quantum_mechanics (15)

Greener Solar Cells...

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Scanning electron microscope image of electrodes infiltrated with quantum dots (left) and the corresponding distributions of copper, indium, zinc, and selenium across the film thickness. Courtesy: LANL
 
 

Topics: Green Tech, Nanotechnology, Quantum Mechanics, Solar Cells

Semiconducting nanocrystals called colloidal quantum dots (CQDs) are ideal for applications such as large-panel displays and photovoltaic cells thanks to their high efficiency and colour purity. Their main drawback is their toxicity, since they have traditionally been made from cadmium or other heavy metals, such as lead. Researchers at the Los Alamos National Laboratory in the US have now engineered cadmium-free QD solar cells that reach efficiencies on par with those of their environmentally-unfriendly counterparts. The key to the new devices’ high performance is their tolerance to defects, they say.

CQDs can be synthesized in solution, which means that films of these nanocrystals can be deposited quickly and easily on a range of flexible or rigid substrates – just like paint or ink. Such semiconducting nanocrystals are ideal for making highly-efficient inorganic solar cells that emit light via a process known as radiative recombination. Here, an electron in the valency energy band in the QD absorbs a photon and moves to the conduction band, leaving behind an electron vacancy, or hole. The excited electron and hole then recombine, releasing a photon.

The advantage of using CQDs as photovoltaic materials in solar cells is that they absorb light over a broad spectrum of solar radiation wavelengths. This is because the band gap of a CQD can be tuned over a large energy range by simply changing the size of the nanocrystals. Such a size-tuneable property has allowed the efficiencies of these QDs to rapidly approach those of traditional thin-film photovoltaics, such as PbS, CdTe and Pb-halide perovskite QDs.

Quantum dot solar cells get greener, Isabelle Dumé, Physics World

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Axions...

 

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Image Source: Axion particle spotted in solid-state crystal, Max Planck Society, Phys.org

 

 

Topics: Cosmology, Dark Matter, Particle Physics, Quantum Mechanics, Standard Model

A team of physicists has made what might be the first-ever detection of an axion.

Axions are unconfirmed, hypothetical ultralight particles from beyond the Standard Model of particle physics, which describes the behavior of subatomic particles. Theoretical physicists first proposed the existence of axions in the 1970s in order to resolve problems in the math governing the strong force, which binds particles called quarks together. But axions have since become a popular explanation for dark matter, the mysterious substance that makes up 85% of the mass of the universe, yet emits no light.

If confirmed, it’s not yet certain whether these axions would, in fact, fix the asymmetries in the strong force. And they wouldn’t explain most of the missing mass in the universe, said Kai Martens, a physicist at the University of Tokyo who worked on the experiment. These axions, which appear to be streaming out of the sun, don’t act like the “cold dark matter” that physicists believe fills halos around galaxies. And they would be particles newly brought into being inside the sun, while the bulk of the cold dark matter out there appears to have existed unchanged for billions of years since the early universe.*

Still, it sure seems like there was a signal. It turned up in a dark underground tank of 3.5 tons (3.2 metric tons) of liquid xenon—the XENON1T experiment based at the Gran Sasso National Laboratory in Italy. At least two other physical effects could explain the XENON1T data. However, the researchers tested several theories and found that axions streaming out of our sun were the likeliest explanation for their results.

Physicists who weren’t involved in the experiment have not reviewed the data as of the announcement at 10 a.m. ET today (June 17). Reporters were briefed on the finding before the announcement, but data and paper on the find were not made available.

Live Science shared the XENON collaboration’s press release with two axion experts.

Physicists Announce Potential Dark Matter Breakthrough, Rafi Letzter, Live Science/Scientific American

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Majorana qubits...

