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Category: quantum physics – Page 4

Dark energy and quantum gravity may be deeply intertwined

For close to a century, physicists have pursued a way to unite gravity with quantum mechanics. Known as quantum gravity, this goal has remained frustratingly out of reach so far. Similarly elusive is the force of dark energy, which is believed to be driving the universe’s accelerating expansion.

But through new research published in Physical Review D, physicist Savvas Koushiappas of Brown University has proposed a new explanation suggesting that these two phenomena might not be separate at all. Instead, dark energy could be a natural side effect of quantum gravity, acting on the geometry of space itself.

New measurements explain how silicon and diamond achieve extreme reversible stretching

A research team led by Yang Lu from the Department of Mechanical Engineering at the Faculty of Engineering, The University of Hong Kong (HKU), has uncovered the microscopic physical nature of ultralarge elasticity in covalent semiconductors such as silicon and diamond. The discovery provides quantitative guidance for deep elastic strain engineering (DESE), paving the way for the development of next-generation electronic, optoelectronic and quantum devices.

Despite the potential of DESE, the underlying deformation mechanisms of these covalent crystals have long remained elusive. The research team was the first to directly observe the pure lattice evolution of single-crystal silicon and diamond under tension at the atomic scale.

By precisely quantifying the resulting lattice strains, the researchers bridged macroscopic mechanical strain with microscopic lattice strain, establishing a physical foundation for the design of advanced semiconductor devices. The research team also includes PhD student Jiayi Li and postdoctoral fellow Dr. Heyi Wang.

Intense light bent out of shape—ultrafast lenses made from gas

Researchers from the MPIK in Heidelberg used an atomic gas as a time-dependent lens to shape and spectrally manipulate intense high-frequency laser pulses. This gas-based optical element could pave the way toward better XUV- and X-ray pulse control for applications such as chemical reaction steering, quantum computing, and advanced spectroscopy methods for fundamental science. The paper is published in the journal Science Advances.

Magnetically levitated quantum bit could address design flaws

Researchers at the FAMU-FSU College of Engineering and the National High Magnetic Field Laboratory, headquartered at Florida State University, have designed a new quantum computing architecture that uses magnetic levitation to smooth over design flaws in the intricate components necessary to run a quantum computer.

Quantum bits, or qubits, can be as small as a few nanometers, and manufacturing them inevitably introduces random flaws on their surfaces. By using superconducting magnets to levitate neon particles, the research addresses a challenge in electron-on-neon qubit devices: the tendency for electrons to become trapped by tiny random bumps on the neon surface, making them function unpredictably.

The study, published in PRX Quantum, could help pave the way for more reproducible and scalable quantum computing technologies.

Quantum Fluctuations Break a Crystal’s Symmetry Rules

Electronic fluctuations can act as a resonant bridge between normally separate crystal vibrations, offering a new route to study and control ferroaxial quantum states.

Symmetry is a basic rule of the natural world. It explains why some objects appear the same after they are rotated, reflected, or changed in other ways. In materials, symmetry helps determine how atoms and electrons are positioned and how they move together. It can also block certain collective atomic motions (vibrations) from interacting, meaning some motions are normally unable to influence one another. But a new study asks whether those limits are always fixed.

A study published in Nature Physics suggests that some of these restrictions can be loosened. Researchers from the University of Texas at Austin and the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg found that electronic fluctuations can create a dynamic connection between vibrations that symmetry would usually keep apart. Led by Edoardo Baldini’s group at UT Austin, the work shows how light, vibrations, and electrons can become linked inside a ferroaxial crystal, a special material that may offer new ways to control quantum states with light.

Universal pattern revealed in quantum matter

When different materials transition from one phase to another, such as water coming to a boil or a magnet losing its ability to attract metals, something remarkable can happen: They begin to behave identically, following the same mathematical rules. “Physicists call this trait universality—the messy, microscopic details wash out and only a few essential features survive,” explains Jason Alicea, William K. Davis Professor of Theoretical Physics. The math underlying these universal traits is commonly described by a theoretical framework called conformal field theory.

