. Scientific Frontline: Quantum Science
Showing posts with label Quantum Science. Show all posts
Showing posts with label Quantum Science. Show all posts

Wednesday, November 23, 2022

Spin correlation between paired electrons demonstrated

Electrons leave a superconductor only as pairs with opposite spins. If both electron paths are blocked for the same type of spin by parallel spin filters, paired electrons from the superconductor are blocked and the currents decrease.
Image Credit: University of Basel, Department of Physics/Scixel

Physicists at the University of Basel have experimentally demonstrated for the first time that there is a negative correlation between the two spins of an entangled pair of electrons from a superconductor. For their study, the researchers used spin filters made of nanomagnets and quantum dots, as they report in the scientific journal Nature.

The entanglement between two particles is among those phenomena in quantum physics that are hard to reconcile with everyday experiences. If entangled, certain properties of the two particles are closely linked, even when far apart. Albert Einstein described entanglement as a “spooky action at a distance”. Research on entanglement between light particles (photons) was awarded this year's Nobel Prize in Physics.

Two electrons can be entangled as well – for example in their spins. In a superconductor, the electrons form so-called Cooper pairs responsible for the lossless electrical currents and in which the individual spins are entangled.

For several years, researchers at the Swiss Nanoscience Institute and the Department of Physics at the University of Basel have been able to extract electron pairs from a superconductor and spatially separate the two electrons. This is achieved by means of two quantum dots – nanoelectronic structures connected in parallel, each of which only allows single electrons to pass.

Monday, November 21, 2022

A possible game changer for next generation microelectronics

Magnetic fields created by skyrmions in two-dimensional sheet of material composed of iron, germanium and tellurium.
Image Credit: Argonne National Laboratory.

Magnets generate invisible fields that attract certain materials. A common example is fridge magnets. Far more important to our everyday lives, magnets also can store data in computers. Exploiting the direction of the magnetic field (say, up or down), microscopic bar magnets each can store one bit of memory as a zero or a one — the language of computers.

Scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory wants to replace the bar magnets with tiny magnetic vortices. As tiny as billionths of a meter, these vortices are called skyrmions, which form in certain magnetic materials. They could one day usher in a new generation of microelectronics for memory storage in high performance computers.

“We estimate the skyrmion energy efficiency could be 100 to 1000 times better than current memory in the high-performance computers used in research.” — Arthur McCray, Northwestern University graduate student working in Argonne’s Materials Science Division

“The bar magnets in computer memory are like shoelaces tied with a single knot; it takes almost no energy to undo them,” said Arthur McCray, a Northwestern University graduate student working in Argonne’s Materials Science Division (MSD). And any bar magnets malfunctioning due to some disruption will affect the others.

New quantum tool developed in groundbreaking experimental achievement

SFLORG Stock Photo

For the first time in experimental history, researchers at the Institute for Quantum Computing (IQC) have created a device that generates twisted neutrons with well-defined orbital angular momentum. Previously considered an impossibility, this groundbreaking scientific accomplishment provides a brand-new avenue for researchers to study the development of next-generation quantum materials with applications ranging from quantum computing to identifying and solving new problems in fundamental physics.

“Neutrons are a powerful probe for the characterization of emerging quantum materials because they have several unique features,” said Dr. Dusan Sarenac, research associate with IQC and technical lead, Transformative Quantum Technologies at the University of Waterloo. “They have nanometer-sized wavelengths, electrical neutrality, and a relatively large mass. These features mean neutrons can pass through materials that X-rays and light cannot.”

While methods for the experimental production and analysis of orbital angular momentum in photons and electrons are well-studied, a device design using neutrons has never been demonstrated until now. Because of their distinct characteristics, the researchers had to construct new devices and create novel methods for working with neutrons.

Friday, November 18, 2022

Scientists closer to solving a superconducting puzzle with applications in medicine, transport and power transmission

Particle accelerator
Source: University of Bristol

Researchers studying the magnetic behavior of a cuprate superconductor may have explained some of the unusual properties of their conduction electrons.

Cuprate superconductors are used in levitating trains, quantum computing and power transmission. They are of a family of materials made of layers of copper oxides alternating with layers of other metal oxides, which act as charge reservoirs.

