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  • richardmitnick 12:50 pm on May 8, 2020 Permalink | Reply
    Tags: Atomic comagnetometer, , , Bose-Einstein condensate, , ,   

    From physicsworld.com: “Ultracold atomic comagnetometer joins the search for dark matter” 

    From physicsworld.com

    05 May 2020
    Hamish Johnston

    In a spin: illustration of a Bose–Einstein condensate of rubidium atoms in two different quantum states. (Courtesy: ICFO/ P Gomez and M Mitchell)

    A new atomic comagnetometer that could be used to detect hypothetical dark matter particles called axions has been created by physicists in Spain. The sensor uses two different quantum states of ultracold rubidium atoms to cancel out the effect of ambient magnetic fields, allowing physicists to focus on exotic spin-dependent interactions that may involve axions.

    Dark matter is a mysterious substance that appears to account for about 85% of the matter in the universe – the other 15% being normal matter such as atoms and molecules. While myriad astrophysical observations point to the existence of dark matter, physicists have very little understanding of its precise nature.

    Some dark matter could comprise hypothetical particles called axions, which were first proposed in the 1970s to solve a problem in quantum chromodynamics. If dark matter axions do exist, they could mediate exotic interactions between quantum-mechanical spins – in analogy to how photons mediate conventional magnetic interactions between spins.

    Two detectors

    These exotic interactions would be weak, but in principle they could be measured using an atomic comagnetometer, which comprises two different magnetic-field detectors that are in the same place. The device is set so that the effects of ambient magnetic fields in the two detectors can be cancelled out. So, a residual signal in the comagnetometer could be the result of an exotic interaction between atomic spins within the detector itself.

    The new comagnetometer was created at the Institute of Photonic Sciences in Barcelona by Pau Gomez, Ferran Martin, Chiara Mazzinghi, Daniel Benedicto Orenes, Silvana Palacios and Morgan Mitchell. The two different detectors are rubidium-87 atoms that are in two different spin states that respond in different ways to magnetic fields.

    Near absolute zero

    The atoms are in a gas that is chilled to near absolute zero to create a Bose-Einstein condensate (BEC). In this state the atoms are relatively immune to being jostled about by thermal interactions. This means that for several seconds the spins can respond in a coherent way to spin interactions. The BEC is also very small – just 10 microns in diameter – which boosts its performance as a comagnetometer and means that short-range axion interactions can be probed.

    The response of the spins to a magnetic field is measured by firing a polarized of a beam of light at the BEC and measuring how its polarization is rotated. By comparing measurements on the two different spin states, the effect of ambient magnetic fields can be removed, allowing the team to look for any exotic interactions that are affecting the spins.

    Although no evidence of axions has been found by the device so far, the team has shown that the comagnetometer is highly immune to noise from ambient magnetic fields. They say that it could be run at a sensitivity on par with other types of comagnetometers that are currently looking for axions. The device has already been used to measure conventional spin interactions between the ultracold atoms and the team says that other potential applications include spin amplification, which could be used to study quantum fluctuations.

    The comagnetometer is described in Physical Review Letters.

    See the full article here .

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    We engage with policymakers and the general public to develop awareness and understanding of the value of physics and, through IOP Publishing, we are world leaders in professional scientific communications.
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  • richardmitnick 1:09 pm on February 4, 2019 Permalink | Reply
    Tags: A lot of fascinating phenomena occur when you collide two condensates, , , Bose-Einstein condensate, Mini quantum fluid collider, New quantum system could help design better spintronics, , , Using this system researchers can literally turn spin-orbit coupling on and off   

    From Purdue University: “New quantum system could help design better spintronics” 

    From Purdue University

    January 29, 2019

    Kayla Zacharias

    Purdue University researchers used lasers to trap and cool atoms down to nearly absolute zero, at which point they become a quantum fluid known as Bose-Einstein condensate, and collided condensates with opposite spins. (Purdue University photo/Purdue Quantum Center)

    Researchers have created a new testing ground for quantum systems in which they can literally turn certain particle interactions on and off, potentially paving the way for advances in spintronics.

    Spin transport electronics have the potential to revolutionize electronic devices as we know them, especially when it comes to computing. While standard electronics use an electron’s charge to encode information, spintronic devices rely on another intrinsic property of the electron: its spin.

    Spintronics could be faster and more reliable than conventional electronics, as these devices use less power. However, the field is young and there are many questions researchers need to solve to improve their control of spin information. One of the most complex questions plaguing the field is how the signal carried by particles with spin, known as spin current, decays over time.

