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  • richardmitnick 9:20 am on June 18, 2021 Permalink | Reply
    Tags: "Physicists Nearly Reach Elusive Quantum Ground State on The Largest 'Object' Yet", Achieving the quantum ground state of a cloud of atoms isn't easy. You need to cool the atom by applying just the right amount of force to stop its vibrations., , , Classical physics, , , , , , , , The work represents a new way to probe the quantum realm.   

    From Massachusetts Institute of Technology (US) via Science Alert (AU) : “Physicists Nearly Reach Elusive Quantum Ground State on The Largest ‘Object’ Yet” 

    MIT News

    From Massachusetts Institute of Technology (US)

    via

    http://www.sciencealert.com/”> Science Alert (AU)

    17 JUNE 2021
    MICHELLE STARR

    1
    One of LIGO’s mirrors. Credit: Caltech/ MIT Advanced aLIGO (US).

    Very rarely is anything completely still. All normal matter in the Universe is made of humming particles, minding their own business and vibrating at their own frequencies.

    If we can get them to slow down as much as possible, the material enters what is known as the motional ground state. In this state, physicists can perform tests of quantum mechanics and quantum gravity, probing the boundary with classical physics to search for a way to unify the two.

    Previously, this has been performed in the nanoscale; but now, for the first time, it’s been done on a massive ‘object’ – the collective motions of the four mirrors of the LIGO gravitational wave interferometer, known as an optomechanical oscillator, with an effective mass of 10 kilograms (22 pounds).

    Caltech /MIT Advanced aLigo .

    The work represents a new way to probe the quantum realm.

    “Nobody has ever observed how gravity acts on massive quantum states,” said mechanical engineer Vivishek Sudhir of MIT.

    “We’ve demonstrated how to prepare kilogram-scale objects in quantum states. This finally opens the door to an experimental study of how gravity might affect large quantum objects, something hitherto only dreamed of.”

    Achieving the quantum ground state of a cloud of atoms isn’t easy. You need to cool the atom by applying just the right amount of force to stop its vibrations. If you don’t cool it enough, it merely slows; so you need to know the exact energy level and direction of the atom’s vibrations in order to apply the appropriate force to stop it.

    This is called ‘feedback cooling’, and on the nanoscale it’s simpler to do, because it’s easier to isolate the smaller groups of atoms and minimize interference. The larger you go, though, the harder it becomes to handle that interference.

    LIGO is one of the most precise instruments for measuring fine motion. It’s designed to detect tiny ripples in space-time generated by collisions between massive objects up to billions of light-years away.

    It consists of an L-shaped vacuum chamber, with laser lights beamed along its two 4-kilometer (2.5-mile) tunnels, and sent to a beam splitter to four mirrors, one at each end of each tunnel. When space-time ripples, the mirrors distort the light, producing an interference pattern that scientists can decode to determine the cause. And it’s so sensitive that it can detect a change just one ten-thousandth the width of a proton, or 10-19 meters.

    Each of LIGO’s four 40-kilogram mirrors is suspended, and it’s their collective motion that makes up the oscillator. The balance of the mirrors effectively reduces 160 kilograms of total weight to a single object of just 10 kilograms.

    “LIGO is designed to measure the joint motion of the four 40-kilogram mirrors,” Sudhir said. “It turns out you can map the joint motion of these masses mathematically, and think of them as the motion of a single 10-kilogram object.”

    By precisely measuring the motion of this oscillator, the team hoped to work out exactly the rate of feedback cooling required to induce the motional ground state… and then, obviously, apply it.

    Unfortunately the very act of measuring throws a degree of randomness into the equation, making it difficult to predict the kinds of nudges needed to sap the energy out of the mirror’s atoms.

    To correct for this, the team cleverly studied each photon to estimate the activity of previous collisions, continuously building a more accurate map of how to apply the correct forces and achieve cooling.

    Then, they applied the calculated force using electromagnets attached to the backs of the mirrors.

    It worked. The oscillator stopped moving, almost completely. Its remaining energy was equivalent to a temperature of 77 nanokelvin (-273.15 degrees Celsius, or -459.67 degrees Fahrenheit).

    Its motional ground state, 10 nanokelvin, is extremely close, especially considering the room temperature starting point. And 77 nanokelvin is also very close to the temperatures used in motional ground state studies on the nanoscale.

    Moreover, it opens the door to some exciting possibilities. Macro-scale demonstrations and measurements of quantum phenomena – and maybe even applications for the same.

    But quantum gravity is the big kicker. Kilogram-mass objects are more susceptible to gravity; the team’s work raises hope to use this mass regime to study the quantum realm.

    “Preparing something in the ground state is often the first step to putting it into exciting or exotic quantum states,” said physicist Chris Whittle of MIT and the LIGO collaboration.

    “So this work is exciting because it might let us study some of these other states, on a mass scale that’s never been done before.”

    The research has been published in Science.

    See the full article here .


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    MIT Campus

    Massachusetts Institute of Technology (US) is a private land-grant research university in Cambridge, Massachusetts. The institute has an urban campus that extends more than a mile (1.6 km) alongside the Charles River. The institute also encompasses a number of major off-campus facilities such as the MIT Lincoln Laboratory, the Bates Center, and the Haystack Observatory, as well as affiliated laboratories such as the Broad and Whitehead Institutes.

    Founded in 1861 in response to the increasing industrialization of the United States, Massachusetts Institute of Technology (US) adopted a European polytechnic university model and stressed laboratory instruction in applied science and engineering. It has since played a key role in the development of many aspects of modern science, engineering, mathematics, and technology, and is widely known for its innovation and academic strength. It is frequently regarded as one of the most prestigious universities in the world.

    As of December 2020, 97 Nobel laureates, 26 Turing Award winners, and 8 Fields Medalists have been affiliated with MIT as alumni, faculty members, or researchers. In addition, 58 National Medal of Science recipients, 29 National Medals of Technology and Innovation recipients, 50 MacArthur Fellows, 80 Marshall Scholars, 3 Mitchell Scholars, 22 Schwarzman Scholars, 41 astronauts, and 16 Chief Scientists of the U.S. Air Force have been affiliated with Massachusetts Institute of Technology (US) . The university also has a strong entrepreneurial culture and MIT alumni have founded or co-founded many notable companies. Massachusetts Institute of Technology (US) is a member of the Association of American Universities (AAU).

    Foundation and vision

    In 1859, a proposal was submitted to the Massachusetts General Court to use newly filled lands in Back Bay, Boston for a “Conservatory of Art and Science”, but the proposal failed. A charter for the incorporation of the Massachusetts Institute of Technology, proposed by William Barton Rogers, was signed by John Albion Andrew, the governor of Massachusetts, on April 10, 1861.