The largest use of superconductors is currently for manufacturing superconducting magnets used for medical MRI machines and for scientific applications such as particle accelerators.

For the potential applications of superconducting materials to be fully realized, developing superconductors that maintain their properties at higher temperatures is crucial for scientists. The cuprate superconductors currently exhibit relatively high transition point temperatures and therefore give scientists an opportunity to study what makes higher temperature superconductivity possible.

Tuesday, November 15, 2022

Unimon - A new qubit to boost quantum computers for useful applications

Artistic impression of a unimon qubit in a quantum processor.
Illustration Credit: Aleksandr Kakinen.

A group of scientists from Aalto University, IQM Quantum Computers, and VTT Technical Research Centre of Finland have discovered a new superconducting qubit, the unimon, to increase the accuracy of quantum computations

A group of scientists from Aalto University, IQM Quantum Computers, and VTT Technical Research Centre have discovered a new superconducting qubit, the unimon, to increase the accuracy of quantum computations. The team has achieved the first quantum logic gates with unimons at 99.9% fidelity — a major milestone on the quest to build commercially useful quantum computers. This pivotal piece of research was just published in the journal Nature Communications.

Of all the different approaches to building useful quantum computers, superconducting qubits are on the lead. However, the qubit designs and techniques currently used do not yet provide high enough performance for practical applications. In this noisy intermediate-scale quantum (NISQ) era, the complexity of the implementable quantum computations is mostly limited by errors in single- and two-qubit quantum gates. The quantum computations need to become more accurate to be useful.

Tuesday, November 8, 2022

New quantum phase discovered for developing hybrid materials

 Metropolitan University Scientists have discovered that in Ba1-xSrxAl2O4, a highly disordered atomic arrangement is formed in the AlO4 network at chemical compositions near the structural quantum critical point, resulting in both characteristics of crystalline and amorphous materials.
Illustration Credit: Yui Ishii, Osaka

Scientists discovered a hybrid state in which crystals exhibit both crystalline and amorphous characteristics near the structural quantum critical point.

If you have ever watched water freeze to ice, you have witnessed what physicists call a “phase transition.” Osaka Metropolitan University scientists have discovered an unprecedented phase transition during which crystals achieve amorphous characteristics while retaining their crystalline properties. Their findings contribute to developing hybrid materials for use in harsh environments, such as outer space. The results were published in Physical Review B.

A typical phase transition exhibited by crystalline solids involves a change in the crystal structure. Such structural phase transitions usually occur at finite temperatures. However, controlling the chemical composition of the crystal can lower the transition temperature to absolute zero (−273°C). The transition point at absolute zero is called the structural quantum critical point.

Monday, November 7, 2022

Scientists discover exotic quantum state at room temperature

Researchers at Princeton discovered a material, made from the elements bismuth and bromine, that allows specialized quantum behaviors — usually seen only under high pressures and temperatures near absolute zero — to appear at room temperature. 
Photo Credit: Shafayat Hossain and M. Zahid Hasan, Princeton University

For the first time, physicists have observed novel quantum effects in a topological insulator at room temperature. This finding opens up a new range of possibilities for the development of efficient quantum technologies, such as spin-based electronics, which may potentially replace many current electronic systems for higher energy efficiency.

The breakthrough, published as the cover article of the October issue of Nature Materials, came when Princeton scientists explored a topological material based on the element bismuth.

The scientists have used topological insulators to demonstrate quantum effects for more than a decade, but this experiment is the first time these effects have been observed at room temperature. Typically, inducing and observing quantum states in topological insulators requires temperatures around absolute zero, which is equal to minus 459 degrees Fahrenheit (or -273 degrees Celsius).

In recent years, the study of topological states of matter has attracted considerable attention among physicists and engineers and is presently the focus of much international interest and research. This area of study combines quantum physics with topology — a branch of theoretical mathematics that explores geometric properties that can be deformed but not intrinsically changed.

“The novel topological properties of matter have emerged as one of the most sought-after treasures in modern physics, both from a fundamental physics point of view and for finding potential applications in next-generation quantum engineering and nanotechnologies,” said M. Zahid Hasan, the Eugene Higgins Professor of Physics at Princeton University, led the research. “This work was enabled by multiple innovative experimental advances in our lab at Princeton.”

