International team visualizes properties of plant cell walls at nanoscale

Scattering-type scanning near-field optical microscopy, a nondestructive technique in which the tip of the probe of a microscope scatters pulses of light to generate a picture of a sample, allowed the team to obtain insights into the composition of plant cell walls.
Credit: Ali Passian/ORNL, U.S. Dept. of Energy

To optimize biomaterials for reliable, cost-effective paper production, building construction, and biofuel development, researchers often study the structure of plant cells using techniques such as freezing plant samples or placing them in a vacuum. These methods provide valuable data but often cause permanent damage to the samples.

A team of physicists including Ali Passian, a research scientist at the Department of Energy’s Oak Ridge National Laboratory, and researchers from the French National Centre for Scientific Research, or CNRS, used state-of-the-art microscopy and spectroscopy methods to provide nondestructive alternatives. Using a technique called scattering-type scanning near-field optical microscopy, the team examined the composition of cell walls from young poplar trees without damaging the samples.

But the team still had other obstacles to overcome. Although plant cell walls are notoriously difficult to navigate due to the presence of complex polymers such as microfibrils — thin threads of biomass that Passian describes as a maze of intertwined spaghetti strings — the team reached a resolution better than 20 nanometers, or about a thousand times smaller than a strand of human hair. This detailed view allowed the researchers to detect optical properties of plant cell materials for the first time across regions large and small, even down to the width of a single microfibril. Their results were published in Communications Materials.

Bumps could smooth quantum investigations

Stamping or growing 2D materials onto a patterned surface could create models for 1D systems suitable for the exploration of quantum effects, according to a new theory by Rice University engineers. The “bumps” would manipulate the flow of electrons into bands that mimic 1D semiconductors.
Credit: Yakobson Research Group/Rice University

Atoms do weird things when forced out of their comfort zones. Rice University engineers have thought up a new way to give them a nudge.

Materials theorist Boris Yakobson and his team at Rice’s George R. Brown School of Engineering have a theory that changing the contour of a layer of 2D material, thus changing the relationships between its atoms, might be simpler to do than previously thought.

While others twist 2D bilayers -- two layers stacked together -- of graphene and the like to change their topology, the Rice researchers suggest through computational models that growing or stamping single-layer 2D materials on a carefully designed undulating surface would achieve “an unprecedented level of control” over their magnetic and electronic properties.

They say the discovery opens a path to explore many-body effects, the interactions between multiple microscopic particles, including quantum systems.

The paper by Yakobson and two alumni, co-lead author Sunny Gupta and Henry Yu, of his lab appears in Nature Communications.

Breakthrough paves way for photonic sensing at the ultimate quantum limit

Photonic chip with a microring resonator nanofabricated in a commercial foundry.
Photo credit: Joel Tasker, QET Labs

A Bristol-led team of physicists has found a way to operate mass manufacturable photonic sensors at the quantum limit. This breakthrough paves the way for practical applications such as monitoring greenhouse gases and cancer detection.

Sensors are a constant feature of our everyday lives. Although they often go unperceived, sensors provide critical information essential to modern healthcare, security, and environmental monitoring. Modern cars alone contain over 100 sensors and this number will only increase.

Quantum sensing is poised to revolutionize today's sensors, significantly boosting the performance they can achieve. More precise, faster, and reliable measurements of physical quantities can have a transformative effect on every area of science and technology, including our daily lives.

However, the majority of quantum sensing schemes rely on special entangled or squeezed states of light or matter that are hard to generate and detect. This is a major obstacle to harnessing the full power of quantum-limited sensors and deploying them in real-world scenarios.

Finding coherence in quantum chaos

A theoretical breakthrough in understanding quantum chaos could open new paths into researching quantum information and quantum computing, many-body physics, black holes, and the still-elusive quantum to classical transition.

“By applying balanced energy gain and loss to an open quantum system, we found a way to overcome a previously held limitation that assumed interactions with the surrounding environment would decrease quantum chaos,” said Avadh Saxena, a theoretical physicist at Los Alamos National Laboratory and member of the team that published the paper on quantum chaos in Physical Review Letters. “This discovery points to new directions in studying quantum simulations and quantum information theory.”