    Rogers, a professor from the University of Virginia (US), wanted to establish an institution to address rapid scientific and technological advances. He did not wish to found a professional school, but a combination with elements of both professional and liberal education, proposing that:

    “The true and only practicable object of a polytechnic school is, as I conceive, the teaching, not of the minute details and manipulations of the arts, which can be done only in the workshop, but the inculcation of those scientific principles which form the basis and explanation of them, and along with this, a full and methodical review of all their leading processes and operations in connection with physical laws.”

    The Rogers Plan reflected the German research university model, emphasizing an independent faculty engaged in research, as well as instruction oriented around seminars and laboratories.

    Early developments

    Two days after Massachusetts Institute of Technology (US) was chartered, the first battle of the Civil War broke out. After a long delay through the war years, MIT’s first classes were held in the Mercantile Building in Boston in 1865. The new institute was founded as part of the Morrill Land-Grant Colleges Act to fund institutions “to promote the liberal and practical education of the industrial classes” and was a land-grant school. In 1863 under the same act, the Commonwealth of Massachusetts founded the Massachusetts Agricultural College, which developed as the University of Massachusetts Amherst (US)). In 1866, the proceeds from land sales went toward new buildings in the Back Bay.

    Massachusetts Institute of Technology (US) was informally called “Boston Tech”. The institute adopted the European polytechnic university model and emphasized laboratory instruction from an early date. Despite chronic financial problems, the institute saw growth in the last two decades of the 19th century under President Francis Amasa Walker. Programs in electrical, chemical, marine, and sanitary engineering were introduced, new buildings were built, and the size of the student body increased to more than one thousand.

    The curriculum drifted to a vocational emphasis, with less focus on theoretical science. The fledgling school still suffered from chronic financial shortages which diverted the attention of the MIT leadership. During these “Boston Tech” years, Massachusetts Institute of Technology (US) faculty and alumni rebuffed Harvard University (US) president (and former MIT faculty) Charles W. Eliot’s repeated attempts to merge MIT with Harvard College’s Lawrence Scientific School. There would be at least six attempts to absorb MIT into Harvard. In its cramped Back Bay location, MIT could not afford to expand its overcrowded facilities, driving a desperate search for a new campus and funding. Eventually, the MIT Corporation approved a formal agreement to merge with Harvard, over the vehement objections of MIT faculty, students, and alumni. However, a 1917 decision by the Massachusetts Supreme Judicial Court effectively put an end to the merger scheme.

    In 1916, the Massachusetts Institute of Technology (US) administration and the MIT charter crossed the Charles River on the ceremonial barge Bucentaur built for the occasion, to signify MIT’s move to a spacious new campus largely consisting of filled land on a one-mile-long (1.6 km) tract along the Cambridge side of the Charles River. The neoclassical “New Technology” campus was designed by William W. Bosworth and had been funded largely by anonymous donations from a mysterious “Mr. Smith”, starting in 1912. In January 1920, the donor was revealed to be the industrialist George Eastman of Rochester, New York, who had invented methods of film production and processing, and founded Eastman Kodak. Between 1912 and 1920, Eastman donated $20 million ($236.6 million in 2015 dollars) in cash and Kodak stock to MIT.

    Curricular reforms

    In the 1930s, President Karl Taylor Compton and Vice-President (effectively Provost) Vannevar Bush emphasized the importance of pure sciences like physics and chemistry and reduced the vocational practice required in shops and drafting studios. The Compton reforms “renewed confidence in the ability of the Institute to develop leadership in science as well as in engineering”. Unlike Ivy League schools, Massachusetts Institute of Technology (US) catered more to middle-class families, and depended more on tuition than on endowments or grants for its funding. The school was elected to the Association of American Universities (US)in 1934.

    Still, as late as 1949, the Lewis Committee lamented in its report on the state of education at Massachusetts Institute of Technology (US) that “the Institute is widely conceived as basically a vocational school”, a “partly unjustified” perception the committee sought to change. The report comprehensively reviewed the undergraduate curriculum, recommended offering a broader education, and warned against letting engineering and government-sponsored research detract from the sciences and humanities. The School of Humanities, Arts, and Social Sciences and the MIT Sloan School of Management were formed in 1950 to compete with the powerful Schools of Science and Engineering. Previously marginalized faculties in the areas of economics, management, political science, and linguistics emerged into cohesive and assertive departments by attracting respected professors and launching competitive graduate programs. The School of Humanities, Arts, and Social Sciences continued to develop under the successive terms of the more humanistically oriented presidents Howard W. Johnson and Jerome Wiesner between 1966 and 1980.

    Massachusetts Institute of Technology (US) ‘s involvement in military science surged during World War II. In 1941, Vannevar Bush was appointed head of the federal Office of Scientific Research and Development and directed funding to only a select group of universities, including MIT. Engineers and scientists from across the country gathered at Massachusetts Institute of Technology (US) ‘s Radiation Laboratory, established in 1940 to assist the British military in developing microwave radar. The work done there significantly affected both the war and subsequent research in the area. Other defense projects included gyroscope-based and other complex control systems for gunsight, bombsight, and inertial navigation under Charles Stark Draper’s Instrumentation Laboratory; the development of a digital computer for flight simulations under Project Whirlwind; and high-speed and high-altitude photography under Harold Edgerton. By the end of the war, Massachusetts Institute of Technology (US) became the nation’s largest wartime R&D contractor (attracting some criticism of Bush), employing nearly 4000 in the Radiation Laboratory alone and receiving in excess of $100 million ($1.2 billion in 2015 dollars) before 1946. Work on defense projects continued even after then. Post-war government-sponsored research at MIT included SAGE and guidance systems for ballistic missiles and Project Apollo.

    These activities affected Massachusetts Institute of Technology (US) profoundly. A 1949 report noted the lack of “any great slackening in the pace of life at the Institute” to match the return to peacetime, remembering the “academic tranquility of the prewar years”, though acknowledging the significant contributions of military research to the increased emphasis on graduate education and rapid growth of personnel and facilities. The faculty doubled and the graduate student body quintupled during the terms of Karl Taylor Compton, president of Massachusetts Institute of Technology (US) between 1930 and 1948; James Rhyne Killian, president from 1948 to 1957; and Julius Adams Stratton, chancellor from 1952 to 1957, whose institution-building strategies shaped the expanding university. By the 1950s, Massachusetts Institute of Technology (US) no longer simply benefited the industries with which it had worked for three decades, and it had developed closer working relationships with new patrons, philanthropic foundations and the federal government.