Wednesday, November 2, 2022

Method to char­ac­ter­ize large quan­tum com­put­ers

View inside an ion trap, the heart of an ion trap quantum computer. 
Credit: C Lackner/Quantum Optics and Spectroscopy Group, University of Innsbruck

Quantum devices are becoming ever more complex and powerful. Researchers at the University of Innsbruck, in collaboration with the Johannes Kepler University Linz and the University of Technology Sydney, are now presenting a method to characterize even large quantum computers using only a single measurement setting.

The gold-standard for the characterization of quantum devices is so-called quantum tomography, which in analogy to medical tomography, can draw a complete picture of a quantum system from a series of snapshots of the system. While offering plenty of insights, the number of measurements required for tomography increases rapidly, with three times as many measurements required for every additional qubit. Due to the sheer time it takes to perform all these measurements, tomography has only been possible on devices with a handful of qubits. However, recent developments on quantum computers have successfully scaled up system sizes much beyond the capabilities of tomography, making their characterization a daunting bottleneck.

Monday, October 24, 2022

High-tech sensors could guide vehicles without satellites, if they can handle the ride

Sandia National Laboratories atomic physicist Jongmin Lee examines the sensor head of a cold-atom interferometer that could help vehicles stay on course where GPS is unavailable.
Photo credit: Bret Latter

Words like “tough” or “rugged” are rarely associated with a quantum inertial sensor. The remarkable scientific instrument can measure motion a thousand times more accurately than the devices that help navigate today’s missiles, aircraft and drones. But its delicate, table-sized array of components that includes a complex laser and vacuum system has largely kept the technology grounded and confined to the controlled settings of a lab.

Jongmin Lee wants to change that.

The atomic physicist is part of a team at Sandia National Laboratories that envisions quantum inertial sensors as revolutionary, onboard navigational aids. If the team can reengineer the sensor into a compact, rugged device, the technology could safely guide vehicles where GPS signals are jammed or lost.

In a major milestone toward realizing their vision, the team has successfully built a cold-atom interferometer, a core component of quantum sensors, designed to be much smaller and tougher than typical lab setups. The team describes their prototype in the academic journal Nature Communications, showing how to integrate several normally separated components into a single monolithic structure. In doing so, they reduced the key components of a system that existed on a large optical table down to a sturdy package roughly the size of a shoebox.

Thursday, October 20, 2022

Our brains use quantum computation

Scientists from Trinity believe our brains could use quantum computation after adapting an idea developed to prove the existence of quantum gravity to explore the human brain and its workings. The discovery may shed light on consciousness, the workings of which remain scientifically difficult to understand and explain. Quantum brain processes could also explain why we can still outperform supercomputers when it comes to unforeseen circumstances, decision making, or learning something new

Scientists from Trinity believe our brains could use quantum computation after adapting an idea developed to prove the existence of quantum gravity to explore the human brain and its workings.

The brain functions measured were also correlated to short-term memory performance and conscious awareness, suggesting quantum processes are also part of cognitive and conscious brain functions.

If the team’s results can be confirmed – likely requiring advanced multidisciplinary approaches –they would enhance our general understanding of how the brain works and potentially how it can be maintained or even healed. They may also help find innovative technologies and build even more advanced quantum computers.

Tuesday, October 18, 2022

New laboratory to explore the quantum mysteries of nuclear materials

INL researchers have built a laboratory around molecular beam epitaxy (MBE), a process that creates ultra-thin layers of materials with a high degree of purity and control.
Credit: Idaho National Laboratory

Replete with tunneling particles, electron wells, charmed quarks and zombie cats, quantum mechanics takes everything Sir Isaac Newton taught about physics and throws it out the window.

Every day, researchers discover new details about the laws that govern the tiniest building blocks of the universe. These details not only increase scientific understanding of quantum physics, but they also hold the potential to unlock a host of technologies, from quantum computers to lasers to next-generation solar cells.

But there’s one area that remains a mystery even in this most mysterious of sciences: the quantum mechanics of nuclear fuels.

Exploring the frontiers of quantum mechanics

Until now, most fundamental scientific research of quantum mechanics has focused on elements such as silicon because these materials are relatively inexpensive, easy to obtain and easy to work with.