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Image Source: Link below

 

Topics: History, Modern Physics, Quantum Computer, Quantum Mechanics

Soon after Enrico Fermi became a professor of physics at Italy’s University of Rome in 1927, Ettore Majorana joined his research group. Majorana’s colleagues described him as humble because he considered some of his work unexceptional. For example, Majorana correctly predicted in 1932 the existence of the neutron, which he dubbed a neutral proton, based on an atomic-structure experiment by Irène Joliot-Curie and Frédéric Joliot-Curie. Despite Fermi’s urging, Majorana didn’t write a paper. Later that year James Chadwick experimentally confirmed the neutron’s existence and was awarded the 1935 Nobel Prize in Physics for the discovery.

Nevertheless, Fermi thought highly of Majorana, as is captured in the following quote: “There are various categories of scientists, people of a secondary or tertiary standing, who do their best but do not go very far. There are also those of high standing, who come to discoveries of great importance, fundamental for the development of science. But then there are geniuses like Galileo and Newton. Well, Ettore was one of them.” Majorana only wrote nine papers, and the last one, about the now-eponymous fermions, was published in 1937 at Fermi’s insistence. A few months later, Majorana took a night boat to Palermo and was never seen again.1

In that final article, Majorana presented an alternative representation of the relativistic Dirac equation in terms of real wavefunctions. The representation has profound consequences because a real wavefunction describes particles that are their own antiparticles, unlike electrons and positrons. Since particles and antiparticles have opposite charges, fermions in his new representation must have zero charge. Majorana postulated that the neutrino could be one of those exotic fermions.

Although physicists have observed neutrinos for more than 60 years, whether Majorana’s hypothesis is true remains unclear. For example, the discovery of neutrino oscillations, which earned Takaaki Kajita and Arthur McDonald the 2015 Nobel Prize in Physics, demonstrates that neutrinos have mass. But the standard model requires that neutrinos be massless, so various possibilities have been hypothesized to explain the discrepancy. One answer could come from massive neutrinos that do not interact through the weak nuclear force. Such sterile neutrinos could be the particles that Majorana predicted. Whereas conclusive evidence for the existence of Majorana neutrinos remains elusive, researchers are now using Majorana’s idea for other applications, including exotic excitations in superconductors.

Majorana qubits for topological quantum computing, Physics Today

Ramón Aguado is a senior researcher at the Spanish National Research Council (CSIC) in Madrid.

Leo Kouwenhoven is a researcher at the Microsoft Quantum Lab Delft and a professor of applied physics at Delft University of Technology in the Netherlands.

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Quantum Time...

 

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"Weird Time Tunnel." Image Source Below.

 

Topics: Quantum Computer, Quantum Mechanics, Thermodynamics

It's easy to take time's arrow for granted - but the gears of physics actually work just as smoothly in reverse. Maybe that time machine is possible after all?

An experiment from 2019 shows just how much wiggle room we can expect when it comes to distinguishing the past from the future, at least on a quantum scale. It might not allow us to relive the 1960s, but it could help us better understand why not.

Researchers from Russia and the US teamed up to find a way to break, or at least bend, one of physics' most fundamental laws of energy.

The second law of thermodynamics is less a hard rule and more of a guiding principle for the Universe. It says hot things get colder over time as energy transforms and spreads out from areas where it's most intense.

It's a principle that explains why your coffee won't stay hot in a cold room, why it's easier to scramble an egg than unscramble it, and why nobody will ever let you patent a perpetual motion machine.

Virtually every other rule in physics can be flipped and still make sense. For example, you could zoom in on a game of pool, and a single collision between any two balls won't look weird if you happened to see it in reverse.

On the other hand, if you watched balls roll out of pockets and reform the starting pyramid, it would be a sobering experience. That's the second law at work for you.

Electrons aren't like tiny billiard balls, they're more akin to information that occupies a space. Their details are defined by something called the Schrödinger equation, which represents the possibilities of an electron's characteristics as a wave of chance.

Physicists Have Reversed Time on The Smallest Scale Using a Quantum Computer
Mike McCrae, Science Alert

 

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Kondo Effect...