    In late 1960s and early 1970s, student and faculty activists protested against the Vietnam War and Massachusetts Institute of Technology (US) ‘s defense research. In this period Massachusetts Institute of Technology (US) ‘s various departments were researching helicopters, smart bombs and counterinsurgency techniques for the war in Vietnam as well as guidance systems for nuclear missiles. The Union of Concerned Scientists was founded on March 4, 1969 during a meeting of faculty members and students seeking to shift the emphasis on military research toward environmental and social problems. Massachusetts Institute of Technology (US) ultimately divested itself from the Instrumentation Laboratory and moved all classified research off-campus to the MIT (US) Lincoln Laboratoryfacility in 1973 in response to the protests. The student body, faculty, and administration remained comparatively unpolarized during what was a tumultuous time for many other universities. Johnson was seen to be highly successful in leading his institution to “greater strength and unity” after these times of turmoil. However six Massachusetts Institute of Technology (US) students were sentenced to prison terms at this time and some former student leaders, such as Michael Albert and George Katsiaficas, are still indignant about MIT’s role in military research and its suppression of these protests. (Richard Leacock’s film, November Actions, records some of these tumultuous events.)

    In the 1980s, there was more controversy at Massachusetts Institute of Technology (US) over its involvement in SDI (space weaponry) and CBW (chemical and biological warfare) research. More recently, Massachusetts Institute of Technology (US) ‘s research for the military has included work on robots, drones and ‘battle suits’.

    Recent history

    Massachusetts Institute of Technology (US) has kept pace with and helped to advance the digital age. In addition to developing the predecessors to modern computing and networking technologies, students, staff, and faculty members at Project MAC, the Artificial Intelligence Laboratory, and the Tech Model Railroad Club wrote some of the earliest interactive computer video games like Spacewar! and created much of modern hacker slang and culture. Several major computer-related organizations have originated at MIT since the 1980s: Richard Stallman’s GNU Project and the subsequent Free Software Foundation were founded in the mid-1980s at the AI Lab; the MIT Media Lab was founded in 1985 by Nicholas Negroponte and Jerome Wiesner to promote research into novel uses of computer technology; the World Wide Web Consortium standards organization was founded at the Laboratory for Computer Science in 1994 by Tim Berners-Lee; the MIT OpenCourseWare project has made course materials for over 2,000 Massachusetts Institute of Technology (US) classes available online free of charge since 2002; and the One Laptop per Child initiative to expand computer education and connectivity to children worldwide was launched in 2005.

    Massachusetts Institute of Technology (US) was named a sea-grant college in 1976 to support its programs in oceanography and marine sciences and was named a space-grant college in 1989 to support its aeronautics and astronautics programs. Despite diminishing government financial support over the past quarter century, MIT launched several successful development campaigns to significantly expand the campus: new dormitories and athletics buildings on west campus; the Tang Center for Management Education; several buildings in the northeast corner of campus supporting research into biology, brain and cognitive sciences, genomics, biotechnology, and cancer research; and a number of new “backlot” buildings on Vassar Street including the Stata Center. Construction on campus in the 2000s included expansions of the Media Lab, the Sloan School’s eastern campus, and graduate residences in the northwest. In 2006, President Hockfield launched the MIT Energy Research Council to investigate the interdisciplinary challenges posed by increasing global energy consumption.

    In 2001, inspired by the open source and open access movements, Massachusetts Institute of Technology (US) launched OpenCourseWare to make the lecture notes, problem sets, syllabi, exams, and lectures from the great majority of its courses available online for no charge, though without any formal accreditation for coursework completed. While the cost of supporting and hosting the project is high, OCW expanded in 2005 to include other universities as a part of the OpenCourseWare Consortium, which currently includes more than 250 academic institutions with content available in at least six languages. In 2011, Massachusetts Institute of Technology (US) announced it would offer formal certification (but not credits or degrees) to online participants completing coursework in its “MITx” program, for a modest fee. The “edX” online platform supporting MITx was initially developed in partnership with Harvard and its analogous “Harvardx” initiative. The courseware platform is open source, and other universities have already joined and added their own course content. In March 2009 the Massachusetts Institute of Technology (US) faculty adopted an open-access policy to make its scholarship publicly accessible online.

    Massachusetts Institute of Technology (US) has its own police force. Three days after the Boston Marathon bombing of April 2013, MIT Police patrol officer Sean Collier was fatally shot by the suspects Dzhokhar and Tamerlan Tsarnaev, setting off a violent manhunt that shut down the campus and much of the Boston metropolitan area for a day. One week later, Collier’s memorial service was attended by more than 10,000 people, in a ceremony hosted by the Massachusetts Institute of Technology (US) community with thousands of police officers from the New England region and Canada. On November 25, 2013, Massachusetts Institute of Technology (US) announced the creation of the Collier Medal, to be awarded annually to “an individual or group that embodies the character and qualities that Officer Collier exhibited as a member of the Massachusetts Institute of Technology (US) community and in all aspects of his life”. The announcement further stated that “Future recipients of the award will include those whose contributions exceed the boundaries of their profession, those who have contributed to building bridges across the community, and those who consistently and selflessly perform acts of kindness”.

    In September 2017, the school announced the creation of an artificial intelligence research lab called the MIT-IBM Watson AI Lab. IBM will spend $240 million over the next decade, and the lab will be staffed by MIT and IBM scientists. In October 2018 MIT announced that it would open a new Schwarzman College of Computing dedicated to the study of artificial intelligence, named after lead donor and The Blackstone Group CEO Stephen Schwarzman. The focus of the new college is to study not just AI, but interdisciplinary AI education, and how AI can be used in fields as diverse as history and biology. The cost of buildings and new faculty for the new college is expected to be $1 billion upon completion.

    The Caltech/MIT Advanced aLIGO (US) was designed and constructed by a team of scientists from California Institute of Technology (US), Massachusetts Institute of Technology (US) , and industrial contractors, and funded by the National Science Foundation (US) .

    MIT/Caltech Advanced aLigo .

    It was designed to open the field of gravitational-wave astronomy through the detection of gravitational waves predicted by general relativity. Gravitational waves were detected for the first time by the LIGO detector in 2015. For contributions to the LIGO detector and the observation of gravitational waves, two Caltech physicists, Kip Thorne and Barry Barish, and Massachusetts Institute of Technology (US) physicist Rainer Weiss won the Nobel Prize in physics in 2017. Weiss, who is also an Massachusetts Institute of Technology (US) graduate, designed the laser interferometric technique, which served as the essential blueprint for the LIGO.

    The mission of Massachusetts Institute of Technology (US) is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the Massachusetts Institute of Technology (US) community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

     
  • richardmitnick 9:03 am on September 4, 2020 Permalink | Reply
    Tags: "A step towards a better understanding of molecular dynamics", , Attosecond scale-1×10^18 of a second (one quintillionth of a second), , , Classical physics, Femtosecond 1x10^15 or 1⁄1 000 000 000 000 000 of a second; that is one quadrillionth- or one millionth of one billionth- of a second., , Polyatomic molecules – molecules made up of several atoms.,   

    From École Polytechnique Fédérale de Lausanne: “A step towards a better understanding of molecular dynamics” 


    From École Polytechnique Fédérale de Lausanne

    04.09.20 [9.4.20]
    Sarah Perrin

    1
    EPFL researchers, working at the boundary between classical and quantum physics, have developed a method for quickly spotting molecules with particularly interesting electron properties.

