Hybrid Quantum Networking...

Credit: Getty Images

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

In a world’s first, researchers in France and the U.S. have performed a pioneering experiment demonstrating “hybrid” quantum networking. The approach, which unites two distinct methods of encoding information in particles of light called photons, could eventually allow for more capable and robust communications and computing.

Similar to how classical electronics can represent information as digital or analog signals, quantum systems can encode information as either discrete variables (DVs) in particles or continuous variables (CVs) in waves. Researchers have historically used one approach or the other—but not both—in any given system.

“DV and CV encoding have distinct advantages and drawbacks,” says Hugues de Riedmatten of the Institute of Photonic Sciences in Barcelona, who was not a part of the research. CV systems encode information in the varying intensity, or phasing, of light waves. They tend to be more efficient than DV approaches but are also more delicate, exhibiting stronger sensitivity to signal losses. Systems using DVs, which transmit information by the counting of photons, are harder to pair with conventional information technologies than CV techniques. They are also less error-prone and more fault-tolerant, however. Combining the two, de Riedmatten says, could offer “the best of both worlds.”

‘Hybrid’ Quantum Networking Demonstrated for First Time, Dhananjay Khadilkar, Scientific American

Majorana qubits...

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.

Quantum Time...

"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

Quantum Google...

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 and Matt O'brien, TechXPlore.com

ColdQuanta...

Lasers are used to trap arrays of atoms within glass chambers made by ColdQuanta, a neutral atom quantum computing startup. COLDQUANTA INC.

Topics: Computer Science, Laser, Quantum Computer, Quantum Mechanics

In a small basement laboratory, Harry Levine, a Harvard University graduate student in physics, can assemble a rudimentary computer in a fraction of a second. There isn't a processor chip in sight; his computer is powered by 51 rubidium atoms that reside in a glass cell the size of a matchbox. To create his computer, he lines up the atoms in single file, using a laser split into 51 beams. More lasers—six beams per atom—slow the atoms until they are nearly motionless. Then, with yet another set of lasers, he coaxes the atoms to interact with each other, and, in principle, perform calculations.

It's a quantum computer, which manipulates "qubits" that can encode zeroes and ones simultaneously in what's called a superposition state. If scaled up, it might vastly outperform conventional computers at certain tasks. But in the world of quantum computing, Levine's device is somewhat unusual. In the race to build a practical quantum device, investment has largely gone to qubits that can be built on silicon, such as tiny circuits of superconducting wire and small semiconductors structures known as quantum dots. Now, two recent studies have demonstrated the promise of the qubits Levine works with: neutral atoms. In one study, a group including Levine showed a quantum logic gate made of two neutral atoms could work with far fewer errors than ever before. And in another, researchers built 3D structures of carefully arranged atoms, showing that more qubits can be packed into a small space by taking advantage of the third dimension.

The advances, along with the arrival of venture capital funding, suggest neutral atoms could be on the upswing, says Dana Anderson, CEO of ColdQuanta, a Boulder, Colorado–based company that is developing an atom-based quantum computer. "We've done our homework," Anderson says. "This is really in the engineering arena now."

Arrays of atoms emerge as dark horse candidate to power quantum computers
Sophia Chen, Science Mag

Tunable Quantum States...

When the researchers turn an external magnetic field in different directions (indicated with arrows), they change the orientation of the linear electron flow above the kagome (six-fold) magnet, as seen in these electron wave interference patterns on the surface of a topological quantum kagome magnet. Each pattern is created by a particular direction of the external magnetic field applied on the sample.

Image by M. Z. Hasan, Jia-Xin Yin, Songtian Sonia Zhang, Princeton University

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

An international team of researchers led by Princeton physicist Zahid Hasan has discovered a quantum state of matter that can be “tuned” at will — and it’s 10 times more tuneable than existing theories can explain. This level of manipulability opens enormous possibilities for next-generation nanotechnologies and quantum computing.

“We found a new control knob for the quantum topological world,” said Hasan, the Eugene Higgins Professor of Physics. “We expect this is tip of the iceberg. There will be a new subfield of materials or physics grown out of this. … This would be a fantastic playground for nanoscale engineering.”

Hasan and his colleagues, whose research appears in the current issue of Nature, are calling their discovery a “novel” quantum state of matter because it is not explained by existing theories of material properties.

Hasan discusses the discovery with Yin and Zhang in his office in Jadwin Hall.