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Daniel Mazzone led the project to explore the mechanism that causes samarium sulphide to expand dramatically when cooled. Credit: Brookhaven National Laboratory

 

Topics: Materials Science, Quantum Mechanics, Research, Thermodynamics

Most metals expand when heated and contract when cooled. A few metals, however, do the opposite, exhibiting what’s known as negative thermal expansion (NTE). A team of researchers led by Ignace Jarrige and Daniel Mazzone of Brookhaven National Laboratory in the US has now found that in one such metal, yttrium-doped samarium sulphide (SmS), NTE is linked to a quantum many-body phenomenon called the Kondo effect. The work could make it possible to develop alloys in which positive and negative expansion cancel each other out, producing a composite material with a net-zero thermal expansion – a highly desirable trait for applications in aerospace and other areas of hi-tech manufacturing.

Even within the family of NTE materials, yttrium-doped SmS is an outlier, gradually expanding by up to 3% when cooled over a few hundred degrees. To better understand the mechanisms behind this “giant” NTE behavior, Mazzone and Jarrige employed X-ray diffraction and spectroscopy to investigate the material’s electronic properties.

The researchers carried out the first experiments at the Pair Distribution Function (PDF) beamline at Brookhaven’s National Synchrotron Light Source (II) (NSLS-II). They placed their SmS sample inside a liquid-helium cooled cryostat in the beam of the synchrotron X-rays and measured how the X-rays scattered off the electron clouds around the atomic ions. By tracking how these X-rays scatter, they identified the locations of the atoms in the crystal structure and the spacings between them.

“Our results show that, as the temperature drops, the atoms of this material move farther apart, causing the entire material to expand by up to 3% in volume,” says Milinda Abeykoon, the lead scientist on the PDF beamline.

Kondo effect induces giant negative thermal expansion, Belle Dumé, Physics World

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WSMs...

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Figure 1.
Spin–orbit coupling can open a bulk bandgap in materials with inverted valence and conduction bands. That gap is complete in a topological insulator, but in a Weyl semimetal, the bands still touch at certain points. Both phases also host surface states not shown here. (Adapted from ref. 4, B. Yan and C. Felser.)

 

Topics: Modern Physics, Particle Physics, Quantum Mechanics


When Paul Dirac introduced his famous equation for relativistic fermions in 1928, he aimed to describe one well-known particle: the electron. Shortly thereafter, Hermann Weyl observed that the equation has a special solution when the mass is set to zero. The so-called Weyl fermions embodied by that solution would be charged, like electrons, but being massless, they would travel faster and with less energy dissipation. The particles would also be chiral, like neutrinos, with each one’s handedness depending on whether its spin is aligned or antialigned with its momentum. Those features make Weyl fermions appealing candidates for use in electronic and spintronic devices.

No such elementary particle has yet been found. However, in 2015 three groups of researchers identified the first Weyl semimetal (WSM), tantalum arsenide, which hosts quasiparticles—collective excitations of electrons—with the properties of Weyl fermions.1 A WSM must have a broken symmetry, and in TaAs, it’s inversion symmetry. Researchers, however, have continued searching for materials, particularly ferromagnetic materials, that instead rely on broken time-reversal symmetry. Tying a WSM crystal’s properties to magnetism, which can be adjusted using temperature changes or external fields, makes them potentially tunable.

Three new papers provide experimental evidence for magnetic WSMs. Yulin Chen’s team at Oxford University and Haim Beidenkopf’s team at the Weizmann Institute of Science, together with collaborators,2 presented studies of Co3Sn2S2, and Zahid Hasan’s group at Princeton University3 looked at Co2MnGa. The works identify important features in the electronic structures of both materials’ bulk and surface states.

 

Magnetic semimetals host massless quasiparticles, Christine Middleton, Physics Today

#P4TC: Weyl Fermions...July 27, 2015

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Structured Light...