    Laser technology is giving scientists an ever-closer look into molecular structures, and this sometimes leads to very interesting surprises. At EPFL’s Laboratory of Theoretical Physical Chemistry (LCPT), a research team studying the dynamics of polyatomic molecules – molecules made up of several atoms – came across one such surprise. They found that electrons in these molecules move quite differently from what would be expected in isolated atoms.

    In isolated atoms, the oscillations of electron density are regular, but in most polyatomic molecules, the oscillations quickly become damped. This process is known as decoherence. However, in some molecules the oscillations last longer before decoherence sets in. The EPFL researchers developed a method which captures the physical mechanism behind decoherence, which consequently enables them to identify molecules with long-lasting coherences. Their method could prove interesting in the development of new electron-based technology or studying quantum effects in biomolecules. The findings were recently published in Physical Review Letters.

    “Electron movement takes place extremely rapidly – on an attosecond scale [1×10^18 of a second (one quintillionth of a second)] – so it’s very difficult to observe,” says Nikolay Golubev, a post-doc at LCPT and the study’s lead author. Furthermore, electron motion is strongly coupled to other processes in a molecule. This is why the research team incorporated additional piece of information into their study: the slower dynamics of the atomic nuclei and its influence on that of electrons. It was found that in most molecular structures the slow nuclear rearrangement damps the initially coherent oscillations of electrons and makes them disappear in a few femtoseconds [10^15 or ​1⁄1 000 000 000 000 000 of a second; that is, one quadrillionth, or one millionth of one billionth, of a second].

    A semiclassical approach

    To determine whether this phenomenon is actually taking place, the researchers developed a theoretical technique for an accurate and efficient description of the dynamics of electrons and nuclei after the molecules are ionized by ultrashort laser pulses. They used what’s considered a semiclassical approach in that it combines quantum features, like the simultaneous existence of several states, and classical features, namely classical trajectories guiding the molecular wavefunctions. This method allows scientists to detect the decoherence process much faster, making it easier to analyze many molecules and therefore spot ones that could potentially have long-lasting coherences.

    “Solving the Schrödinger equation for the quantum evolution of a polyatomic molecule’s wavefunction exactly is impossible, even with the world’s largest supercomputers,” says Jiri Vanicek, head of the LCPT. “The semiclassical approach makes it possible to replace the untreatable quantum problem with a still difficult, but solvable, problem, and provides a simple interpretation in which the molecule can be viewed as a ball rolling on a high-dimensional landscape.”

    To illustrate their method, the researchers applied it to two compounds: propiolic acid, whose molecules present long lasting coherence, and propiolamide (a propiolic acid derivative), in which the decoherence is fast. The team hopes to soon be able to test their method on hundreds of other compounds as well.

    Their discovery marks an important step towards a deeper understanding of molecular structures and dynamics, and stands to be a useful tool for observing long-lived electronic coherence in molecules. Backed with a better understanding of the decoherence process, scientists could one day be able to observe exactly how molecules act in biological tissue, for example, or create new kinds of electronic circuits.

    See the full article here .

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    EPFL campus

    EPFL is Europe’s most cosmopolitan technical university. It receives students, professors and staff from over 120 nationalities. With both a Swiss and international calling, it is therefore guided by a constant wish to open up; its missions of teaching, research and partnership impact various circles: universities and engineering schools, developing and emerging countries, secondary schools and gymnasiums, industry and economy, political circles and the general public.

     
  • richardmitnick 11:04 am on January 27, 2020 Permalink | Reply
    Tags: "Finding solutions amidst fractal uncertainty and quantum chaos", Classical physics, Dyatlov is now studying how the behavior of quantum systems over long time periods corresponds to that of classical systems., Math professor Semyon Dyatlov explores the relationship between classical and quantum physics., , , Semyon Dyatlov   

    From MIT News: “Finding solutions amidst fractal uncertainty and quantum chaos” 

    MIT News

    From MIT News

    January 25, 2020
    Jonathan Mingle

    1
    Semyon Dyatlov. Image: M. Scott Brauer

    Math professor Semyon Dyatlov explores the relationship between classical and quantum physics.

    Semyon Dyatlov calls himself a “mathematical physicist.”

    He’s an associate editor of the journal Probability and Mathematical Physics. His PhD dissertation advanced understanding of wave decay in black hole spacetimes. And much of his research focuses on developing new ways to understand the correspondence between classical physics (which describes light as rays that travel in straight lines and bounce off surfaces) and quantum systems (wherein light has wave-particle duality).

    So it may come as a surprise that, as a student growing up in Siberia, he didn’t study physics in depth.

    “Much of my work is deeply related to physics, even though I didn’t receive that much physics education as a student,” he says. “It took when I started working as a mathematician to slowly start understanding things like general relativity and modern particle physics.”

    A math-loving family, and inspiring mentors

    His mathematical education, however, has been extensive — and started early.

    Dyatlov was raised in a family of mathematicians. One of his two brothers is an applied mathematician. Both of his parents have math degrees. He grew up a five-minute walk away from the campus of Novosibirsk State University (NSU), a major academic research center in Siberia, where his father still teaches.

    “From a young age I was exposed to all kinds of mathematics,” he says. “There were journals and books lying around our house. I was very lucky that I both liked mathematics and was born into a family where a lot of mathematics was going on.”

    He can even trace his interest in microlocal analysis — his field of specialty today as an associate professor of mathematics at MIT — to conversations with his older brother decades ago. These talks sparked a fascination with partial differential equations, which Dyatlov studied as an undergraduate at NSU, where both his brother and father received their PhDs.

    Dyatlov went on to pursue graduate studies at the University of California at Berkeley. There his trajectory was influenced by a course he took during his first year with Professor Maciej Zworski on the theory of scattering resonances, which he explains are “pure states for systems in which energy can scatter to infinity.”

    It would prove to be a fruitful encounter. Zworski became Dyatlov’s dissertation advisor; a decade later, they are still collaborating. In addition to the many papers that they have written together, they co-authored a new textbook published by the American Mathematical Society in September.

    Zworski, who received both his bachelor’s degree and PhD in math from MIT, gave Dyatlov a particular problem to tackle early in his graduate studies.

    “There was back then a bit of a mystery surrounding how to apply scattering theory methods to black holes,” he recalls. The problem, which related to this mystery, grew into his dissertation’s detailed exploration of exponential wave decay in the context of general relativity.