    “The signal we need to make spintronics work, and to study these things, can decay. Just like we want good cell phone service to make a call, we want this signal to be strong,” said Chuan-Hsun Li, a graduate student in electrical and computer engineering at Purdue University. “When spin current decays, we lose the signal.”

    In the real world, electrons don’t exist independently of everything around them and behave exactly how we expect them to. They interact with other particles and among different properties within themselves. The interaction between a particle’s spin (an intrinsic property) and momentum (an extrinsic property) is known as spin-orbit coupling.

    According to a new paper in Nature Communications, spin-orbit coupling and interactions with other particles can dramatically enhance spin current decay in a quantum fluid called Bose-Einstein condensate (BEC).

    “People want to manipulate spin formation so we can use it to encode information, and one way to do this is to use physical mechanisms like spin-orbit coupling,” Li said. “However, this can lead to some drawbacks, such as the loss of spin information.”

    The experiment was done in the lab of Yong Chen, a professor of physics and astronomy, and electrical and computer engineering at Purdue, where his team created something like a mini particle collider for BECs. Using lasers, Rubidium-87 atoms within a vacuum chamber were trapped and cooled nearly to absolute zero. (Physics junkies may recall that laser cooling technologies won the Nobel Prize in physics in 1997. Laser trapping won the Prize in 2018.)

    At this point, the atoms become a BEC: the coldest and most mysterious of the five states of matter. As atoms get colder, they start to display wave-like properties. In this quantum state, they have an identity crisis; they overlap with one another and stop behaving like individuals. Although BEC isn’t technically a gas, this might be the easiest way to picture it – physicists casually refer to it as quantum fluid or quantum gas.

    Inside the mini quantum fluid collider, Chen’s team sent two BECs with opposite spins smashing into one another. Like two clouds of gas would, they partially penetrate each other, delivering a spin current.

    “A lot of fascinating phenomena occur when you collide two condensates. Originally, they’re superfluid, but when they collide, part of the friction can turn them to thermal gas,” Chen said. “Because we can control every parameter, this is a really efficient system to study these kinds of collisions.”

    Using this system, researchers can literally turn spin-orbit coupling on and off, which allows them to isolate its effect on spin current decay. This can’t be done with electrons in solid-state materials, which is part of what makes this system so powerful, Chen said.

    So-called quantum gas is the cleanest system man can make. There’s no disorder, which makes it possible to create a pure spin current and study its properties. Chen hopes to keep using this experimental testing ground and their bosonic spin current to further explore many fundamental questions in spin transport and quantum dynamics.

    “One important challenge for spintronics and other related quantum technologies is to reduce decay so we can propagate spin information over longer distances, for longer times,” he said. “With this new knowledge of the role of spin-orbit coupling, this may help people gain new insights to reduce spin decay and potentially also design better spintronic devices.”

    This research was supported by Purdue University, the Purdue Research Foundation, the National Science Foundation, the U.S. Department of Energy, Department of Defense and Hong Kong Research Council.

    See the full article here .


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    Purdue University is a public research university in West Lafayette, Indiana, and the flagship campus of the Purdue University system. The university was founded in 1869 after Lafayette businessman John Purdue donated land and money to establish a college of science, technology, and agriculture in his name. The first classes were held on September 16, 1874, with six instructors and 39 students.

    The main campus in West Lafayette offers more than 200 majors for undergraduates, over 69 masters and doctoral programs, and professional degrees in pharmacy and veterinary medicine. In addition, Purdue has 18 intercollegiate sports teams and more than 900 student organizations. Purdue is a member of the Big Ten Conference and enrolls the second largest student body of any university in Indiana, as well as the fourth largest foreign student population of any university in the United States.

  • richardmitnick 10:49 am on October 27, 2018 Permalink | Reply
    Tags: , Bose star, Bose-Einstein condensate, , , Institute for Nuclear Physics of the Russian Academy of Sciences, , Russian physicists observe dark matter forming droplets   

    From EurekaAlert: “Russian physicists observe dark matter forming droplets” 


    From EurekaAlert


    Dmitry Levkov

    Researchers developed a mathematical model describing motion of dark matter particles inside the smallest galaxy halos.

    Caterpillar Project A Milky-Way-size dark-matter halo and its subhalos circled, an enormous suite of simulations . Griffen et al. 2016

    They observed that over time, the dark matter may form spherical droplets of quantum condensate. Previously this was considered impossible, as fluctuations of the gravity field produced by dark matter particles were ignored. The study is published in Physical Review Letters.

    Dark matter is a hypothetical form of matter that does not emit electromagnetic radiation.