 
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This image shows the creation of hybrid entangled photons by combining polarization with a "twisted" pattern that carries orbital angular momentum. Credit: Forbes and Nape

 

Topics: Electrical Engineering, Electromagnetic Radiation, Quantum Computing, Quantum Electrodynamics, Quantum Mechanics


Structured light is a fancy way to describe patterns or pictures of light, but deservedly so as it promises future communications that will be both faster and more secure.

Quantum mechanics has come a long way during the past 100 years but still has a long way to go. In AVS Quantum Science researchers from the University of Witwatersrand in South Africa review the progress being made in using structured light in quantum protocols to create a larger encoding alphabet, stronger security and better resistance to noise.

"What we really want is to do quantum mechanics with patterns of light," said author Andrew Forbes. "By this, we mean that light comes in a variety of patterns that can be made unique—like our faces."

Since patterns of light can be distinguished from each other, they can be used as a form of alphabet. "The cool thing is that there are, in principle at least, an infinite set of patterns, so an infinite alphabet is available," he said.

Traditionally, quantum protocols have been implemented with the polarization of light, which has only two values—a two-level system with a maximum information capacity per photon of just 1 bit. But by using patterns of light as the alphabet, the information capacity is much higher. Also, its security is stronger, and the robustness to noise (such as background light fluctuations) is improved.

"Patterns of light are a route to what we term high-dimensional states," Forbes said. "They're high dimensional, because many patterns are involved in the quantum process. Unfortunately, the toolkit to manage these patterns is still underdeveloped and requires a lot of work."
 

Structured light promises path to faster, more secure communications
American Institute of Physics, Phys.org

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Quantum Google...

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Linear computation: montage of a photo of the chip containing the trapped ions and an image of the ions in a 1D array (Courtesy: Christopher Monroe) Physicsworld.com

 

Topics: Internet, Quantum Computer, Quantum Computing, Quantum Mechanics


Google said it has achieved a breakthrough in quantum computing research, saying an experimental quantum processor has completed a calculation in just a few minutes that would take a traditional supercomputer thousands of years.

The findings, published Wednesday in the scientific journal Nature, show that "quantum speedup is achievable in a real-world system and is not precluded by any hidden physical laws," the researchers wrote.

Quantum computing is a nascent and somewhat bewildering technology for vastly sped-up information processing. Quantum computers are still a long way from having a practical application but might one day revolutionize tasks that would take existing computers years, including the hunt for new drugs and optimizing city and transportation planning.

The technique relies on quantum bits, or qubits, which can register data values of zero and one—the language of modern computing—simultaneously. Big tech companies including Google, Microsoft, IBM and Intel are avidly pursuing the technology.

"Quantum things can be in multiple places at the same time," said Chris Monroe, a University of Maryland physicist who is also the founder of quantum startup IonQ. "The rules are very simple, they're just confounding."

 

Google touts quantum computing milestone
Rachel Lerman

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Quantum Sound...

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Credit: Getty Images

 

Topics: Modern Physics, Phonons, Quantum Mechanics, Theoretical Physics


Researchers have gained control of the elusive “particle” of sound, the phonon. Although phonons—the smallest units of the vibrational energy that makes up sound waves—are not matter, they can be considered particles the way photons are particles of light. Photons commonly store information in prototype quantum computers, which aim to harness quantum effects to achieve unprecedented processing power. Using sound instead may have advantages, although it would require manipulating phonons on very fine scales.

Until recently, scientists lacked this ability; just detecting an individual phonon destroyed it. Early methods involved converting phonons to electricity in quantum circuits called superconducting qubits. These circuits accept energy in specific amounts; if a phonon’s energy matches, the circuit can absorb it—destroying the phonon but giving an energy reading of its presence.

In a new study, scientists at JILA (a collaboration between the National Institute of Standards and Technology and the University of Colorado Boulder) tuned the energy units of their superconducting qubit so phonons would not be destroyed. Instead the phonons sped up the current in the circuit, thanks to a special material that created an electric field in response to vibrations. Experimenters could then detect how much change in current each phonon caused.

