quantum computing research across the industry. One of Mr. Schoelkopf’s former students now leads the quantum computing program at IBM. The founder of Rigetti Computing studied with Michel Devoret, one of the other Yale professors behind Quantum Circuits.

In recent months, after grabbing a team of top researchers from the University of California, Santa Barbara, Google indicated it is on the verge of using this method to build a machine that can achieve “quantum supremacy” — when a quantum machine performs a task that would be impossible on your laptop or any other machine that obeys the laws of classical physics.

There are other areas of research that show promise. Microsoft, for example, is betting on particles known as anyons. But superconducting circuits appear likely to be the first systems that will bear real fruit.

The belief is that quantum machines will eventually analyze the interactions between physical molecules with a precision that is not possible today, something that could radically accelerate the development of new medications. Google and others also believe that these systems can significantly accelerate machine learning, the field of teaching computers to learn tasks on their own by analyzing data or experiments with certain behavior.

A quantum computer could also be able to break the encryption algorithms that guard the world’s most sensitive corporate and government data. With so much at stake, it is no surprise that so many companies are betting on this technology, including start-ups like Quantum Circuits.

The deck is stacked against the smaller players, because the big-name companies have so much more money to throw at the problem. But start-ups have their own advantages, even in such a complex and expensive area of research.

“Small teams of exceptional people can do exceptional things,” said Bill Coughran, who helped oversee the creation of Google’s vast internet infrastructure and is now investing in Mr. Schoelkopf’s company as a partner at Sequoia. “I have yet to see large teams inside big companies doing anything tremendously innovative.”

Though Quantum Circuits is using the same quantum method as its bigger competitors, Mr. Schoelkopf argued that his company has an edge because it is tackling the problem differently. Rather than building one large quantum machine, it is constructing a series of tiny machines that can be networked together. He said this will make it easier to correct errors in quantum calculations — one of the main difficulties in building one of these complex machines.

But each of the big companies insist that they hold an advantage — and each is loudly trumpeting its progress, even if a working machine is still years away.

Mr. Coughran said that he and Sequoia envision Quantum Circuits evolving into a company that can deliver quantum computing to any business or researcher that needs it. Another investor, Canaan’s Brendan Dickinson, said that if a company like this develops a viable quantum machine, it will become a prime acquisition target.

“The promise of a large quantum computer is incredibly powerful,” Mr. Dickinson said. “It will solve problems we can’t even imagine right now.”

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From Yale: “Cellular clean-up can also sweep away forms of cancer”

Yale University bloc

Yale University

November 9, 2017
Bill Hathaway

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Cells treated (right) or untreated (left) with a PROTAC that degrades the target protein (green). No image credit.

Two new research papers reinforce the benefits of a novel therapy that hijacks the cell’s own protein degradation machinery to destroy cancer cells, Yale researchers report Nov. 9 in the journal Cell Chemical Biology.

The new approach to drug discovery, called Proteolysis Targeting Chimeras or PROTACs, was developed in the laboratory of Craig Crews, the Lewis B. Cullman Professor of Molecular, Cellular, and Developmental Biology, professor of chemistry and pharmacology, as well as executive director of the Yale Center for Molecular Discovery.

The system engages the cell’s own protein degradation machinery to destroy targeted proteins by tagging them for removal. Most drugs are based on the ability of small molecules to bind to and block the function of disease-causing proteins, but some proteins are resistant to such intervention.

“This system will help us change the current small-molecule drug paradigm that fails to target 75% of rogue proteins,” said Crews, scientific founder of Arvinas LLC, the New Haven biotechnology company developing the concept.

The first paper, [Cell Chemical Biology] shows for the first time that PROTAC system can target mutant RTK proteins, which have been linked to several forms of cancer. The second paper [Cell Chemical Biology] proves that the PROTAC system can target rogue proteins with greater specificity than traditional approaches.

Yale’s George M. Burslem and Blake E. Smith are first authors of the first paper. Smith and Yale’s Daniel P. Bondeson are co-first authors of the second paper.

The two papers were primarily funded by the National Institutes of Health. Crews is a shareholder of Arvinas, which also provided researchers to the projects.

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Yale University Campus

Yale University comprises three major academic components: Yale College (the undergraduate program), the Graduate School of Arts and Sciences, and the professional schools. In addition, Yale encompasses a wide array of centers and programs, libraries, museums, and administrative support offices. Approximately 11,250 students attend Yale.

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