    Women in STEM – Vera Rubin

    Fritz Zwicky discovered Dark Matter when observing the movement of the Coma Cluster

    Coma cluster via NASA/ESA Hubble

    But most of the real work was done by Vera Rubin

    Fritz Zwicky from http:// palomarskies.blogspot.com

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science)

    Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL)

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu

    This property hinders dark matter searches and makes it hard even to prove its existence. The speed of dark matter particles is low, which is why they are retained by galaxies. They interact with each other and with the ordinary matter so weakly that only their gravity field can be sensed, otherwise the dark matter does not manifest itself in any way. Each galaxy is surrounded by a dark matter shell (halo) of much larger size and mass.

    Left image: initial moment, when the gas is mixed; right image: the moment shortly after the formation of a Bose star. The colour indicates density: white-blue-green-yellow, from sparse to dense. Credit Dmitry Levkov

    Most cosmologists believe that dark matter particles have large mass, hence their speed is high. Yet, back in the 1980s it was realized that under special conditions these particles may be produced in the early Universe with almost zero speed, regardless of their mass. They might also be very light. As a consequence, the distances at which the quantum nature of these particles becomes apparent can be huge. Instead of the nanometer scales that are usually required to observe quantum phenomena in laboratories, the “quantum” scale for such particles may be comparable to the size of the central part of our galaxy.

    The researchers observed that the dark matter particles, if they are bosons with sufficiently small mass, may form a Bose-Einstein condensate in the small galaxy halos or in even smaller substructures due to their gravitational interactions. Such substructures include halos of dwarf galaxies – systems of several billion stars bound together by gravitational forces, and miniclusters – very small systems formed only by dark matter. The Bose-Einstein condensate is a state of quantum particles in which they all occupy the lowest energy level, having the smallest energy. The Bose-Einstein condensate can be produced in the lab at low temperatures from ordinary atoms. This state of matter exhibits unique properties, such as superfluidity: the ability to pass through tiny cracks or capillaries without friction. Light dark matter in the galaxy has low speed and huge concentration. Under these conditions, it should eventually form a Bose-Einstein condensate. But in order for this to happen, dark matter particles must interact with each other, while as far as we know, they interact only gravitationally.

    “In our work, we simulated motion of a quantum gas of light gravitationally interacting dark matter particles. We started from a virialized state with maximal mixing, which is kind of opposite to the Bose-Einstein condensate. After a very long period, 100,000 times longer than the time needed for a particle to cross the simulation volume, the particles spontaneously formed a condensate, which immediately shaped itself into a spherical droplet, a Bose star, under the effect of gravity,” said one of the authors, Dmitry Levkov, Ph.D. in Physics, Senior Researcher at the Institute for Nuclear Research of the Russian Academy of Sciences.

    Dr. Levkov and his colleagues, Alexander Panin and Igor Tkachov from the Institute for Nuclear Physics of the Russian Academy of Sciences, concluded that Bose-Einstein condensate may form in the centres of halos of dwarf galaxies in a time smaller than the lifetime of the Universe. This means that Bose stars could populate them now.

    The authors were the first who saw the formation of the Bose-Einstein condensate from light dark matter in computer simulations. In previous numerical studies, the condensate was already present in the initial state, and Bose stars arose from it. According to one hypothesis, the Bose condensate could have formed in the early Universe long before the formation of galaxies or miniclusters, but reliable evidence for that is currently lacking. The authors demonstrated that the condensate is formed in the centres of small halos, and they plan to investigate condensation in the early Universe in further studies.

    The scientists pointed out that the Bose stars may produce Fast Radio Bursts that currently have no quantitative explanation. Light dark matter particles called “axions” interact with electromagnetic field very weakly and can decay into radiophotons. This effect is vanishingly small, but inside the Bose star it may be resonantly amplified like in a laser and could lead to giant radio bursts.

    “The next obvious step is to predict the number of the Bose stars in the Universe and calculate their mass in models with light dark matter,” concluded Dmitry Levkov.

    See the full article here .


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  • richardmitnick 1:19 pm on October 18, 2018 Permalink | Reply
    Tags: , At its summit the chip cooled its contents to -273.15 degrees Celsius, Bose-Einstein condensate, , MAIUS 1 is the first attempt to create a BEC in freefall, Matter-Wave Interferometry in Microgravity (MAIUS 1), ,   

    From Science Alert: “We Just Received The First Experiment Results From The Coldest Spot in Space” 


    From Science Alert

    18 OCT 2018

    (MAIUS project team/J. Matthias)

    The mission lasted for six minutes.

    In January last year, a rocket carrying a tiny chip packed with rubidium-87 atoms was launched more than 200 kilometres (124 miles) above the planet’s surface. The mission was brief, affording just six minutes of microgravity at its height.