“There’s been a lot of recent and impressive successes using superconducting qubits to control the quantum states of light. And we were curious—what can you do with sound that you can’t with light?” says Lucas Sletten of U.C. Boulder, lead author of the study published in June in Physical Review X. One difference is speed: sound travels much slower than light. Sletten and his colleagues took advantage of this to coordinate circuit-phonon interactions that sped up the current. They trapped phonons of particular wavelengths (called modes) between two acoustic “mirrors,” which reflect sound, and the relatively long time sound takes to make a round trip allowed the precise coordination. The mirrors were a hair’s width apart—similar control of light would require mirrors separated by about 12 meters.

 

Trapping the Tiniest Sound, Leila Sloman, Scientific American

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Dunamis Novem...

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Image source: "Dunamis Novem" link below

Topics: NIST, Quantum Mechanics, Research, STEAM


Quantum physics drives much of the research at the National Institute of Standards and Technology (NIST). Explaining this research is a challenge, because quantum physics—nature's rules for the smallest particles of matter and light—inspires words like weird, curious, and counter-intuitive. The quantum world is strange and invisible in the context of everyday life. And yet, quantum physics can be explained and at least partially demonstrated visually.

NIST physicist Ray Simmonds recently collaborated with MFA graduate candidate Sam Mitchell of the University of California, San Diego (UCSD), to create a dance piece based on the laws of quantum physics. The piece, Dunamis Novem (Latin for "the chance happening of nine things"),* premiered at The La Jolla Playhouse Forum Theatre in January, as a part of Mitchell's thesis work.

The project has practical benefits such as education, Simmonds says.

"While quantum mechanics is a well-established theory, proven true overwhelmingly by experiments, it is still confounding to most people, even those in science," Simmonds and Mitchell noted in describing their work.

“Quantum Statistics: Affects on Human Dancers and the Observer”

Abstract

The Arts and Sciences may seem to be immiscible fields of study, even at odds with each other. In Leonardo Da Vinci’s time these two fields were not polarized, in fact, they coexisted naturally. Despite the appearance of being far distant cousins, both artists and scientists share a creative gene, a passion for their work, and a brave curiosity that pushes them past current boundaries to explore the unknown. In this lecture, we will present some recent examples of those mixing these two worlds and our own attempts to do so with Dance Theater and Quantum Physics. While quantum mechanics is a well-established theory, proven true overwhelmingly by experiments, it is still confounding to most people, even those in science. At its heart, it describes nature in terms of possible realities with probable outcomes, with almost no predictable certainty. Experts still struggle to interpret its philosophical consequences and the notion that there may be no “objective reality”. Even Albert Einstein, one of its co-creators, disapproved of its bizarre properties, saying that “God does not play dice with the universe”. In the creation of this work, “Dunamis Novem”, we have taken some of the probabilistic rules that govern quantum systems and integrated them into a creative process. The results are then born from an artistic aesthetic and an algorithmic code that produces dynamics that embody in some way randomness, concepts of “quantum entanglement”, and the effects of observation or “measurement”. Our work shows that “Science” can inspire and direct new forms of “Art”, and we hope that the liminal world of “Art” can be an effective medium to transmit the sometimes counterintuitive results of empirical “Science” to a broader audience, also generating a dialogue between the two. We will describe the scientific concepts that currently inspire us, the process by which we convert quantum principles into movements, and the challenges of distilling this into a theatrical setting.

 

What is Quantum Physics? Dancers Explain, NIST
Sam Mitchel Dance: Dunamis Novem

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Entanglement...

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Physicists take first-ever photo of quantum entanglement.
Credit: University of Glasgow/CC by 4.0

 

Topics: Einstein, Entanglement, Laser, Quantum Mechanics


Scientists just captured the first-ever photo of the phenomenon dubbed "spooky action at a distance" by Albert Einstein. That phenomenon, called quantum entanglement, describes a situation where particles can remain connected such that the physical properties of one will affect the other, no matter the distance (even miles) between them.