Now, Idaho National Laboratory researchers are planning to explore the frontiers of quantum mechanics with a new synthesis laboratory that can work with radioactive elements such as uranium and thorium.

Tuesday, October 11, 2022

Bristol researchers make important breakthrough in quantum computing

Researchers from the University of Bristol, quantum start-up, Phasecraft and Google Quantum AI have revealed properties of electronic systems that could be used for the development of more efficient batteries and solar cells.

The findings, published in Nature Communications today, describes how the team has taken an important first step towards using quantum computers to determine low-energy properties of strongly-correlated electronic systems that cannot be solved by classical computers. They did this by developing the first truly scalable algorithm for observing ground-state properties of the Fermi-Hubbard model on a quantum computer. The Fermi-Hubbard model is a way of discovering crucial insights into electronic and magnetic properties of materials.

Modeling quantum systems of this form has significant practical implications, including the design of new materials that could be used in the development of more effective solar cells and batteries, or even high-temperature superconductors. However, doing so remains beyond the capacity of the world’s most powerful supercomputers. The Fermi-Hubbard model is widely recognized as an excellent benchmark for near-term quantum computers because it is the simplest materials system that includes non-trivial correlations beyond what is captured by classical methods. Approximately producing the lowest-energy (ground) state of the Fermi-Hubbard model enables the user to calculate key physical properties of the model.

In the past, researchers have only succeeded in solving small, highly simplified Fermi-Hubbard instances on a quantum computer. This research shows that much more ambitious results are possible. Leveraging a new, highly efficient algorithm and better error-mitigation techniques, they successfully ran an experiment that is four times larger – and consists of 10 times more quantum gates – than anything previously recorded.

Thursday, October 6, 2022

Boron Nitride with a Twist Could Lead to New Way to Make Qubits

Shaul Aloni, Cong Su, Alex Zettl, and Steven Louie at the Molecular Foundry. The researchers synthesized a device made from twisted layers of hexagonal boron nitride with color centers that can be switched on and off with a simple switch.
Credit: Marilyn Sargent/Berkeley Lab

Achieving scalability in quantum processors, sensors, and networks requires novel devices that are easily manipulated between two quantum states. A team led by researchers from the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) has now developed a method, using a solid-state “twisted” crystalline layered material, which gives rise to tiny light-emitting points called color centers. These color centers can be switched on and off with the simple application of an external voltage.

“This is a first step toward a color center device that engineers could build or adapt into real quantum systems,” said Shaul Aloni, a staff scientist at Berkeley Lab’s Molecular Foundry, who co-led the study. The work is detailed in the journal Nature Materials.

For example, the research could lead to a new way to make quantum bits, or qubits, which encode information in quantum computers.

Color centers are microscopic defects in a crystal, such as diamond, that usually emit bright and stable light of specific color when struck with laser or other energy source such as an electron beam. Their integration with waveguides, devices that guide light, can connect operations across a quantum processor. Several years ago, researchers discovered that color centers in a synthesized material called hexagonal boron nitride (hBN), which is commonly used as a lubricant or additive for paints and cosmetics, emitted even brighter colors than color centers in diamond. But engineers have struggled to use the material in applications because producing the defects at a determined location is difficult, and they lacked a reliable way to switch the color centers on and off.

Friday, September 30, 2022

New Superconducting Qubit Testbed Benefits Quantum Information Science Development

A superconducting qubit sits in a dilution refrigerator in a Pacific Northwest National Laboratory (PNNL) physics lab. This experimental device is the first step in establishing a qubit testbed at PNNL.
  Photo Credit: Andrea Starr | Pacific Northwest National Laboratory

If you’ve ever tried to carry on a conversation in a noisy room, you’ll be able to relate to the scientists and engineers trying to “hear” the signals from experimental quantum computing devices called qubits. These basic units of quantum computers are early in their development and remain temperamental, subject to all manner of interference. Stray “noise” can masquerade as a functioning qubit or even render it inoperable.