Photo byNick Barberio, Office of Communications

Hasan’s interest in operating beyond the edges of known physics is what attracted Jia-Xin Yin, a postdoctoral research associate and one of three co-first-authors on the paper, to his lab. Other researchers had encouraged him to tackle one of the defined questions in modern physics, Yin said.

“But when I talked to Professor Hasan, he told me something very interesting,” Yin said. “He’s searching for new phases of matter. The question is undefined. What we need to do is search for the question rather than the answer.”

The classical phases of matter — solids, liquids and gases — arise from interactions between atoms or molecules. In a quantum phase of matter, the interactions take place between electrons, and are much more complex.

“This could indeed be evidence of a new quantum phase of matter — and that’s, for me, exciting,” said David Hsieh, a professor of physics at the California Institute of Technology and a 2009 Ph.D. graduate of Princeton, who was not involved in this research. “They’ve given a few clues that something interesting may be going on, but a lot of follow-up work needs to be done, not to mention some theoretical backing to see what really is causing what they’re seeing.”

Hasan has been working in the groundbreaking subfield of topological materials, an area of condensed matter physics, where his team discovered topological quantum magnets a few years ago. In the current research, he and his colleagues “found a strange quantum effect on the new type of topological magnet that we can control at the quantum level,” Hasan said.

Princeton scientists discover a ‘tunable’ novel quantum state of matter
Liz Fuller-Wright, Office of Communications, Princeton University

Feynman Century...

Image from Science ABC dot com
"The Feynman Technique: How-to Learn Anything New in Four Easy Steps"

Topics: Quantum Computer, Richard Feynman, Nanotechnology, Nobel Prize, Quantum Mechanics

The theme of this year’s April Meeting of the American Physical Society is the “Feynman Century” because the iconoclastic, Nobel-prize-winning physicist was born in 1918. This morning at a special session devoted to Feynman, quantum computing expert Christopher Monroe of the University of Maryland spoke about early contributions to quantum computing that were made by Feynman before his untimely death in 1988.

That theme continued in an afternoon session at the conference where nuclear and particle physicists discussed how quantum computers could be applied to their work. A huge challenge to those studying the physics of quarks (quantum chromodynamics or QCD) is that it takes vast amounts of computing power just to calculate the properties of relatively simple systems.

Low barrier to entry

Quantum computers, which (at least in principle), can solve certain problems much more efficiently than conventional computers could offer a way forward. Earlier this year we reported what is probably the first-ever nuclear physics calculation done using quantum computers – the binding energy of the deuteron. Thomas Papenbrock of the University of Tennessee and Oak Ridge National Lab explained how commercial cloud quantum-computing services from IBM and Rigetti had made this calculation possible, pointing out that the barrier to entry to quantum computing is very low thanks to these services.

Quantum computing could revolutionize nuclear and particle physics, Hamish Johnston, Physics World

Single Atom Sensor...

Image Source: Link below

Topics: Atomic Physics, Quantum Computer, Quantum Mechanics, Nanotechnology

Researchers at Griffith University working with Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) have unveiled a stunningly accurate technique for scientific measurements which uses a single atom as the sensor, with sensitivity down to 100 zeptoNewtons.

(Zepto = 10^-21, or 0.000000000000000000001.)

Using highly miniaturised segmented-style Fresnel lenses - the same design used in lighthouses for more than a century - which enable exceptionally high-quality images of a single atom, the scientists have been able to detect position displacements with nanometre precision in three dimensions.

"Our atom is missing one electron, so it's very sensitive to electrical fields. By measuring the displacement, we've built a very sensitive tool for measuring electrical forces." Dr Erik Streed, of the Centre for Quantum Dynamics, explained.

"100 zeptoNewtons is a very small force. That's about the same as the force of gravity between a person in Brisbane and a person in Canberra. It can be used to investigate what's occurring on surfaces, which will help miniaturise ion trap type quantum computers and other quantum devices.

Scientists unveil high-sensitivity 3-D technique using single-atom measurements, Griffith University

Si Qubits and Quantum Computers...

Artist’s impression of the two-qubit logic gate device developed at UNSW. Each of the two electron qubits (red and blue) has a spin, or magnetic field, indicated by the arrow directions. Metal electrodes on the surface are used to manipulate the qubits, which interact to create an entangled quantum state.
(credit: Tony Melov/UNSW)

Topics: Computer Science, Quantum Computer, Quantum Mechanics

A new two-qubit quantum processor that is fully programmable and single electron spins that can be coherently coupled to individual microwave-frequency photons are two of the latest advances in the world of solid-state spin-based quantum computing. The breakthroughs could help in the development of large-scale spin-based processors in the future.