    Of luck, collaboration, and “trapped trajectories”

    In December 2013, Dyatlov began a postdoc at MIT; by 2015 he had been hired as an assistant professor of mathematics. He is now an associate professor and was awarded tenure in 2019.

    “I sometimes feel I just got lucky many times,” Dyatlov says of his professional journey, from growing up in a family of mathematicians to finding influential mentors and collaborators like Zworski.

    Dyatlov is now studying how the behavior of quantum systems over long time periods corresponds to that of classical systems. Some of his recent research focuses on spectral gaps for open quantum chaotic systems.

    To help beginning students conceptualize it, he offers the analogy of striking a bell: “How does the shape of a bell determine how long its sound is sustained?” (Sometimes he uses MIT math department mugs instead.)

    The shape of the bell determines how long the sound is sustained. The difference lies in both the pitch of the sound, and in how long it can be heard. “You can study both,” he says, “but a natural question to ask is, no matter how you hit the bell, how long does it take for the sound to die out?”

    Classical physics might characterize what’s happening with the bell (or mug) as a phenomenon similar to light bouncing off a mirror: The sound bounces once off the bell and then escapes to infinity.

    “Mathematically what you hope to see is some exponential decay of energy, of the solution to a corresponding wave equation,” he explains. What interests Dyatlov is the rate of this decay, and whether, in some situations, there may not be any exponential decay at all.

    His recent work delves into what happens with these trajectories under conditions of “quantum chaos.”

    “Say you have waves bouncing off, and everything else escapes but you have a system — say the inside of a bowl — where these classical trajectories never leave. The thing that I study is a situation where you have in your system a fractal set of trapped trajectories,” he says.

    These trapped trajectories form a fractal set that appears “out of nowhere,” he says. “The fact that fractal sets appear from this was known well before my work, but it was still a surprise to me when I looked at it. Here, a fractal set appears naturally in a problem where you didn’t put in a fractal set.”

    That work led to his development of what he terms the “fractal uncertainty principle.” The classical uncertainty principle says you can’t pinpoint both the position and momentum of a quantum particle. Dyatlov posited a form of this principle for this fractal set of trapped trajectories.

    “I figured out one might be able to solve this wave decay question — this question about partial differential equations, about classical-quantum correspondence, about wave dynamics, and chaotic dynamics — but the component you need is this new kind of fractal uncertainty principle,” he says.

    Translation and toolboxes

    Pursuing this question required him to branch out into different fields of math, which lay outside his own training. In that pursuit, he caught another “lucky break:” MIT professor of mathematics Larry Guth suggested he talked with Joshua Zahl, a postdoc who had been thinking independently about a related question, from his own field of additive combinatorics. Applying their respective techniques, they developed a proof for exponential decay in some specific fractal sets and wrote a paper together on the subject. A couple years later — in yet another “lucky” collaboration — Dyatlov worked with the late Jean Bourgain, a renowned mathematician at the Institute for Advanced Study, to prove the fractal uncertainty principle for the general case of these sets.

    “You have your toolbox, and you try to get as much out of it as you can for a problem,” he says, but sometimes you have to seek out new tools. “MIT is a great place for that.”

    That act of reaching across fields is fundamental to the practice of mathematics, he says. The book that he recently published with Zworski opens with a quote from Goethe: “Mathematicians are Frenchmen of sorts: Whatever one says to them they translate into their own language and then it becomes something entirely different.”

    Dyatlov sees a connection between this epigraph and his own forays into the correspondence between math and physics.

    “It’s an ironic take on that,” he says. “There’s a natural repelling force for math and physics to diverge into separate fields, because we do things so differently. Experimental physicists have to respect the reality of situation, and have to think about what you can model in a lab. As a mathematician, you focus on things you can prove. You have to distill and translate the physical phenomena into theorems.”

    “It’s up to people in communities to create an attracting force to work together and bridge this divide.”

    See the full article here .


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    The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

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  • richardmitnick 1:12 pm on April 9, 2019 Permalink | Reply
    Tags: "In quantum breakthrough scientists demonstrate ‘one-way street’ for energy flow", , , Classical physics, , ,   

    From University of Chicago: “In quantum breakthrough, scientists demonstrate ‘one-way street’ for energy flow” 

    U Chicago bloc

    From University of Chicago

    Apr 4, 2019
    A. A. Clerk

    1
    Copyright shutterstock.com

    In a new study, scientists found a method to create a controllable one-way channel for the flow of vibrational energy and heat.

    A basic rule in our lives is that if energy can flow in one direction, then it can also flow in the reverse direction. For example, if you open a window and yell at someone outside, you also can hear if they yell back. But what if there was a way to create a “one-way street” for mechanical energy that only allows heat and sound to flow in one direction?

    Finding new ways to break this basic symmetry has sparked the interest of scientists and engineers in recent years; such one-way streets could be extremely useful in applications ranging from quantum computing to cooling in electronics and devices.

    A breakthrough experiment involving researchers with the Institute for Molecular Engineering at the University of Chicago and Yale University demonstrated that by using light to mediate the interaction between mechanical systems, they can create a controllable, one-way channel for the flow of vibrational energy and heat.

    The study, published April 3 in Nature, was based on an idea developed earlier by the University of Chicago team [Physical Review X] and proves that the basic theory works. It also shows that the ideas can be implemented in a simple, compact system that could be incorporated in new devices.

    2
    Schematic image of the experimental device. Credit: Jack Sankey

    “This is a really exciting resource that can be used in both classical and quantum contexts,” said study co-author Aashish Clerk, a professor in molecular engineering at the University of Chicago who developed the theory. “This research could open the door for many new studies.”

    Breaking symmetry by using light

    The principle that says energy and information exchange between two systems via a two-way street is known as “reciprocity,” and it is a fundamental rule in most physical systems. Breaking this symmetry is crucial in a number of different applications. For example, by preventing a backward flow of energy, one could protect a delicate signal source from corruption, or cool a system by preventing unwanted heating.

    It’s especially important in quantum computation, in which scientists harness quantum phenomena to enable powerful new kinds of information processing. Breaking this symmetry ensures delicate quantum processors are not destroyed during the readout process.

    In their experiment, researchers used a tiny vibrating membrane as the mechanical system. Much like a drumhead, this membrane could vibrate in several distinct ways, each with a distinct resonant frequency.

    The researchers’ goal was to engineer a one-way flow of energy between two of these vibrational modes. To do this, the membrane was placed in a structure called an optical cavity, with two parallel mirrors designed to trap light. By shining light on the cavity using lasers, the researchers were able to use light as a medium for transferring mechanical energy between two vibrational modes. When the lasers were tuned carefully (in a way predicted by Clerk’s theory), this transfer mechanism was completely directional.