That’s why physicist Christian Boutan and his Pacific Northwest National Laboratory (PNNL) colleagues were in celebration mode recently as they showed off PNNL’s first functional superconducting qubit. It’s not much to look at. Its case—the size of a pack of chewing gum--is connected to wires that transmit signals to a nearby panel of custom radiofrequency receivers. But most important, it’s nestled within a shiny gold cocoon called a dilution refrigerator and shielded from stray electrical signals. When the refrigerator is running, it is among the coldest places on Earth, so very close to absolute zero, less than 6 millikelvin (about −460 degrees F).

Thursday, September 22, 2022

Conventional Computers Can Learn to Solve Tricky Quantum Problems

Hsin-Yuan (Robert) Huang
Credit: Caltech

There has been a lot of buzz about quantum computers and for good reason. The futuristic computers are designed to mimic what happens in nature at microscopic scales, which means they have the power to better understand the quantum realm and speed up the discovery of new materials, including pharmaceuticals, environmentally friendly chemicals, and more. However, experts say viable quantum computers are still a decade away or more. What are researchers to do in the meantime?

A new Caltech-led study in the journal Science describes how machine learning tools, run on classical computers, can be used to make predictions about quantum systems and thus help researchers solve some of the trickiest physics and chemistry problems. While this notion has been proposed before, the new report is the first to mathematically prove that the method works in problems that no traditional algorithms could solve.

"Quantum computers are ideal for many types of physics and materials science problems," says lead author Hsin-Yuan (Robert) Huang, a graduate student working with John Preskill, the Richard P. Feynman Professor of Theoretical Physics and the Allen V. C. Davis and Lenabelle Davis Leadership Chair of the Institute for Quantum Science and Technology (IQIM). "But we aren't quite there yet and have been surprised to learn that classical machine learning methods can be used in the meantime. Ultimately, this paper is about showing what humans can learn about the physical world."

Tuesday, September 20, 2022

Creating diamonds to shed light on the quantum world

Sandia National Laboratories’ Andy Mounce makes microscopic sensors to try to understand quantum materials at the Center for Integrated Nanotechnologies. He is one of four employees to earn DOE’s Early Career Research Award.
Photo credit: Bret Latter

Diamonds are a scientist’s best friend. That much is at least true for physicist Andy Mounce, whose work with diamond quantum sensors at Sandia National Laboratories has earned him the DOE’s Early Career Research Award.

As a scientist in Sandia’s Center for Integrated Nanotechnologies, he specializes in making microscopic sensors to try to understand the nature of quantum materials and their electrons’ behavior. Mounce is an expert in creating nitrogen-vacancy defects in artificial diamonds, which are extremely sensitive to the electric and magnetic fields at a nanoscale.

“With these quantum sensors we can study basic properties of low dimensional quantum materials, such as superconducting phases, magnetic phases,” he said. “A quantum material can be anything from a nanostructure to a large material that just has electrons that interact with each other very strongly. The distinguishing property of a quantum material, is that their behavior is defined by quantum mechanics, so not your typical copper conductor”.

Saturday, September 17, 2022

The magneto-optic modulator

Electricity flowing through a metal coil generates electric (purple) and magnetic (faint green) fields. This changes the properties of the substrate, which tunes the resonance ring (red) to different frequencies. The whole setup enables the scientists to convert a continuous beam of light (red on left) into pulses that can carry data through a fiber-optic cable. 
Photo Credit: Brian Long

Many state-of-the-art technologies work at incredibly low temperatures. Superconducting microprocessors and quantum computers promise to revolutionize computation, but scientists need to keep them just above absolute zero (-459.67° Fahrenheit) to protect their delicate states. Still, ultra-cold components have to interface with room temperature systems, providing both a challenge and an opportunity for engineers.

An international team of scientists, led by UC Santa Barbara’s Paolo Pintus, has designed a device to help cryogenic computers talk with their fair-weather counterparts. The mechanism uses a magnetic field to convert data from electrical current to pulses of light. The light can then travel via fiber-optic cables, which can transmit more information than regular electrical cables while minimizing the heat that leaks into the cryogenic system. The team’s results appear in the journal Nature Electronics.

The Building Blocks for Exploring New Exotic States of Matter

Using the High Flux Isotope Reactor’s DEMAND instrument, neutron scattering studies identified the crystal & magnetic structure of an intrinsic ferromagnetic topological insulator MnBi8Te13. The last column of inset shows its crystal & magnetic structures
Image credit: Oak Ridge National Laboratory.