While classical computers store and process information as "bits" that can have one of two logic states – "0" or "1" – a quantum computer exploits the ability of quantum particles or bits (qubits) to be in a "superposition" of two or more states at the same time. Such a device could, in principle, outperform a classical computer on certain tasks, such as factoring large prime numbers and sorting large random lists, thanks to it being massively parallel.

In recent years, researchers have succeeded in making qubits from a number of solid-state materials, including semiconducting quantum dots and superconductors. Semiconductor spin qubits appear to be better for a number of reasons. For one, they last for a relatively long time before decohering (interacting with their environment). They can also be controlled electrically and can be integrated with high density on a chip.

The problem, however, is that it is still difficult to control the state of individual spin qubits and intertwine multiple qubits in a controlled way.

Silicon qubits show promise for quantum computers, Belle Dumé, Nanotechweb.org

To Be, or Not to Be...

Stephanie Wehner is part of the team trying to build a true quantum network across Europe. Credit: Marcel Wogram for Nature

Topics: Internet, Quantum Computer, Quantum Mechanics, Schrödinger’s cat, Theoretical Physics, Women in Science

Cultural reference: Hamlet, Act III, scene I.

The sobering part is, Europe will likely build a quantum Internet before us, China will commercialize clean energy; everywhere else will have MAGLEV (magnetic levitation) bullet trains that go 200 mph (while we're stuck with the ones that fatally crash at 80), our bridges, railroads and general infrastructure crumbling (toll road taxed to death) from a malignant narcissist, political amateur conman's claim of being "great again."

Before she became a theoretical physicist, Stephanie Wehner was a hacker. Like most people in that arena, she taught herself from an early age. At 15, she spent her savings on her first dial-up modem, to use at her parents’ home in Würzburg, Germany. And by 20, she had gained enough street cred to land a job in Amsterdam, at a Dutch Internet provider started by fellow hackers.

A few years later, while working as a network-security specialist, Wehner went to university. There, she learnt that quantum mechanics offers something that today’s networks are sorely lacking — the potential for unhackable communications. Now she is turning her old obsession towards a new aspiration. She wants to reinvent the Internet.

The ability of quantum particles to live in undefined states — like Schrödinger’s proverbial cat, both alive and dead — has been used for years to enhance data encryption. But Wehner, now at Delft University of Technology in the Netherlands, and other researchers argue that they could use quantum mechanics to do much more, by harnessing nature’s uncanny ability to link, or entangle, distant objects, and teleporting information between them. At first, it all sounded very theoretical, Wehner says. Now, “one has the hope of realizing it”.

The quantum internet has arrived (and it hasn’t), Davide Castelvecchi, Nature

Quantum Neural Network...

The Quantum Neural Network comprises a 1 km loop of optical fibre, a phase-sensitive amplifier (PSA) and a field-programmable gate array (FPGA) (Courtesy: QNNcloud)

Topics: Computer Science, Quantum Computer, Quantum Mechanics

An optical system for solving combinatorial optimization problems has been made available for use online, say its creators in Japan. Called the Quantum Neural Network (QNN), the system has been developed by Nippon Telegraph and Telephone (NTT), Japan’s National Institute of Informatics, and the University of Tokyo.

Combinatorial optimization problems involve evaluating large numbers of possible solutions to a problem and identifying the best one. A familiar example is the "travelling salesman problem" whereby a person wishes to visit several different destinations by the shortest possible route. Such problems can be found in a wide range of human endeavour from scheduling medical procedures in a hospital to maximizing the performance of a complex system like an aircraft.

Observation/Comment: In a paraphrase to "they are laughing at us," the rest of the world seems to be lapping us, technologically.

Open-access quantum computer goes live in Japan, Hamish Johnston, Physicsworld.com

10-Qubit Entanglement...

Illustration of the ten-qubit processor (Courtesy: Chao Song et al/ Physical Review Letters)

Topics: Nanotechnology, Quantum Computer, Quantum Mechanics, Superconductors

Physicists in China and the US have built a 10-qubit superconducting quantum processor that could be scaled up to tackle problems not solvable by classical computers. The performance of the device was verified using quantum tomography, which showed that the new approach can generate a true 10-partite Greenberger–Horne–Zeilinger (GHZ) state – the largest yet achieved in a solid-state system.

The field of quantum computing is in its infancy, and a genuinely useful, practical device that outperforms classical computers has not yet been built. At this stage of development, researchers do not even agree on the basics of implementation, but techniques employing superconducting circuits have an advantage over some other designs in that they are based on established and scalable microfabrication processes.