Quantum chaos differs from classical-physics chaos theory. The latter seeks to understand deterministic, or non-random, patterns and systems that are highly sensitive to initial conditions. The so-called butterfly effect is the most familiar example, whereby the flap of a butterfly’s wings in Texas could, through a bewilderingly complicated but not random chain of cause and effect, lead to a tornado in Kansas.

On the other hand, quantum chaos describes chaotic classical dynamical systems in terms of quantum theory. Quantum chaos is responsible for the scrambling of information occurring in complex systems such as blackholes. It reveals itself in the energy spectra of the system, in the form of correlations between its characteristic modes and frequencies.

It has been believed that as a quantum system loses coherence, or its “quantumness,” by coupling to the environment outside the system—the so-called quantum to classical transition—the signatures of quantum chaos are suppressed. That means they can’t be exploited as quantum information or as a state that can be manipulated.

‘Beam Me Up:’ Nation’s First Quantum Drone Provides Unrivaled Security

Hacked bank and Twitter accounts, malicious power outages and attempts to tamper with medical records threaten the security of the nation’s health, money, energy, society and infrastructure. Harnessing the laws of nature – namely quantum physics – cutting–edge teleportation technology is taking cybersecurity to new, “unhackable” heights using miniscule particles of light or “beams.”

Florida Atlantic University’s Warner A. Miller, Ph.D., in concert with Qubitekk and L3Harris, is leading the United States’ efforts to deliver the first drone-based, mobile quantum network to seamlessly maneuver around buildings, inclement weather and terrain and quickly adapt to changing environments such as warfare.

Together with Qubitekk, an award-winning leader in manufacturing entangled photon sources and other hardware for networking quantum processors and sensors, FAU has been entrusted by the U.S. Office of the Secretary of Defense to develop the project.

The network includes a ground station, drones, lasers and iber optics to share quantum-secured information. Today’s telecommunication networks use fiber optics, connected by laser beams from the ground and between planes and satellites — called fiber and free space optical networks. Drones are used to save lives, secure infrastructure, help the environment and thwart hostile military advances such as the war between Russia and Ukraine.

New tool measures atomic scale defects, identifies transistor limitations

Engineering science and mechanics doctoral student Fedor Sharov adjusts settings in a very low frequency EDMR spectrometer.
Credit: Kelby Hochreither/Penn State

A new technique for studying defects in semiconductor materials could lead to improved speed, power and performance of electronic devices by revealing the atomic-level limitations of advanced materials.

Developed by a Penn State-led team of researchers and lead by former Penn State graduate student James Ashton, the analytic tool makes use of extremely small magnetic fields and frequencies far smaller than those typically used in such measurements to detect and measure imperfections in new materials, providing structural information about the magnetic interactions between electrons and nearby magnetic nuclei in a simpler way than previously possible.

The approach was published as a cover article in Applied Physics Letters. According to Patrick Lenahan, distinguished professor of engineering science and mechanics at Penn State and Ashton’s doctoral thesis adviser, the tool allows researchers to take a big step toward solving a variety of faults in next-generation devices.

Spinning is key for line-dancing electrons in iron selenide

Quantum physicists Pengcheng Dai (left) and Qimiao Si outside Rice’s Brockman Hall for Physics in November 2021.
Photo by Jeff Fitlow/Rice University

Rice University quantum physicists are part of an international team that has answered a puzzling question at the forefront of research into iron-based superconductors: Why do electrons in iron selenide dance to a different tune when they move right and left rather than forward and back?

A research team led by Xingye Lu at Beijing Normal University, Pengcheng Dai at Rice and Thorsten Schmitt at the Paul Scherrer Institute (PSI) in Switzerland used resonant inelastic X-ray scattering (RIXS) to measure the behavior of electron spins in iron selenide at high energy levels.

Spin is the property of electrons related to magnetism, and the researchers discovered spins in iron selenide begin behaving in a directionally dependent way at the same time the material begins exhibiting directionally dependent electronic behavior, or nematicity. The team’s results were published online this week in Nature Physics.

Research breakthrough means warp speed ‘Unruh effect’ can finally be tested in lab settings

SFLORG Stock image

A major hurdle for work at the forefront of fundamental physics is the inability to test cutting-edge theories in a laboratory setting. But a recent discovery opens the door for scientists to see ideas in action that were previously only understood in theory or represented in science fiction.