Topological insulators act as electrical insulators on the inside but conduct electricity along their surfaces. Researchers study some of these insulators’ exotic behavior using an external magnetic field to force the ion spins within a topological insulator to be parallel to each other. This process is known as breaking time-reversal symmetry. Now, a research team has created an intrinsic ferromagnetic topological insulator. This means the time-reversal symmetry is broken without applying a magnetic field. The team employed a combination of synthesis, characterization tools, and theory to confirm the structure and properties of new magnetic topological materials. In the process, they discovered an exotic axion insulator in MnBi8Te13.

Researchers can use magnetic topological materials to realize exotic forms of matter that are not seen in other types of material. Scientists believe that the phenomena these materials exhibit could help advance quantum technology and increase the energy efficiency of future electronic devices. Researchers believe that a topological insulator that is inherently ferromagnetic, rather than gaining its properties by adding small numbers of magnetic atoms, is ideal for studying novel topological behaviors. This is because no external magnetic field is needed to study the material’s properties. It also means the material’s magnetism is more uniformly distributed. However, scientists have previously faced challenges in creating this kind of material. This new material consists of layers of manganese, bismuth, and tellurium atoms. It could provide opportunities for exploring novel phases of matter and developing new technologies. It also helps researchers study basic scientific questions about quantum materials.

Monday, September 12, 2022

Through the quantum looking glass

Green laser light illuminates a metasurface that is a hundred times thinner than paper, that was fabricated at the Center for Integrated Nanotechnologies. CINT is jointly operated by Sandia and Los Alamos national laboratories for the Department of Energy Office of Science.
Photo credit: Craig Fritz

An ultrathin invention could make future computing, sensing and encryption technologies remarkably smaller and more powerful by helping scientists control a strange but useful phenomenon of quantum mechanics, according to new research recently published in the journal Science.

Scientists at Sandia National Laboratories and the Max Planck Institute for the Science of Light have reported on a device that could replace a roomful of equipment to link photons in a bizarre quantum effect called entanglement. This device — a kind of nano-engineered material called a metasurface — paves the way for entangling photons in complex ways that have not been possible with compact technologies.

When scientists say photons are entangled, they mean they are linked in such a way that actions on one affect the other, no matter where or how far apart the photons are in the universe. It is an effect of quantum mechanics, the laws of physics that govern particles and other very tiny things.

Although the phenomenon might seem odd, scientists have harnessed it to process information in new ways. For example, entanglement helps protect delicate quantum information and correct errors in quantum computing, a field that could someday have sweeping impacts in national security, science and finance. Entanglement also enables new, advanced encryption methods for secure communication.

Wednesday, September 7, 2022

New measurements point to silicon as a major contributor to performance limitations in superconducting quantum processors

A superconducting-based quantum processor, composed of several thin film materials deposited on top of a silicon substrate.
Photo credit: Rigetti Computing

Silicon is a material widely used in computing: It is used in computer chips, circuits, displays and other modern computing devices. Silicon is also used as the substrate, or the foundation of quantum computing chips.

Researchers at the Superconducting Quantum Materials and Systems Center, hosted by the U.S. Department of Energy’s Fermi National Accelerator Laboratory, demonstrated that silicon substrates could be detrimental to the performance of quantum processors. SQMS Center scientists have measured silicon’s effect on the lifespan of qubits with parts-per-billion precision. These findings have been published in Physical Review Applied.

New approaches to computing

Calculations once performed on pen and paper have since been handed to computers. Classical computers rely on bits, 1 or 0, which have limitations. Quantum computers offer a new approach to computing that relies on quantum mechanics. These novel devices could perform calculations that would take years or be practically impossible for a classical computer to perform.

Using the power of quantum mechanics, qubits—the basic unit of quantum information held within a quantum computing chip—can be both a 1 and a 0 at the same time. Processing and storing information in qubits is challenging and requires a well-controlled environment. Small environmental disturbances or flaws in the qubit’s materials can destroy the information.

Qubits require near-perfect conditions to maintain the integrity of their quantum state, and certain material properties can decrease the qubit lifespan. This phenomenon, called quantum decoherence, is a critical obstacle to overcome to operate quantum processors.

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