Superconducting quantum computer achieves 10-qubit entanglement
Marric Stephens, Physics World

Nanoscale Quantum Memory...

Electron microscope image of the optical cavity used to make a quantum memory. Each segment in the cavity has a vertical dimension of about 690 nm (Courtesy: Tian Zhong et al / Science)

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

A new type of optical quantum memory that could be integrated with other components on a chip has been unveiled by physicists in the US. The device overcomes an important challenge facing researchers trying to make quantum computers based on light – how to efficiently capture a photon within a sub-micron-sized structure.

From sending messages that could never be bugged to linking together quantum computers in a "quantum Internet", the ability to exchange quantum information may be vital to the future of technology. This will not be possible, however, without quantum memories to store quantum states and release them when needed.

In the Internet of today, information is sent between computers through a distributed series of nodes called routers. "Packets [of information] are maybe stored for some time and then they are sent," says Andrei Faraon of the California Institute of Technology, "There is some control over the timing of the packet." An optical network that uses photons to carry quantum information would require analogous nodes to store not strings of ones and zeroes (bits) but the full quantum states of individual photons (quantum bits or qubits).

There are currently several different quantum memories under development – some storing qubits as collective excitations in ensembles of atoms, others using solid-state crystals. Among the second group, crystals doped with ions of rare-earth metals have proved successful because rare-earth ions have sharp, stable electronic transitions that can couple to photons and preserve their quantum states. However, absorbing a photon generally requires millimetre- to centimetre-thicknesses of material, making quantum memories rather large.

Optical quantum memory shrinks to the nanoscale, Tim Wogan, Physics World

Qubit Supremacy...

Image Source: Link below

Topics: Computer Science, Quantum Computer, Quantum Mechanics

IBM Research has built its most powerful quantum chips yet, and is putting them up for use by researchers via the cloud.

The most impressive of its new chips is a prototype that uses 17 of the quantum equivalent of digital bits known as qubits. That’s up from five last year, and more than the nine that were featured in a device recently tested by Google. Like some of Google’s other latest quantum chips, IBM is starting to lay out qubits in orientations where they sit side by side. In the past it’s been hard to do that and ensure that the hardware still works, but the fact that it’s now achievable suggests that scaling up the devices even further will be plausible in the future.

The second of the new chips, pictured above, features 16 qubits, which makes it less powerful than the larger chip. But this device is robust enough that IBM is using it to upgrade its online service, which allows any researcher to test algorithms on quantum chips. The previous version of the service, which was part of the first-ever head-to-head quantum computer race, used the firm’s five-qubit chip. Meanwhile, the 17-qubit device will be opened up to just a handful of specific researchers to test.

MIT Technology Review:
IBM Nudges Ahead in the Race for Quantum Supremacy, Jamie Condliffe

Qubits Entanglement...

This photograph of the quantum device has components highlighted in false colour. The superconducting qubits are numbered 1–10 and the central bus resonator is labelled "B". The red and blue structures are control lines for the individual qubits. (Courtesy: Chao Song et al/ arXiv: 1703.10302)

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

A group of physicists in China has taken the lead in the race to couple together increasing numbers of superconducting qubits. The researchers have shown that they can entangle 10 qubits connected to one another via a central resonator – so beating the previous record by one qubit – and say that their result paves the way to quantum simulators that can calculate the behaviour of small molecules and other quantum-mechanical systems much more efficiently than even the most powerful conventional computers.

Superconducting circuits create qubits by superimposing two electrical currents, and hold the promise of being able to fabricate many qubits on a single chip through the exploitation of silicon-based manufacturing technology. In the latest work, a multi-institutional group led by Jian-Wei Pan of the University of Science and Technology of China in Hefei, built a circuit consisting of 10 qubits, each half a millimetre across and made from slivers of aluminium laid on to a sapphire substrate. The qubits, which act as non-linear LC oscillators, are arranged in a circle around a component known as a bus resonator.

Initially, the qubits are put into a superposition state of two oscillating currents with different amplitudes by supplying each of them with a very low-energy microwave pulse. To avoid interference at this stage, each qubit is set to a different oscillation frequency. However, for the qubits to interact with one another, they need to have the same frequency. This is where the bus comes in. It allows qubits to transfer energy from one another, but does not absorb any of that energy itself.

Physics World: Ten superconducting qubits entangled by physicists in China
Edwin Cartlidge

Ions, Lasers and Time Crystals...