One such theory is on the Unruh effect. When astronauts in a spacecraft undergo super strong acceleration and see the light of stars stream by, then the Unruh effect is an additional warm glow on top of the streaming light. First predicted by Canadian physicist Bill Unruh, this effect is closely related to the glow from black holes predicted by Stephen Hawking. This is because black holes strongly accelerate everything towards them.

“Black holes are believed to be not entirely black,” says Barbara Šoda, a PhD student in physics at the University of Waterloo. “Instead, as Stephen Hawking discovered, black holes should emit radiation. This is because, while nothing else can escape a black hole, quantum fluctuations of radiation can.”

Similar to how the Hawking effect needs a black hole, the Unruh effect requires enormous accelerations to produce a significant glow. The Unruh effect was therefore thought to be so weak that it would be impossible to measure with the acceleration that can be achieved in experiments with current technology.

Hidden Distortions Trigger Promising Thermoelectric Property

Brookhaven Lab members of the research team: Simon Billinge, Milinda Abeykoon, and Emil Bozin adjust instruments for data collection at the Pair Distribution Function beamline of the National Synchrotron Light Source II. In this setup, a stream of hot air heats samples with degree-by-degree precision as x-rays collect data on how the material changes.
Credit: Brookhaven National Laboratory

In a world of materials that normally expand upon heating, one that shrinks along one 3D axis while expanding along another stands out. That’s especially true when the unusual shrinkage is linked to a property important for thermoelectric devices, which convert heat to electricity or electricity to heat.

In a paper just published in the journal Advanced Materials, a team of scientists from Northwestern University and the U.S. Department of Energy’s Brookhaven National Laboratory describe the previously hidden sub-nanoscale origins of both the unusual shrinkage and the exceptional thermoelectric properties in this material, silver gallium telluride (AgGaTe2). The discovery reveals a quantum mechanical twist on what drives the emergence of these properties—and opens up a completely new direction for searching for new high-performance thermoelectrics.

Researchers Create Self-Assembled Logic Circuits from Proteins

In a proof-of-concept study, researchers have created self-assembled, protein-based circuits that can perform simple logic functions. The work demonstrates that it is possible to create stable digital circuits that take advantage of an electron’s properties at quantum scales.

One of the stumbling blocks in creating molecular circuits is that as the circuit size decreases the circuits become unreliable. This is because the electrons needed to create current behave like waves, not particles, at the quantum scale. For example, on a circuit with two wires that are one nanometer apart, the electron can “tunnel” between the two wires and effectively be in both places simultaneously, making it difficult to control the direction of the current. Molecular circuits can mitigate these problems, but single-molecule junctions are short-lived or low-yielding due to challenges associated with fabricating electrodes at that scale.

“Our goal was to try and create a molecular circuit that uses tunneling to our advantage, rather than fighting against it,” says Ryan Chiechi, associate professor of chemistry at North Carolina State University and co-corresponding author of a paper describing the work.

Fermilab engineers develop new control electronics for quantum computers that improve performance and cut costs

Gustavo Cancelo led a team of Fermilab engineers to create a new compact electronics board: It has the capabilities of an entire rack of equipment that is compatible with many designs of superconducting qubits at a fraction of the cost.
Photo: Ryan Postel, Fermilab

When designing a next-generation quantum computer, a surprisingly large problem is bridging the communication gap between the classical and quantum worlds. Such computers need specialized control and readout electronics to translate back and forth between the human operator and the quantum computer’s languages — but existing systems are cumbersome and expensive.

However, a new system of control and readout electronics, known as Quantum Instrumentation Control Kit, or QICK, developed by engineers at the U.S. Department of Energy’s Fermi National Accelerator Laboratory, has proved to drastically improve quantum computer performance while cutting the cost of control equipment.

“The development of the Quantum Instrumentation Control Kit is an excellent example of U.S. investment in joint quantum technology research with partnerships between industry, academia and government to accelerate pre-competitive quantum research and development technologies,” said Harriet Kung, DOE deputy director for science programs for the Office of Science and acting associate director of science for high-energy physics.