    But in that time the tiny chip briefly held the record for being the coldest spot in space.

    On top of that, German researchers still managed to cram in more than 100 experiments. Their results are set to impact how we will one day study big things in the Universe.

    The Matter-Wave Interferometry in Microgravity (MAIUS 1) experiment launched from Kiruna in Sweden was the first of several missions aiming to study a special state of matter called a Bose-Einstein condensate (BEC) under microgravity conditions.

    Collections of atoms usually jiggle with energy in such a way that we can theoretically see them as individuals weaving through a crowd.

    Once that energy is taken away, they fall into a lull, for all purposes ending up with an identical set of characteristics, or quantum states. Rather than jump to their own beat, they become indistinguishable – a super particle with one identity.

    This condensate is incredibly useful for physicists wishing to probe the deeper nature of how particles behave.

    Forcing particles to be quiet typically entails holding them in an electromagnetic trap while carefully tuned lasers strike them with perfect timing, a little like hitting a person on a swing in such a way they slow down rather than speed up.

    Once the atoms are quiet, the trap can be turned off and the experiment can begin. Just be quick – you need to catch the atom cloud before it drops to the bottom of the container.

    Without gravity ruining the party, researchers would have more time to conduct more complicated experiments.

    MAIUS 1 is the first attempt to create a BEC in freefall.

    Usually, BECs need a room of equipment to cool atoms. So researchers from a number of German institutions had to first work together to miniaturise the setup.

    The end result was a small chip containing atoms of rubidium, which could be packed inside a sounding rocket – an unpiloted research vessel – and shot up to a height of 243 kilometres (150 miles).

    At its summit, the chip cooled its contents to -273.15 degrees Celsius (-459.67 degrees Fahrenheit).

    This is a degree colder than the Boomerang Nebula, which holds the honour of being the chilliest natural object we know of. So for a moment that cloud of rubidium atoms was literally the coldest known thing in space.

    For six minutes, the rocket experienced minimal gravity, before accelerating back to Earth. In total, the research team poked and prodded the cloud 110 different ways to gauge how gravity affects the trapping and cooling process, and how this cloud behaves in freefall.

    One particular set of experiments they ran could be immensely useful in the emerging study of gravitational waves.

    To detect the insanely tiny ripples in spacetime that echo from colliding monsters like black holes and neutron stars, astrophysicists currently split laser beams and recombine them. Discrepancies in their waves show as patterns of interference.

    The results from their tests show that BECs could provide another way to detect these waves, and potentially pick up different frequencies to current procedures.

    The researchers used a laser to split the cloud into two halves, and then allowed them to recombine. Since they should share the same quantum state – including its wave-like nature – any differences in the two when they merge could in principle indicate an external influence. Such as a change in their gravitational field.

    On Earth, there just wouldn’t be enough time to gather accurate readings. In freefall, the BEC could hang around long enough to potentially pick up gravitational waves, at least in theory.

    Several months ago, NASA announced their own world first – the creation of a BEC in orbit on board the International Space Station (ISS).

    While it wasn’t the first BEC to be created in a low g environment, the ISS’s Cold Atom Laboratory is set to break its own records for duration of ultracold experiments.

    And with more MAIUS missions on the horizon, all this ultra-cold research around the world is set to launch us into a new era of space exploration.

    This research was published in Nature.

    See the full article here .


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  • richardmitnick 2:00 pm on April 28, 2018 Permalink | Reply
    Tags: A DIY take on the early universe may reveal cosmic secrets, , , , Bose-Einstein condensate, COSMIC LOOP A rapidly expanding ring of ultracold atoms imitates the physics of the universe just after the Big Bang, ,   

    From ScienceNews: “A DIY take on the early universe may reveal cosmic secrets” 


    April 27, 2018
    Emily Conover

    A rapidly expanding ring of ultracold atoms mimics the physics just after the Big Bang.

    COSMIC LOOP A rapidly expanding ring of ultracold atoms imitates the physics of the universe just after the Big Bang. E. Edwards/JQI.

    A DIY universe mimics the physics of the infant cosmos, a team of physicists reports. The researchers hope to use their homemade cosmic analog to help explain the first instants of the universe’s 13.8-billion-year life.

    For their stand-in, the scientists created a Bose-Einstein condensate — a state of matter in which atoms are chilled until they all take on the same quantum state. Shaped into a tiny, rapidly expanding ring, the condensate grew from about 23 micrometers in diameter to about four times that size in just 15 milliseconds. The behavior of that widening condensate re-created some of the physics of inflation, a brief period just after the Big Bang during which the universe rapidly ballooned in size (SN Online: 12/11/13) before settling into a more moderate expansion rate.