Researchers have created the world's first time crystal, an exotic state of matter that combines the rigidity of an ordinary crystal with a regular rhythm in time. (Credit: E. Edwards/JQI)

Topics: Applied Physics, Computer Science, Quantum Computer, Quantum Mechanics, Theoretical Physics

Consider, for a moment, the humble puddle of water. If you dive down to nearly the scale of molecules, it will be hard to tell one spot in the puddle from any other. You can shift your gaze to the left or right, or tilt your head, and the microscopic bustle will be identical—a situation that physicists call highly symmetric.

That all changes abruptly when the puddle freezes. In contrast to liquid water, ice is a crystal, and it gains a spontaneous rigid structure as the temperature drops. Freezing fastens neighboring water molecules together in a regular pattern, and a simple tilt of the head now creates a kaleidoscopic change.

In 2012, Nobel-prize winning physicist Frank Wilczek, a professor at the Massachusetts Institute of Technology, proposed something that sounds pretty strange. It might be possible, Wilczek argued, to create crystals that are arranged in time instead of space. The suggestion prompted years of false starts and negative results that ruled out some of the most obvious places to look for these newly named time crystals.

Now, five years after the first proposal, a team of researchers led by physicists at the Joint Quantum Institute and the University of Maryland have created the world's first time crystal using a chain of atomic ions. The result, which finally brings Wilczek's exotic idea to life, was reported in Nature on March 9.

Much like freezing destroys the symmetry of liquid water, a time crystal disturbs a regularity in time. This is somewhat surprising, says lead author and JQI postdoctoral researcher Jiehang Zhang, since nature usually responds in sync to things that change in time. "The earth rotates around the sun once a year, and the seasons have the same period," Zhang says. "That’s what you would naturally expect."

A time crystal doesn't follow the lead, instead responding with a slower frequency—like a bell struck once a second that rings every other second. The atomic ions in the Maryland experiment, which researchers manipulated using laser pulses, responded exactly half as fast as the sequence of pulses that drove them.

Joint Quantum Institute: Ions sync up into world's first time crystal

#P4TC:

Recipe For Time Crystals, January 24, 2017
Time Crystals, October 13, 2016

More Bang For Your Bit...

Image credits:
Composite image by Yuen Yiu, Staff Writer and Abigail Malate, Staff Illustrator. Fiber-Optic photo by Matthew.nq/Wikimedia , (CC by 4.0)

Topics: Computer Science, Internet, Quantum Computer, Quantum Mechanics

Scientists break the record for data transfer efficiency by using photons and quantum communication techniques.

Scientists from Oak Ridge National Laboratory in Tennessee have broken the efficiency record for data transfer. Using a quantum communication process known as superdense coding, they squeezed through an average 1.67 bits of data per qubit. Qubits, which is short for "quantum bits," are units of data that utilize quantum properties to store information.

The result beats the previous record of 1.63 bits per qubit. Even more importantly, the experiment used only simple, off-the-shelf technology, taking quantum communication closer to practical applications in the future. The work will appear in Physical Review Letters.

More bang for your bit

Computers send information in units called bits, which represent either a one or a zero. These bits can be understood as gumballs that one party (Alice) sends to another party (Bob). In a classical system, Bob would register a one if he receives a gumball and a zero for a space between gumballs. However, these gumballs also contain other properties that are not communicated in the classical system, such as color or flavor. The properties are analogous to quantum properties such as polarization or angular momentum, which can be found in the photons and electrons we use to transfer data today.

"We're basically trying to see what quantum abilities there are, and try to see what can we use them for," said Brian Williams, a quantum physicist from Oak Ridge National Laboratory. He is the lead author of the paper.

Inside Science: Same Spark, More Bytes, Yuen Yiu

Recipe For Time Crystals...

Figure 1: Yao et al. [7] have developed a blueprint for creating a time crystal and a method for detecting it, which has been followed by two experimental groups [8, 9]. Quantum spins are subjected to imperfect spin-flip driving pulses and then allowed to interact with each other in the presence of strong random disorder in the local magnetic fields. The sequence repeats after a total time period T, but the spin system exhibits emergent oscillations with period 2T—the hallmark of a discrete quantum time crystal. [Credit: APS/Alan Stonebraker/Phil Richerme]

Topics: Computer Science, Quantum Computer, Quantum Mechanics, Theoretical Physics

A detailed theoretical recipe for making time crystals has been unveiled and swiftly implemented by two groups using vastly different experimental systems.