Quantum teleportation: the express lane for quantum data traffic

An artist’s conception of an error-correction protocol: the photons affected by environment are fixed then used to carry the data teleported into them.
Credit: Maria Slussarenko

Teleportation may be a concept usually reserved for science fiction, but researchers have demonstrated that it can be used to avoid loss in communication channels on the quantum level.

The team, including researchers from Griffith University’s Centre for Quantum Dynamics, has highlighted the issues around inherent loss that occurs across every form of communication channel (for example, internet or phone) and discovered a mechanism that can reduce that loss.

Dr Sergei Slussarenko
from the Centre of Quantum Dynamics.

Professor Geoff Pryde, Dr Sergei Slussarenko, Dr Sacha Kocsis and Dr Morgan Weston, and researchers from The University of Queensland and the National Institute of Standards and Technology, say the finding is an important step towards implementing ‘quantum internet’, which will bring unprecedented capabilities not accessible with today’s web.

Dr Slussarenko said the study was the first to demonstrate an error reduction method that improved the performance of a channel.

“First, we looked at the raw data transmitted via our channel and could see a better signal with our method, than without it,” he said.

“In our experiment, we first sent a photon through the loss – this photon is not carrying any useful information so losing it was not a big problem.

In the race to build quantum computing hardware, silicon begins to shine

Silicon-based device in development for use in quantum computers. Gate electrodes shown in blue, red, and green are used to define the quantum dot potentials while the micromagnet on top provides a magnetic field gradient. The image was taken using scanning electron microscopy and the colors were applied for clarity. 
Image credit: Adam Mills, Princeton University

Research conducted by Princeton University physicists is paving the way for the use of silicon-based technologies in quantum computing, especially as quantum bits – the basic units of quantum computers. This research promises to accelerate the use of silicon technology as a viable alternative to other quantum computing technologies, such as superconductors or trapped ions.

In research published in the journal Science Advances, Princeton physicists used a two-qubit silicon quantum device to achieve an unprecedented level of fidelity. At above 99 percent, this is the highest fidelity thus far achieved for a two-qubit gate in a semiconductor and is on par with the best results achieved by competing technologies. Fidelity, which is a measure of a qubit’s ability to perform error-free operations, is a key feature in the quest to develop practical and efficient quantum computing.

Researchers around the world are trying to figure out which technologies — such as superconducting qubits, trapped ions or silicon spin qubits, for example — can best be employed as the basic units of quantum computing. And, equally significant researchers are exploring which technologies will have the ability to scale up most efficiently for commercial use.

“Silicon spin qubits are gaining momentum [in the field],” said Adam Mills, a graduate student in the Department of Physics at Princeton University and the lead author of the recently published study. “It’s looking like a big year for silicon overall.”

New spin lasers for ultra-fast data transfer

Martin Hofmann receives funding as part of a Reinhart-Koselleck project for the development of spin lasers.
Credit: RUB, Marquard

The conventional type of Internet data transmission soon reaches fundamental physical limits. The process can only become faster if you rely on a different principle. Bochum researchers do that.

The transfer of data today is based on light pulses that are sent through fiber optic cables. The faster the light intensity varies, the faster you can transfer information. However, fundamental physical limits of the lasers that generate the modulated light prevent the process from becoming much faster than it is currently. The team led by Prof. Dr. Martin Hofmann, chair of photonics and terahertz technology at the Ruhr University Bochum. With the help of spin lasers, the researchers want to encode information in the polarization of light instead of in light intensity. The German Research Foundation will support the work in the future as part of a Reinhart-Koselleck project with 1.25 million euros for five years.

Discovery of Matter-Wave Polaritons Sheds New Light on Photonic Quantum Technologies

An artistic rendering of the research findings in the polariton study shows the atoms in an optical lattice forming an insulating phase (left); atoms turning into matter-wave polaritons via vacuum coupling mediated by microwave radiation represented by the green color (center); polaritons becoming mobile and forming a superfluid phase for strong vacuum coupling (right).
Photo Credit: Alfonso Lanuza/Schneble Lab/Stony Brook University.