    From theory to lab to the quantum level

    The experiment was based on basic theoretical concepts developed by Clerk and his former postdoc Anja Metelmann (now at the Freie University in Berlin).

    “You can come up with a lot of ideas that are exciting in terms of the basic theory and concepts, but often there is a gap between these abstract ideas and what you can actually build and realize in the lab,” Clerk said. “To me, it is exciting that our proposal was realized, and that the experimentalists had enough control over their system to make it work.”

    The approach used in the experiment to achieve a one-way interaction—mechanical vibrations interacting with light—could pave the way for designing new devices targeting a variety of applications, ranging from mitigating heat flow to new kinds of communication systems. These unusual one-way interactions also have interesting fundamental implications.

    As a theoretical physicist who focuses on quantum systems, Clerk is particularly interested in studying arrays where many quantum systems interact with one another in a unidirectional manner. This could be a powerful way to generate the unusual kinds of quantum states that are needed for quantum communication and quantum computation.

    Other authors on the paper include Jack Harris, Haitan Xu and Luyao Jiang of Yale University.

    Clerk is working with the Polsky Center for Entrepreneurship and Innovation at the University of Chicago to advance his discoveries.

    See the full article here .

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    U Chicago Campus

    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

    The University of Chicago is an urban research university that has driven new ways of thinking since 1890. Our commitment to free and open inquiry draws inspired scholars to our global campuses, where ideas are born that challenge and change the world.

    We empower individuals to challenge conventional thinking in pursuit of original ideas. Students in the College develop critical, analytic, and writing skills in our rigorous, interdisciplinary core curriculum. Through graduate programs, students test their ideas with UChicago scholars, and become the next generation of leaders in academia, industry, nonprofits, and government.

    UChicago research has led to such breakthroughs as discovering the link between cancer and genetics, establishing revolutionary theories of economics, and developing tools to produce reliably excellent urban schooling. We generate new insights for the benefit of present and future generations with our national and affiliated laboratories: Argonne National Laboratory, Fermi National Accelerator Laboratory, and the Marine Biological Laboratory in Woods Hole, Massachusetts.

    The University of Chicago is enriched by the city we call home. In partnership with our neighbors, we invest in Chicago’s mid-South Side across such areas as health, education, economic growth, and the arts. Together with our medical center, we are the largest private employer on the South Side.

    In all we do, we are driven to dig deeper, push further, and ask bigger questions—and to leverage our knowledge to enrich all human life. Our diverse and creative students and alumni drive innovation, lead international conversations, and make masterpieces. Alumni and faculty, lecturers and postdocs go on to become Nobel laureates, CEOs, university presidents, attorneys general, literary giants, and astronauts.

     
  • richardmitnick 8:02 am on July 24, 2018 Permalink | Reply
    Tags: , Classical physics, , , ,   

    From JHU HUB: “Evidence revealed for a new property of quantum matter” 

    Johns Hopkins

    From JHU HUB

    June 12, 2018 [Where has this been? Just popped into JHU email.]

    A theorized but never-before detected property of quantum matter has now been spotted in the lab, a team led by a Johns Hopkins scientist reports.

    The study findings, published online in the journal Science, show that a particular quantum material first synthesized 20 years ago, called k-(BEDT-TTF)2Hg(SCN)2 Br, behaves like a metal but is derived from organic compounds. The material can demonstrate electrical dipole fluctuations—irregular oscillations of tiny charged poles on the material—even in extremely cold conditions, in the neighborhood of minus 450 degrees Fahrenheit.

    “What we found with this particular quantum material is that, even at super-cold temperatures, electrical dipoles are still present and fluctuate according to the laws of quantum mechanics,” said Natalia Drichko, associate research professor in physics at Johns Hopkins University and the study’s senior author.

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    Natalia Drichko in her lab. Image credit: Jon Schroeder

    “Usually we think of quantum mechanics as a theory of small things, like atoms, but here we observe that the whole crystal is behaving quantum-mechanically.”

    Classical physics describes most of the behavior of physical objects we see and experience in everyday life. In classical physics, objects freeze at extremely low temperatures, Drichko said. In quantum physics—science that primarily describes the behavior of matter and energy at the atomic level and smaller—there is motion even at those frigid temperatures, Drichko said.

    “That’s one of the major differences between classical and quantum physics that condensed matter physicists are exploring,” she said.

    An electrical dipole is a pair of equal but oppositely charged poles separated by some distance. Such dipoles can, for instance, allow a hair to “stick” to a comb through the exchange of static electricity: Tiny dipoles form on the edge of the comb and the edge of the hair.

    2
    The structure of the crystal that was studied in the research; an individual molecule is highlighted in red. Image credit: Institute for Quantum Matter/JHU

    Drichko’s research team observed the new extreme-low-temperature electrical state of the quantum matter in Drichko’s Raman spectroscopy lab, where the key work was done by graduate student Nora Hassan. Team members focused light on a small crystal of the material. Employing techniques from other disciplines, including chemistry and biology, they found proof of the dipole fluctuations.

    The study was possible because of the team’s home-built, custom-engineered spectrometer, which increased the sensitivity of the measurements 100 times.

    The unique quantum effect the team found could potentially be used in quantum computing, a type of computing in which information is captured and stored in ways that take advantage of the quantum states of matter.

    See the full article here .


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    About the Hub

    We’ve been doing some thinking — quite a bit, actually — about all the things that go on at Johns Hopkins. Discovering the glue that holds the universe together, for example. Or unraveling the mysteries of Alzheimer’s disease. Or studying butterflies in flight to fine-tune the construction of aerial surveillance robots. Heady stuff, and a lot of it.

    In fact, Johns Hopkins does so much, in so many places, that it’s hard to wrap your brain around it all. It’s too big, too disparate, too far-flung.

    We created the Hub to be the news center for all this diverse, decentralized activity, a place where you can see what’s new, what’s important, what Johns Hopkins is up to that’s worth sharing. It’s where smart people (like you) can learn about all the smart stuff going on here.

    At the Hub, you might read about cutting-edge cancer research or deep-trench diving vehicles or bionic arms. About the psychology of hoarders or the delicate work of restoring ancient manuscripts or the mad motor-skills brilliance of a guy who can solve a Rubik’s Cube in under eight seconds.

    There’s no telling what you’ll find here because there’s no way of knowing what Johns Hopkins will do next. But when it happens, this is where you’ll find it.

    Johns Hopkins Campus

    The Johns Hopkins University opened in 1876, with the inauguration of its first president, Daniel Coit Gilman. “What are we aiming at?” Gilman asked in his installation address. “The encouragement of research … and the advancement of individual scholars, who by their excellence will advance the sciences they pursue, and the society where they dwell.”