Reporting in the journal Nature, a collaboration between the experimental group of Caltech’s Manuel Endres, professor of physics, and Alicea’s theory group, together with theorists at Université Paris-Saclay and the Technical University of Munich, performed first-of-their-kind experiments on two different conformal field theories using quantum simulators, which are simplified versions of quantum computers tailored for specific tasks.

Using new technology developed for these quantum simulators, the team reports the first direct measurement of energy levels in synthetic quantum matter as predicted by the Ising and tricritical Ising conformal field theories. (Ising refers to Ernst Ising, a physicist who, in the 1920s, solved an early model of magnetism.) Both theories describe universal behavior that emerges when a quantum system—exhibiting exotic traits such as entanglement and superposition—is placed at a tipping point between two states, one of which is more ordered than the other.

Turning a quantum battery’s environmental sensitivity into an advantage

Quantum batteries, devices that store energy by exploiting quantum mechanical phenomena, could, in principle, be charged faster and more efficiently than classical ones. Despite their potential, connecting these batteries to chargers is known to create quantum correlations that can trap some energy inside the combined battery-charger system. This can reduce useful work, or the energy available to complete a task that can be extracted from the battery alone.

Researchers at the University of Insubria & INFN, University of Genova & CNR-SPIN and University of Milan recently proposed a new design strategy that could potentially increase the usable energy of quantum batteries. Their approach, outlined in a paper in Physical Review Letters, involves connecting both a battery and its charger to a shared environment that is continuously monitored.

“Quantum technologies—including quantum batteries—are usually designed under the assumption that the environment is the enemy,” the authors told Phys.org.

Supramolecular nanofibers paired with nanohole substrate improve exciton transport in organic solid

Self-assembling, anthracene-based supramolecular nanofibers can enable excitons to migrate hundreds of nanometers, according to a new experimental finding by researchers at Science Tokyo. Coupling these nanofibers with a plasmonic gold nanohole substrate further doubles exciton diffusivity. By mitigating the limited diffusivity of singlet excitons in organic semiconductors, this approach offers a new strategy for improving optoelectronic technologies.

For decades, one of the biggest challenges in organic optoelectronics has been the limited diffusivity of excitons. Created when light is absorbed, excitons diffuse through the semiconducting material before they can dissociate into free charge carriers to generate electricity. However, excitons in conventional organic semiconductors typically diffuse only up to 5–20 nm before recombining, limiting the performance of optoelectronic devices.

Now, researchers from the Institute of Science Tokyo (Science Tokyo) in Japan have managed to overcome this long-standing limitation by combining molecular self-assembly with plasmonic nanotechnology. The breakthrough comes from a study conducted by a collaborative research team comprising Professor Martin Vacha and Associate Professor Yoshimitsu Sagara from Science Tokyo and Dr. Takatoshi Fujita from the National Institute for Quantum Science and Technology in Japan. The findings are published in the journal Nano Letters.

Quantum simulators gain quantitative error bars in 51-ion test

In the coming years, increasingly larger and more powerful quantum systems are expected to tackle problems that are difficult or impossible to solve using conventional computers. However, the more powerful quantum simulations become, the more difficult it is to independently verify their results. Where classical simulation is still feasible, results can be cross-checked directly; beyond that regime, other methods are needed.

Researchers led by Tristan Kraft of the Technical University of Munich and Peter Zoller of the University of Innsbruck and the Institute for Quantum Optics and Quantum Information at the Austrian Academy of Sciences, together with Barbara Kraus of the Technical University of Munich, have now demonstrated how a quantum simulator can be experimentally characterized and how the uncertainties that arise in the process can be translated into quantitative error limits for its results.

The approach was demonstrated by a team led by Manoj Joshi and Christian Roos using an ion-trap quantum simulator containing up to 51 ions.

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