The development of experimental platforms that advance the field of quantum science and technology (QIST) comes with a unique set of advantages and challenges common to any emergent technology. Researchers at Stony Brook University, led by Dominik Schneble, PhD, report the formation of matter-wave polaritons in an optical lattice, an experimental discovery that enables studies of a central QIST paradigm through direct quantum simulation using ultracold atoms. The researchers project that their novel quasiparticles, which mimic strongly interacting photons in materials and devices but circumvent some of the inherent challenges, will benefit the further development of QIST platforms that are poised to transform computing and communication technology.

The findings are detailed in a paper published in Nature Physics.

The research sheds light on fundamental polariton properties and related many-body phenomena, and it opens up novel possibilities for studies of polaritonic quantum matter.

An important challenge in work with photon-based QIST platforms is that while photons can be ideal carriers of quantum information they do not normally interact with each other. The absence of such interactions also inhibits the controlled exchange of quantum information between them. Scientists have found a way around this by coupling the photons to heavier excitations in materials, thus forming polaritons, chimera-like hybrids between light and matter. Collisions between these heavier quasiparticles then make it possible for the photons to effectively interact. This can enable the implementation of photon-based quantum gate operations and eventually of an entire QIST infrastructure.

Micro­cavities as a sensor plat­form

Nano particles trapped between mirrors might be a promising platform for quantum sensors.
Credit: IQOQI Innsbruck

Sensors are a pillar of the Internet of Things, providing the data to control all sorts of objects. Here, precision is essential, and this is where quantum technologies could make a difference. Researchers in Innsbruck and Zurich are now demonstrating how nanoparticles in tiny optical resonators can be transferred into quantum regime and used as high-precision sensors.

Advances in quantum physics offer new opportunities to significantly improve the precision of sensors and thus enable new technologies. A team led by Oriol Romero-Isart of the Institute of Quantum Optics and Quantum Information at the Austrian Academy of Sciences and the Department of Theoretical Physics at the University of Innsbruck and a team lead by Romain Quidant of ETH Zurich are now proposing a new concept for a high-precision quantum sensor. The researchers suggest that the motional fluctuations of a nanoparticle trapped in a microscopic optical resonator could be reduced significantly below the zero-point motion, by exploiting the fast unstable dynamics of the system.

Let quantum dots grow regularly

With this experimental setup, the researchers check the quality of the quantum dots. Green laser light is used to stimulate the quantum dots that then emit infrared light.
© İsmail Bölükbaşı

With the previous manufacturing process, the density of the structures was difficult to control. Now researchers can create a kind of checkerboard pattern. A step towards application, for example in a quantum computer.

Quantum points could one day form the basic information units of quantum computers. Researchers at the Ruhr University Bochum (RUB) and the Technical University of Munich (TUM) have significantly improved the manufacturing process for these tiny semiconductor structures, together with colleagues from Copenhagen and Basel. The quantum dots are generated on a wafer, a thin semiconductor crystal disc. So far, the density of the structures on it has been difficult to control. Now scientists can create specific arrangements - an important step towards an applicable component that should have a large number of quantum dots.

The team published the results on 28. March 2022 in the journal Nature Communications. A group led by Nikolai Bart, Prof. Dr. Andreas Wieck and Dr. Arne Ludwig from the RUB Chair for Applied Solid State Physics with the team around Christian Dangel and Prof. Dr. Jonathan Finley from the TUM working group semiconductor nanostructures and quantum systems as well as with colleagues from the universities of Copenhagen and Basel.

Quantum Physics Sets a Speed Limit to Electronics

An ultra-short laser pulse (blue) creates free charge carriers, another pulse (red) accelerates them in opposite directions.
Credit: Vienna University of Technology

Semiconductor electronics is getting faster and faster - but at some point, physics no longer permits any increase. The shortest possible time scale of optoelectronic phenomena has now been investigated.

How fast can electronics be? When computer chips work with ever shorter signals and time intervals, at some point they come up against physical limits. The quantum-mechanical processes that enable the generation of electric current in a semiconductor material take a certain amount of time. This puts a limit to the speed of signal generation and signal transmission.

TU Wien (Vienna), TU Graz and the Max Planck Institute of Quantum Optics in Garching have now been able to explore these limits: The speed can definitely not be increased beyond one petahertz (one million gigahertz), even if the material is excited in an optimal way with laser pulses. This result has now been published in the scientific journal "Nature Communications".