    Alan Guth, Highland Park High School and M.I.T., who first proposed cosmic inflation

    HPHS Owls

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex MittelmannColdcreation

    Alan Guth’s notes:

    In physics, seemingly unrelated systems can have similarities under the hood. Scientists have previously used Bose-Einstein condensates to simulate other mysteries of the cosmos, such as black holes (SN: 11/15/14, p. 14). And the comparison between Bose-Einstein condensates and inflation is particularly apt: A hypothetical substance called the inflaton field is thought to drive the universe’s extreme expansion, and particles associated with that field, known as inflatons, all take on the same quantum state, just as atoms do in the condensate.

    Scientists still don’t fully understand how inflation progressed, “so it’s hard to know how close our system is to what really happened,” says experimental physicist Gretchen Campbell of the Joint Quantum Institute in College Park, Md. “But the hope is that our system can be a good test-bed” for studying various theories. Already, the scientists have spotted several effects in their system similar to those predicted in the baby cosmos, the team reports April 19 in Physical Review X.

    As the scientists expanded the ring, sound waves that were traveling through the condensate increased in wavelength. That change was similar to the way in which light became redshifted — stretched to longer wavelengths and redder colors — as the universe enlarged.

    Nice ring to it
    To mimic the physics of inflation in the early universe, scientists rapidly expanded a ring-shaped Bose-Einstein condensate, which decreased in density as it expanded over 15 milliseconds.
    S. Eckel et al/Physical Review X 2018

    Likewise, Campbell and colleagues saw a phenomenon akin to what’s known as Hubble friction, which shows up as a decrease in the density of particles in the early universe. In the experiment, this effect appeared in the guise of a weakening in the strength of the sound waves in the condensate.

    And inflation’s finale, an effect known as preheating that occurs at the end of the rapid expansion period, also had a look-alike in the simulated universe. In the cosmic picture, preheating occurs when inflatons transform into other types of particles. In the condensate, this showed up as sound waves converting from one type into another: waves that had been sloshing inward and outward broke up into waves going around the ring.

    However, the condensate wasn’t a perfect analog of the real universe: In particular, while our universe has three spatial dimensions, the expanding ring didn’t. Additionally, in the real universe, inflation proceeds on its own, but in this experiment, the researchers forced the ring to expand. Likewise, there were subtle differences between each of the effects observed and their cosmic counterparts.

    Despite the differences, the analog universe could be useful, says theoretical cosmologist Mustafa Amin of Rice University in Houston. “Who knows?” he says. “New phenomena might happen there that we haven’t thought about in the early universe.”

    Sometimes, when research crosses over between very different systems — such as Bose-Einstein condensates and the early universe — “sparks can fly,” Amin says.

    See the full article here .

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  • richardmitnick 9:28 am on May 22, 2017 Permalink | Reply
    Tags: , Bose-Einstein condensate, Bose–Einstein condensates simulate transformation of elusive magnetic monopoles, , Dirac monopole, ,   

    From COSMOS: “Bose–Einstein condensates simulate transformation of elusive magnetic monopoles” 

    Cosmos Magazine bloc


    22 May 2017
    Robyn Arianrhod

    For the first time physicists have experimentally simulated a long-predicted relationship between two kinds of magnetic monopole.

    Left: The quantum monopole. Right: the Dirac monopole. The different colors represent the direction of the internal magnetic state of the atoms and the brightness corresponds to particle density.
    Tuomas Ollikainen

    A team of physicists led by David Hall from Amherst College, USA, and Mikko Möttömen from Aalto University, Finland, has experimentally demonstrated the relationship between two different analogues of magnetic monopoles. The results, published in Physical Review X, provide the first demonstration of quantum monopole dynamics.

    The new research builds on a decade of earlier work, by Hall and Möttömen as well as by other teams, which focused on trying to synthesize monopole analogues in the first place.

    No image credit. http://io9.gizmodo.com/5620547/ask-a-physicist-what-ever-happened-to-magnetic-monopoles

    Real magnetic monopoles – the magnetic counterparts of electrons and protons, the fundamental negative and positive electric charges that make up the atoms in our universe – have yet to be observed. Magnets always have two poles, north and south, and so far no amount of metaphorical slicing and dicing has been able to isolate separate north and south poles: rather, cutting a magnet in two simply produces two magnets, each with a north and a south pole.