    The mission laid out by Gilman remains the university’s mission today, summed up in a simple but powerful restatement of Gilman’s own words: “Knowledge for the world.”

    What Gilman created was a research university, dedicated to advancing both students’ knowledge and the state of human knowledge through research and scholarship. Gilman believed that teaching and research are interdependent, that success in one depends on success in the other. A modern university, he believed, must do both well. The realization of Gilman’s philosophy at Johns Hopkins, and at other institutions that later attracted Johns Hopkins-trained scholars, revolutionized higher education in America, leading to the research university system as it exists today.

     
  • richardmitnick 4:50 pm on June 28, 2017 Permalink | Reply
    Tags: Classical physics, Transferring New Energy to an Old Rule: Pushing the Boundaries of Classical Physics,   

    From Yale: “Transferring New Energy to an Old Rule: Pushing the Boundaries of Classical Physics” 

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    Yale University

    January 16, 2017
    Chunyang Ding

    1
    Cover image: A synchrotron, similar to the one pictured above, was used to determine the composition of fossils, an analysis key to understanding the preservational features of the Tully Monster. Image courtesy of John O’Neill

    Time after time, brilliant scientists make claims about science’s future that prove completely wrong. In a quote often misattributed to Lord Kelvin, Albert Michelson famously declared that “there is nothing new to be discovered in physics now; all that remains is more and more precise measurement.” Classical mechanics, the tradition of physics that originated with Newton, Kepler, and Galileo, is often seen as something we already understand, and something we have understood for a long time. This is simply not true. Even today, new discoveries made with classical mechanics are transforming the world of science as we know it.

    In a recent breakthrough, a Yale physics lab shows new behaviors in a phenomenon that some had considered fully understood. Associate professor of physics Jack Harris and post-doctoral researcher Haitan Xu report in Nature their use of ultra-precise lasers and tiny vibrating sheets that appear to violate classical predictions. Their experiment, transferring energy by very slowly tuning the vibrations, has major implications for a decades-old theorem in mechanics: the adiabatic theorem. This newly discovered phenomenon occurs in all systems with friction, and may fundamentally shift the way physicists view systems.

    A dance for the ages

    Although Xu’s research focuses on how energy can be transferred between two different regions, the core of this new research deals with systems, a very general way of describing things that interact. Most things in the world are systems: the traffic through a busy city, the movement of the planets, or even a large ballroom dance.

    In a ballroom dance, each person on the dance floor obeys the rules of the dance, and as they move, they interact with other people harmoniously. There might be a set number of dance moves that eventually bring them back to the starting point. Essentially, Xu’s research found that there are certain moves that when danced “clockwise,” return you to the same position, but when danced “counter-clockwise,” present you with a new partner. This non-symmetrical form has serious implications for any system, and offers a new way that scientists could control these systems.

    1
    Any system, even our solar system, can be represented in a parameter space, where different parameters are plotted against each other. Through careful control, the Harris lab was able to navigate the parameters of their vibrating membrane around an exceptional point, showing an extension to the adiabatic theorem. Image courtesy of Sida Tang

    The research provides an extension of the adiabatic theorem, a theorem that governs how systems change as the parameters of the systems change. These parameters can be any controlled quality of the system — the dance moves performed, the tension in a wire, or the controls in a computer. The adiabatic theorem says that if the parameters are slowly restored to their original state, the system will appear to have not changed at all. This is very powerful in physics, because for a certain experiment on a system, scientists can restore previous states without being concerned exactly in what way the parameters changed. Yet, it is not very exciting. After all, you only end up where you begin.

    Imagine for a moment that we had a small dial allowing us to change the masses of Jupiter and the Sun. Through our understanding of the laws of gravity, we could predict how the orbits of the planet change if Jupiter became more massive and if the Sun became less massive. The paths of the planets may become chaotic, but the adiabatic theorem provides a simple solution: when all of the parameters are back to where they began, the system would appear to have never changed.

    However, there is one caveat to the above examples. The only way that the adiabatic theorem has been proven is through assuming systems that do not have any friction, or energy loss. Only in those cases does the adiabatic theorem work as expected. Still, physicists applied this theorem to systems with friction by assuming such systems would behave very similarly to those without friction. What physicists did not expect, however, was that the system could change completely. Although mathematicians predicted anomalies using what they called “exceptional points,” physicists were unable to see these anomalies in actual systems — until now.

    Tiny vibrating membranes

    While the previous systems may be simple to imagine, they would be nearly impossible to actually control and measure. In order to actually see the effects of the adiabatic theorem, Xu’s research involved vibrating a tiny membrane between two mirrors while using lasers both to control and to measure the vibrations of the membrane. The reason this is considered a system is because the membrane has two vibrational modes, or methods of vibration, and the frequency of each vibration can be controlled by the laser. Vibrational modes are like vertical waves and a horizontal waves that pass by each other, and can be thought of as two separate strings, each vibrating independently.

    Vibrating strings are familiar to anyone who has played a string instrument, whether it be a guitar, a violin, or an erhu. When you pluck a single string, the other strings do not react, as each string has a different resonating frequency. However, if you tune two strings to have the same resonating frequency, the vibrating energy can transfer from one string to the other. In this experiment, the resonating frequencies are being changed so that the two different strings are first tuned together, and then returned to their original resonating frequencies. If we then apply the adiabatic theorem, we would predict that whatever vibrations are in the strings now are the same as the vibrations in the strings that we started with.

    3
    The lab group, (Luyao Jiang, Haitan Xu, David Mason and Professor Jack Harris in 8, Professor Jack Harris, Haitan Xu, David Mason and Luyao Jiang in 9) pose before their experimental apparatus. Along with the Doppler group from the Vienna University of Technology, this lab was the first to discover experimental proof for the exceptional points. Image courtesy of George Iskander

    However, Xu’s research group discovered that this is not always the case in a system that has some amount of friction. In rare situations that involve the “exceptional point” in parameter space, the energy can end up transferring from the first string to the second string. Every time the parameters were changed counter-clockwise around the exceptional point, they found drastic changes to the final systems. They found that whenever the parameters created a path that encircled the exceptional point, this change happened, regardless of the actual shape of the path.

    Teleporting between different sheets

    Exceptional points are fairly difficult to imagine for a good reason: They are the result of two 2D sheets intersecting each other in a 4D space. One way to picture these exceptional points is a fire pole connecting two floors of a fire station. While each floor is distinct, they “meet” at the fire pole. However, oddly, when you walk counter-clockwise around the pole on the first floor, you would find yourself on the second floor, without having climbed the pole at all! The phenomenon here is due to the bizarre spatial geometry, similar to shapes like a Mobius strip or a Klein bottle. The exceptional points are mathematically similar, connecting surfaces that appear to be separated.