The story of time crystals—whose lowest-energy configurations are periodic in time rather than space—epitomizes the creative ideas, controversy, and vigorous discussion that lie at the core of the scientific process. Originally theorized by Frank Wilczek in 2012 [1] (see 15 October 2012 Viewpoint), time crystals were met with widespread attention, but also a healthy dose of skepticism [2]. This ignited a debate in the literature, culminating in a proof that time crystals cannot exist in thermal equilibrium, as originally imagined by Wilczek [3]. But the tale did not end there. It was later argued that time crystals might still be possible in periodically driven systems, which can never reach thermal equilibrium [4–6]. Three recent papers have now completed the story, one proposing a roadmap for creating a nonequilibrium time crystal in the lab [7], and two describing subsequent experimental demonstrations in systems of trapped ions [8] and spin impurities in diamond [9] (both posted on the physics arXiv preprint server).

Empty space exhibits continuous translation symmetry: nothing distinguishes one point from any other. Yet ordinary crystals break this symmetry because atoms are periodically arranged in specific locations and display long-range spatial correlations. Given that we live in four-dimensional spacetime, it is natural to wonder if an analogous process of crystallization and symmetry breaking can arise along the time dimension as well [1]. If it does, then any such time crystal should return back to its initial state at specific times, while spontaneously locking to an oscillation period that differs from that of any external time-dependent forces. Hence this definition excludes all known classical oscillatory systems such as waves or driven pendulums.

APS Physics Viewpoint: How to Create a Time Crystal, Phil Richerme
#P4TC: Time Crystals, October 13, 2016

Squeezing Below The Quantum Limit...

NIST researchers applied a special form of microwave light to cool a microscopic aluminum drum to an energy level below the generally accepted limit, to just one fifth of a single quantum of energy. Having a diameter of 20 micrometers and a thickness of 100 nanometers, the drum beat 10 million times per second while its range of motion fell to nearly zero.

Credit: Teufel/NIST

Topics: Metamaterials, Nanotechnology, Quantum Computer, Quantum Mechanics

Physicists at the National Institute of Standards and Technology (NIST) have cooled a mechanical object to a temperature lower than previously thought possible, below the so-called “quantum limit.”

The new NIST theory and experiments, described in the Jan. 12, 2017, issue of Nature, showed that a microscopic mechanical drum—a vibrating aluminum membrane—could be cooled to less than one-fifth of a single quantum, or packet of energy, lower than ordinarily predicted by quantum physics. The new technique theoretically could be used to cool objects to absolute zero, the temperature at which matter is devoid of nearly all energy and motion, NIST scientists said.

“The colder you can get the drum, the better it is for any application,” said NIST physicist John Teufel, who led the experiment. “Sensors would become more sensitive. You can store information longer. If you were using it in a quantum computer, then you would compute without distortion, and you would actually get the answer you want.”

NIST Physicists ‘Squeeze’ Light to Cool Microscopic Drum Below Quantum Limit
Laura Ost

Quantum Brain...

davidope for Quanta Magazine

Topics: Biology, Neuroscience, Quantum Computer, Quantum Mechanics

Note: With the exception of the historical links below, I don't have anything related to physics and Thanksgiving. Enjoy the food and links. Travel safe.

The mere mention of “quantum consciousness” makes most physicists cringe, as the phrase seems to evoke the vague, insipid musings of a New Age guru. But if a new hypothesis proves to be correct, quantum effects might indeed play some role in human cognition. Matthew Fisher, a physicist at the University of California, Santa Barbara, raised eyebrows late last year when he published a paper in Annals of Physics proposing that the nuclear spins of phosphorus atoms could serve as rudimentary “qubits” in the brain — which would essentially enable the brain to function like a quantum computer.

As recently as 10 years ago, Fisher’s hypothesis would have been dismissed by many as nonsense. Physicists have been burned by this sort of thing before, most notably in 1989, when Roger Penrose proposed that mysterious protein structures called “microtubules” played a role in human consciousness by exploiting quantum effects. Few researchers believe such a hypothesis plausible. Patricia Churchland, a neurophilosopher at the University of California, San Diego, memorably opined that one might as well invoke “pixie dust in the synapses” to explain human cognition.

Quanta Magazine: A New Spin on the Quantum Brain, Jennifer Ouellette

Completely unrelated to anything but the day:

Manataka American Indian Council on Thanksgiving
What Really Happened at the First Thanksgiving? The Wampanoag Side of the Tale
Gale Tourey Toensing