    This asymmetry between electricity and magnetism has long puzzled physicists. It also spoils the beauty of James Clerk Maxwell’s celebrated 1864 equations of electromagnetism. But there is no theoretical reason not to put the symmetry back into Maxwell’s equations, by adding in magnetic “charges” (monopoles) analogous to the electric charges, and in 1931, pioneering British quantum physicist Paul Dirac showed how to reinterpret the relevant quantum mechanical equations in this light. He found that the force between two opposite magnetic monopoles would be nearly 5000 times as strong as the force between an electron and a proton. No wonder, he mused, that no-one has yet been able to separate magnetic poles. Which is why physicists have recently turned to simulating monopoles.

    “My feeling is that some of the details associated with the Dirac monopole are not fully appreciated by the wider physics community,” says Hall. Experiments can help physicists to better understand this elegant theory, and ultimately, perhaps, point to ways of discovering whether or not real monopoles exist. But there are also potential practical benefits.

    Back in 2009, Jonathan Morris was part of a team from Berlin’s Helmholtz Centre that found magnetic monopole analogues in strange structures known as “spin-ice”, and he believes we could be in for a slew of new technologies using simulated monopoles. But first, he cautions, “we must get to the bottom of how monopoles behave”.

    And that means spending many hours in the lab – hours that often involve “a lot of unglamorous day-to-day problem-solving,” as Hall puts it. Working out how to remove “noise” from everyday magnetic fields created by overhead power lines, computers, and the Earth itself was a real headache in the early research, Hall laments; in these latest delicate experiments, even something as simple as a pair of steel scissors had to be banned from the lab.

    To isolate and study their monopole analogues, Hall, Möttönen and their colleagues used a cloud of extremely cold rubidium atoms.

    (This is known as a Bose–Einstein condensate, or BEC for short.

    Condensed matter physics
    Phase diagram of a second order quantum phase transition
    Author DG85

    Theoretically predicted in 1924, the first BEC was not actually made until 1995; its creators received the 2001 Nobel Prize for physics. Following in their footsteps, Hall and his undergraduate students at Amherst made their own atomic refrigerator in 2002, and it is still going strong.)

    A BEC acts as a sort of magnifying glass, because the cloud of atoms, cooled to almost absolute zero, behaves in just the same way as if it were a single quantum particle. This “magnification” makes it possible to observe and photograph the way a BEC “electron” behaves in a simulated magnetic monopolar field, or the way a “monopole” forms. It’s about making a model of something that is not really electromagnetic, but which behaves just the way quantum mechanics says that an electron or a magnetic monopole should behave.

    By contrast, a number of international teams have found that “spin-ice” does seem to contain a lattice of monopoles that are really magnetic, although they, too, are analogues of the free-moving real monopoles that would parallel electrons and protons. Each experimental analogue adds to physicists’ knowledge, and in the latest research, Hall, Möttönen and their colleagues have taken their model to a new level by demonstrating the relationship between analogues of Dirac monopoles and “isolated” or “topological” monopoles.

    Predicted by t’Hooft and Polyakov in 1974, an “isolated” monopole is mathematically different from Dirac’s version, but theory says that at a suitable distance it effectively becomes a Dirac monopole.

    Hall’s team began by allowing a simulated “isolated” monopole to evolve in time.

    “This is where noise can really wreak havoc,” says Hall. “The problem is compounded because to study the process over time, we don’t simply take a movie of a sample, one frame after the other, but we have to take each frame with a different sample, waiting a little longer after the creation [of the isolated monopole analogue] to take each successive frame. It’s as if you create the movie set, take a picture, and then the set is destroyed. Then you recreate the set, wait a little longer, take the picture, and it is destroyed again. It’s annoying enough to have to recreate the set every time you need another frame of the movie. Now imagine that every time the director calls ‘Action!’ the scene props are being blown randomly all over the place because it is violently windy.” The winds are the “noise” that needs to be filtered out before the data can be interpreted.

    But these laborious experiments have hit paydirt: for the first time, physicists have observed the spontaneous creation of a Dirac monopole analogue from the decay of a simulated t’Hooft–Polyakov monopole.

    Artistic view of the decay of a quantum-mechanical monopole into a Dirac monopole. Credit: Heikka Valja. phys.org

    “I was jumping in the air the first time I saw it,” says Möttönen. As for Hall, “I knew to expect this from the theory, but to see it in the data – that was pretty wild. It felt like watching a sculpture take form from a block of marble.”

    See the full article here .

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  • richardmitnick 6:58 pm on March 6, 2017 Permalink | Reply
    Tags: Bose-Einstein condensate, Cold Atom Laboratory (CAL), , NASA Wants to Create the Coolest Spot in the Universe   

    From JPL-Caltech: “NASA Wants to Create the Coolest Spot in the Universe” 

    NASA JPL Banner


    March 6, 2017
    Andrew Good
    Jet Propulsion Laboratory, Pasadena, Calif.