Einstein hated the idea, since it violated classical descriptions of the world. So he proposed one way that entanglement could coexist with classical physics — if there existed an unknown, "hidden" variable that acted as a messenger between the pair of entangled particles, keeping their fates entwined. [18 Times Quantum Particles Blew Our Minds in 2018]

There was just one problem: There was no way to test whether Einstein's view — or the stranger alternative, in which particles "communicate" faster than the speed of light and particles have no objective state until they are observed — was true. Finally, in the 1960s, physicist Sir John Bell came up with a test that disproves the existence of these hidden variables — which would mean that the quantum world is extremely weird.

This is "the pivotal test of quantum entanglement," said senior author Miles Padgett, who holds the Kelvin Chair of Natural Philosophy and is a professor of physics and astronomy at the University of Glasgow in Scotland. Though people have been using quantum entanglement and Bell's inequalities in applications such as quantum computing and cryptography, "this is the first time anyone has used a camera to confirm [it]."

To take the photo, Padgett and his team first had to entangle photons, or light particles, using a tried-and-true method. They hit a crystal with an ultraviolet (UV) laser, and some of those photons from the laser broke apart into two photons. "Due to conservation of both energy and momentum, each resulting pair [of] photons are entangled," Padgett said.

 

'Spooky' Quantum Entanglement Finally Captured in Stunning Photo
Yasemin Saplakoglu, Live Science

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Ionic Clock...

Physics World: A brief history of timekeeping


Topics: Atomic Physics, Laser, NIST, Quantum Mechanics, Research


By confining single ions of aluminum and magnesium in an electric trap, cooling them to near absolute zero and probing them with laser beams, physicists at the National Institute of Standards and Technology (NIST) in Boulder, Colorado have built what is in effect the world’s most accurate clock. Having fractionally improved on the performance of another clock at NIST, the researchers have shown that their device would neither gain nor lose a second in 33 billion years (if it could run for that long). Such accurate timekeeping, they say, could boost geodesy and lead to new insights in fundamental physics.

The clocks that currently underpin atomic time rely on precisely measuring the frequency of microwaves emitted during a specific transition in cesium atoms. But such devices are limited by the relatively low frequency of that radiation. To keep time even more accurately, and eventually introduce a new definition of the second, physicists are developing clocks based on higher-frequency optical transitions.

The latest work at NIST features what is known as a quantum-logic clock. Built by Samuel Brewer and colleagues, it uses a positive ion of aluminum-27 as its timekeeper. When exposed to ultraviolet laser light at wavelength 267 nm, the ion undergoes a transition with a very narrow line width – making its frequency very well defined. What is more, that transition is largely immune to sources of external noise – such as blackbody radiation – that in other types of optical clock shift the frequency away from its true value.

A magnesium-25 ion is used to cool the aluminum down to the very low temperatures needed to minimize thermal noise. Cooling involves the absorption of photons at another specific frequency, but practical limitations mean that this cannot be done using the aluminum itself. This is because the required frequency in is too high for any practical laser. By entangling the two ions, the magnesium cools the aluminum via Coulomb interactions. This process also allows the quantum state of the aluminum ion to be read-out following exposure to the clock laser.

 

Entangled aluminum ion is world’s best timekeeper, Edwin Cartlidge, Physics World

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Left, schematics of the apparatus (positron beam, collimators, SiN gratings and emulsion detector. A HpGe detector is used as beam monitor). Right, single-particle interference visibility as a function of the positron energy is in agreement with quantum mechanics (blue) and disagrees with classical physics (orange dashed). Courtesy: Politecnico di Milano

 

Topics: Antimatter, High Energy Physics, Particle Physics, Quantum Mechanics


Researchers in Italy and Switzerland have performed the first ever double-slit-like experiment on antimatter using a Talbot-Lau interferometer and a positron beam.