    The example with the fire station may be hard to visualize, but the actual experiment is even more abstract, as there is no actual movement around anything. Instead, when the parameters of the vibrations travel in this loop, the energy of the system shifts. The experimental group was able to quantitatively measure the energy differences in this single membrane by spying on the vibrations with a low-powered laser even as a high-powered laser changed the parameters. This research, the first of its type, provides solid evidence that the mathematicians were right: Exceptional points exist in parameter space, and physicists can utilize them to control the system.

    In the same issue of Nature, a separate group also published on this topic, but the group used a completely different method. While the Yale group was able to dynamically change the vibrations using the laser, a group from the Vienna University of Technology led by Jorg Doppler found similar effects through pre-fabricated waveguides, which are equally impressive in the ability to control waves. Together with the Xu research, these experiments provide the first empirical proof of exceptional points.

    Taking control of our world

    4
    Like a Klein bottle, the geometries of parameter space may seem to be non-orientable, allowing for this phenomenon to occur. This bizarre discovery shows experimentally what was previously hypothesized mathematically. Image courtesy of Wikimedia

    The most powerful implication of this new research may be in its application for controlling systems. The adiabatic theorem, as well as this extension of the theorem, are particularly robust. They do not seem to care what path you take, as long as you return to the same position. This property is analogous to blindly driving through a dark two-lane icy tunnel, but finding that you always end up on the right side of the road at the end. These robust theorems are extremely helpful for experiments, especially in preventing disruptions to the system. “It’s a new type of control over really pristine systems,” Harris said.

    Even the classical adiabatic theorem and its offshoots are being used to predict magnetic effects and provide a deeper understanding for many quantum phenomena. This new extension of the adiabatic theorem will provide insight for physicists as they apply it to other systems, like NMRs and MRIs. In fact, this extended adiabatic theorem, as a fundamental physical theorem, could be more broadly applied to any system — so this research could theoretically be applied to anything that can be modeled as a system. However, this isn’t the end of the line on this research for the Harris lab; they have a paper forthcoming regarding the application of this technique to very different kinds of vibrations.

    Our understanding of every branch of science is constantly evolving and changing. Just when we think we understand everything about a field, we realize that particles can interact with themselves, that the fabric of space and time can stretch, and that the universe is expanding. Classical mechanics is no different; the extended adiabatic theorem from this study shows just that. At a certain point, we might as well expect to be surprised. If you find yourself walking around a fire pole on the first floor and ending up on the second, don’t be alarmed. Bizarre Twilight Zone scenarios like that are what can help physicist control, bend, and structure our world — no matter how strange those truths may be.

    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.

     
  • richardmitnick 12:19 pm on December 12, 2016 Permalink | Reply
    Tags: , Classical physics, , , ,   

    From Hopkins and Rutgers: “Between two worlds: Exotic insulator may hold clue to key mystery of modern physics” 

    Johns Hopkins
    Johns Hopkins University

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    Rutgers University

    Dec 6, 2016
    Arthur Hirsch

    Scientists experiment with material that straddles world of classical physics and hidden quantum realm

    Experiments using laser light and pieces of gray material the size of fingernail clippings may offer clues to a fundamental scientific riddle: what is the relationship between the everyday world of classical physics and the hidden quantum realm that obeys entirely different rules?

    1
    N. Peter Armitage

    “We found a particular material that is straddling these two regimes,” said N. Peter Armitage, an associate professor of physics at Johns Hopkins University who led the research for the paper just published in the journal Science. Six scientists from Johns Hopkins and Rutgers University were involved in the work on materials called topological insulators, which can conduct electricity on their atoms-thin surface, but not in their insides.

    Topological insulators were predicted in the 1980s, first observed in 2007, and have been studied intensively since. Made from any number of hundreds of elements, these materials have the capacity to show quantum properties that usually appear only at the microscopic level, but here appear in a material visible to the naked eye.

    The experiments reported in Science establish these materials as a distinct state of matter “that exhibits macroscopic quantum mechanical effects,” Armitage said. “Usually we think of quantum mechanics as a theory of small things, but in this system quantum mechanics is appearing on macroscopic length scales. The experiments are made possible by unique instrumentation developed in my laboratory.”

    In the experiments reported in Science, the elements bismuth and selenium make up dark gray material samples—each a few millimeters long and of different thicknesses—that were hit with “THz” light beams that are invisible to the unaided eye. Researchers measured the reflected light as it moved through the material samples and found indicators of a quantum state of matter.

    Specifically, they found that as the light was transmitted through the material, the wave rotated a specific amount, which is related to physical constants that are usually only measurable in atomic scale experiments. The amount matched predictions of what would be possible in this quantum state.

    The results add to scientists’ understanding of topological insulators, but also may contribute to the larger subject that Armitage says is the central question of modern physics: what is the relationship between the macroscopic classical world, and the microscopic quantum world from which it arises?

    Scientists since the early 20th century have struggled with the question of how one set of physical laws governing objects above a certain size can co-exist alongside a different set of laws governing the atomic and subatomic scale. How does classical mechanics emerge from quantum mechanics, and where is the threshold that divides the realms?

    Those questions remain to be answered, but topological insulators could be part of the solution.

    “It’s a piece of the puzzle,” said Armitage, who worked on the experiments along with Liang Wu, who was a graduate student at Johns Hopkins when the work was done; Maryam Salehi of the Rutgers University Department of Material Science and Engineering; and Nikesh Koirala, Jisoo Moon, and Sean Oh of the Rutgers University Department of Physics and Astronomy.

    See the full article here .

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    rutgers-campus

    Rutgers, The State University of New Jersey, is a leading national research university and the state’s preeminent, comprehensive public institution of higher education. Rutgers is dedicated to teaching that meets the highest standards of excellence; to conducting research that breaks new ground; and to providing services, solutions, and clinical care that help individuals and the local, national, and global communities where they live.

    Johns Hopkins Campus

    The Johns Hopkins University opened in 1876, with the inauguration of its first president, Daniel Coit Gilman. “What are we aiming at?” Gilman asked in his installation address. “The encouragement of research … and the advancement of individual scholars, who by their excellence will advance the sciences they pursue, and the society where they dwell.”

    The mission laid out by Gilman remains the university’s mission today, summed up in a simple but powerful restatement of Gilman’s own words: “Knowledge for the world.”

    What Gilman created was a research university, dedicated to advancing both students’ knowledge and the state of human knowledge through research and scholarship. Gilman believed that teaching and research are interdependent, that success in one depends on success in the other. A modern university, he believed, must do both well. The realization of Gilman’s philosophy at Johns Hopkins, and at other institutions that later attracted Johns Hopkins-trained scholars, revolutionized higher education in America, leading to the research university system as it exists today.

     
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