    Artist’s concept of an atom chip for use by NASA’s Cold Atom Laboratory (CAL) aboard the International Space Station. CAL will use lasers to cool atoms to ultracold temperatures. Image Credit: NASA

    This summer, an ice chest-sized box will fly to the International Space Station, where it will create the coolest spot in the universe.

    Inside that box, lasers, a vacuum chamber and an electromagnetic “knife” will be used to cancel out the energy of gas particles, slowing them until they’re almost motionless. This suite of instruments is called the Cold Atom Laboratory (CAL), and was developed by NASA’s Jet Propulsion Laboratory in Pasadena, California. CAL is in the final stages of assembly at JPL, ahead of a ride to space this August on SpaceX CRS-12.

    Its instruments are designed to freeze gas atoms to a mere billionth of a degree above absolute zero. That’s more than 100 million times colder than the depths of space.

    “Studying these hyper-cold atoms could reshape our understanding of matter and the fundamental nature of gravity,” said CAL Project Scientist Robert Thompson of JPL. “The experiments we’ll do with the Cold Atom Lab will give us insight into gravity and dark energy — some of the most pervasive forces in the universe.”

    When atoms are cooled to extreme temperatures, as they will be inside of CAL, they can form a distinct state of matter known as a Bose-Einstein condensate. In this state, familiar rules of physics recede and quantum physics begins to take over. Matter can be observed behaving less like particles and more like waves. Rows of atoms move in concert with one another as if they were riding a moving fabric. These mysterious waveforms have never been seen at temperatures as low as what CAL will achieve.

    NASA has never before created or observed Bose-Einstein condensates in space. On Earth, the pull of gravity causes atoms to continually settle towards the ground, meaning they’re typically only observable for fractions of a second.

    But on the International Space Station, ultra-cold atoms can hold their wave-like forms longer while in freefall. That offers scientists a longer window to understand physics at its most basic level. Thompson estimated that CAL will allow Bose-Einstein condensates to be observable for up to five to 10 seconds; future development of the technologies used on CAL could allow them to last for hundreds of seconds.

    Bose-Einstein condensates are a “superfluid” — a kind of fluid with zero viscosity, where atoms move without friction as if they were all one, solid substance.

    “If you had superfluid water and spun it around in a glass, it would spin forever,” said Anita Sengupta of JPL, Cold Atom Lab project manager. “There’s no viscosity to slow it down and dissipate the kinetic energy. If we can better understand the physics of superfluids, we can possibly learn to use those for more efficient transfer of energy.”

    Five scientific teams plan to conduct experiments using the Cold Atom Lab. Among them is Eric Cornell of the University of Colorado, Boulder and the National Institute for Standards and Technology. Cornell is one of the Nobel Prize winners who first created Bose-Einstein condensates in a lab setting in 1995.

    The results of these experiments could potentially lead to a number of improved technologies, including sensors, quantum computers and atomic clocks used in spacecraft navigation.

    Especially exciting are applications related to dark energy detection, said Kamal Oudrhiri of JPL, the CAL deputy project manager. He noted that current models of cosmology divide the universe into roughly 27 percent dark matter, 68 percent dark energy and about 5 percent ordinary matter.

    “This means that even with all of our current technologies, we are still blind to 95 percent of the universe,” Oudrhiri said. “Like a new lens in Galileo’s first telescope, the ultra-sensitive cold atoms in the Cold Atom Lab have the potential to unlock many mysteries beyond the frontiers of known physics.”

    The Cold Atom Lab is currently undergoing a testing phase that will prepare it prior to delivery to Cape Canaveral, Florida.

    “The tests we do over the next months on the ground are critical to ensure we can operate and tune it remotely while it’s in space, and ultimately learn from this rich atomic physics system for years to come,” said Dave Aveline, the test-bed lead at JPL.

    JPL is developing the Cold Atom Laboratory, sponsored by the International Space Station Program at NASA’s Johnson Space Center in Houston.

    The Space Life and Physical Sciences Division of NASA’s Human Exploration and Operations Mission Directorate at NASA Headquarters in Washington manages the Fundamental Physics Program.

    For more information about the Cold Atom Lab, visit:


    The Cold Atom Lab will be the topic of two free lectures in March, one of which will be streamed live at:


    Details about the lecture are at:


    See the full article here .