The classic double-slit experiment confirmed that light and matter have the characteristics of both waves and particles, a duality that was first put forward by de Broglie in 1923. This superposition principle is one of the main postulates of quantum mechanics and researchers have since been able to diffract and interfere matter waves of objects of increasing complexity – from electrons to neutrons and molecules.

The QUPLAS (QUantum Interferometry and Gravitation with Positrons and LAsers) collaboration, which includes researchers from the Politecnico di Milano L-NESS in Como, the Milan unit of the Istituto Nazionale di Fisica Nucleare (INFN), the Università degli Studi di Milano and the University of Bern, has now performed the first interference experiment on positrons – the antimatter equivalent of electrons.

“The experiment was first proposed for electrons by Albert Einstein and Richard Feynman as a thought experiment and realized by Merli, Missiroli and Pozzi in 1976 and more systematically by Tonomura and colleagues in 1989,” explains QUPLAS spokesman Marco Giammarchi of the INFN. “In this original experiment, which was voted by Physics World as the most beautiful experiment, the researchers demonstrated the specifically quantum effect of single particle interference, which – according to Feynman – is the central ‘mystery’ of quantum theory.”

 

Antimatter quantum interferometry makes its debut, Belle Dumé, Physics World

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Quantum Robustness...

A study demonstrates that a combination of two materials, aluminum and indium arsenide, forming a device called a Josephson junction could make quantum bits more resilient. Credit: University of Copenhagen image/Antonio Fornieri

 

Topics: Computer Science, Quantum Computing, Quantum Mechanics


Researchers have been trying for many years to build a quantum computer that industry could scale up, but the building blocks of quantum computing, qubits, still aren't robust enough to handle the noisy environment of what would be a quantum computer.

A theory developed only two years ago proposed a way to make qubits more resilient through combining a semiconductor, indium arsenide, with a superconductor, aluminum, into a planar device. Now, this theory has received experimental support in a device that could also aid the scaling of qubits.

This semiconductor-superconductor combination creates a state of "topological superconductivity," which would protect against even slight changes in a qubit's environment that interfere with its quantum nature, a renowned problem called "decoherence."

The device is potentially scalable because of its flat "planar" surface – a platform that industry already uses in the form of silicon wafers for building classical microprocessors.

The work, published in Nature, was led by the Microsoft Quantum lab at the University of Copenhagen's Niels Bohr Institute, which fabricated and measured the device. The Microsoft Quantum lab at Purdue University grew the semiconductor-superconductor heterostructure using a technique called molecular beam epitaxy, and performed initial characterization measurements.

 

New robust device may scale up quantum tech, researchers say, Kayla Wiles, Purdue University

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Super State...

Super state: three independent groups have caught sight of supersolidity. (Courtesy: iStock/3quarks)

 

Topics: Bose-Einstein Condensate, Condensed Matter Physics, Electromagnetism, Quantum Mechanics


Atomic systems that behave very much like supersolids have been created independently by teams of physicists in Italy, Germany have Austria. The teams have shown that dipolar quantum gases trapped by magnetic fields can spontaneously separate into arrays of coherent droplets, providing a system closer to the original conception of a supersolid.


The supersolid phase is a counterintuitive quantum state of matter that has both crystalline order and frictionless flow at very low temperatures. The phenomenon is related to superfluidity and was predicted 50 years ago by Soviet physicists Alexander Andreev and Ilya Lifschitz. However, supersolidity has proved frustratingly difficult to observe.

In a superfluid, the energy required to create a density modulation generally increases as the modulation’s wavelength gets shorter. At one characteristic wavelength, however, the energy takes a sudden dip – much as waves pass more easily through a crystal when the wavelength equals the separation between the atoms. If the superfluid were cold enough, Andreev and Lifschitz reasoned, the energy required would drop to zero at this wavelength. The superfluid would then spontaneously separate into tiny droplets, effectively forming an ordered crystal.

 

Supersolid behavior spotted in dipolar quantum gases, Tim Wogan, Physics World

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