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  • richardmitnick 10:58 pm on March 3, 2017 Permalink | Reply
    Tags: , Bose-Einstein condensate, , ,   

    From MIT: “MIT researchers create new form of matter” 

    MIT News

    MIT Widget

    MIT Physics

    March 2, 2017
    Julia C. Keller

    The Ketterle group at MIT’s Killian court. Pictured from left to right: Furkan Çağrı Top, Junru Li, Sean Burchesky, Alan O. Jamison, Wolfgang Ketterle, Boris Shteynas, Wujie Huang, and Jeongwon Lee.
    Photo courtesy of the researchers.

    This image shows the equipment used by the Ketterle group to create a supersolid. Photo courtesy of the researchers.

    Supersolid is crystalline and superfluid at the same time.

    MIT physicists have created a new form of matter, a supersolid, which combines the properties of solids with those of superfluids.

    By using lasers to manipulate a superfluid gas known as a Bose-Einstein condensate, the team was able to coax the condensate into a quantum phase of matter that has a rigid structure — like a solid — and can flow without viscosity — a key characteristic of a superfluid. Studies into this apparently contradictory phase of matter could yield deeper insights into superfluids and superconductors, which are important for improvements in technologies such as superconducting magnets and sensors, as well as efficient energy transport. The researchers report their results this week in the journal Nature.

    “It is counterintuitive to have a material which combines superfluidity and solidity,” says team leader Wolfgang Ketterle, the John D. MacArthur Professor of Physics at MIT. “If your coffee was superfluid and you stirred it, it would continue to spin around forever.”

    Physicists had predicted the possibility of supersolids but had not observed them in the lab. They theorized that solid helium could become superfluid if helium atoms could move around in a solid crystal of helium, effectively becoming a supersolid. However, the experimental proof remained elusive.

    The team used a combination of laser cooling and evaporative cooling methods, originally co-developed by Ketterle, to cool atoms of sodium to nanokelvin temperatures. Atoms of sodium are known as bosons, for their even number of nucleons and electrons. When cooled to near absolute zero, bosons form a superfluid state of dilute gas, called a Bose-Einstein condensate, or BEC.

    Ketterle co-discovered BECs — a discovery for which he was recognized with the 2001 Nobel Prize in physics.

    “The challenge was now to add something to the BEC to make sure it developed a shape or form beyond the shape of the ‘atom trap,’ which is the defining characteristic of a solid,” explains Ketterle.

    Flipping the spin, finding the stripes

    To create the supersolid state, the team manipulated the motion of the atoms of the BEC using laser beams, introducing “spin-orbit coupling.”

    In their ultrahigh-vacuum chamber, the team used an initial set of lasers to convert half of the condensate’s atoms to a different quantum state, or spin, essentially creating a mixture of two Bose-Einstein condensates. Additional laser beams then transferred atoms between the two condensates, called a “spin flip.”

    “These extra lasers gave the ‘spin-flipped’ atoms an extra kick to realize the spin-orbit coupling,” Ketterle says.

    Physicists had predicted that a spin-orbit coupled Bose-Einstein condensate would be a supersolid due to a spontaneous “density modulation.” Like a crystalline solid, the density of a supersolid is no longer constant and instead has a ripple or wave-like pattern called the “stripe phase.”

    “The hardest part was to observe this density modulation,” says Junru Li, an MIT graduate student who worked on the discovery. This observation was accomplished with another laser, the beam of which was diffracted by the density modulation. “The recipe for the supersolid is really simple,” Li adds, “but it was a big challenge to precisely align all the laser beams and to get everything stable to observe the stripe phase.”

    Mapping out what is possible in nature

    Currently, the supersolid only exists at extremely low temperatures under ultrahigh-vacuum conditions. Going forward, the team plans to carry out further experiments on supersolids and spin-orbit coupling, characterizing and understanding the properties of the new form of matter they created.

    “With our cold atoms, we are mapping out what is possible in nature,” explains Ketterle. “Now that we have experimentally proven that the theories predicting supersolids are correct, we hope to inspire further research, possibly with unanticipated results.”

    Several research groups were working on realizing the first supersolid. In the same issue of Nature, a group in Switzerland reported an alternative way of turning a Bose-Einstein condensate into a supersolid with the help of mirrors, which collected laser light scattering by the atoms. “The simultaneous realization by two groups shows how big the interest is in this new form of matter,” says Ketterle.

    Ketterle’s team members include graduate students Junru Li, Boris Shteynas, Furkan Çağrı Top, and Wujie Huang; undergraduate Sean Burchesky; and postdocs Jeongwon Lee and Alan O. Jamison, all of whom are associates at MIT’s Research Laboratory of Electronics.

    This research was funded by the National Science Foundation, the Air Force Office for Scientific Research, and the Army Research Office.

    See the full article here .

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