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Category: quantum physics

Ultrafast computing: Light-driven logic tops 10 terahertz in WS₂

The future for our computers will literally be at the speed of light. Extremely short light pulses can perform ultrafast logical operations: these are the findings of a study recently published in the journal Nature Photonics. The study represents an important step toward developing a new generation of information processing technologies, potentially hundreds of times faster than what we have at present.

Today’s computers rely on the movement of electrical charges inside transistors; however, these can only achieve a maximum frequency whose physical limits are hard to overcome. Unlike traditional electronics, based on the movement of electric charges, this innovative approach manipulates the state of electrons in matter by the use of oscillating light.

As Giulio Cerullo of the Politecnico di Milano explained, “We have shown that light can be used not only to transmit information, but also to process it. With the use of ultra-short laser pulses, we can control the quantum states of matter on time scales of a few millionths of a billionth of a second, i.e. at the same frequencies as light oscillations, speeds previously unknown in electronics.” These operations are performed at rates above 10 terahertz, over a hundred times faster than the best modern electronic devices.

Chemical shifts help track molecules breaking apart in real time

When molecules fall apart, their electric charge doesn’t stay put—it rearranges as bonds stretch and break. An international team of scientists has now tracked these ultrafast changes in the small molecule fluoromethane (CH₃F). It was the first time that the Small Quantum Systems (SQS) instrument at European XFEL could deliver detailed insights into transient states during chemical reactions. The research is published in the journal Physical Review X.

These intermediate states, that only exist temporarily while the reaction is ongoing, are often the key drivers of chemistry and therefore crucial to understand. Over the long term, that kind of insight can support progress in areas such as atmospheric science (where sunlight-driven reactions and fragmentation pathways shape air chemistry), as well as the study of complex molecular systems including biomolecules and proteins, where local excitation and charge transfer can trigger structural change.

In the experiment, the researchers first triggered the reaction with an optical laser pulse. Next, they used the X-ray laser pulses that the European XFEL produces, to eject an electron from the core of either the fluorine or the carbon atom in the molecule. They measured the electron’s kinetic energy, which reveals how strongly it was bound inside the atom. That binding energy is extremely sensitive to the local electrical environment, producing so-called “chemical shifts” that act like a fingerprint of the charge distribution surrounding the atom from which the electron has been ejected.

Precisely measuring quantum signals in large spin ensembles

Quantum mechanical effects are known to be easily disrupted by disturbances from the surrounding environment, commonly referred to as noise. To minimize these disturbances, physicists often study these effects in small and carefully controlled systems, in which environmental noise can be minimized.

Researchers at Johns Hopkins University set out to study quantum effects in macroscopic spin ensembles, systems comprised of large numbers of spins (spins is the intrinsic angular momentum of elementary particles). Their paper, published in Nature Physics, introduces a new approach to directly observe quantum spin fluctuations in macroscopic spin ensembles, precisely monitoring their evolution over time.

“Quantum effects are typically observed and exploited in microscopic systems, where individual qubits can be precisely controlled and measured,” Alexander O. Sushkov, senior author of the paper, told Phys.org.

Scientists harness quantum tunneling to boost heavy water production efficiency

A study by scientists at Hunan University introduces a new hydrogen isotope separation method that leverages proton quantum tunneling to produce heavy water, overcoming the key physical limitation faced by current methods that have made the production process difficult and expensive for decades.

According to results published in Proceedings of the National Academy of Sciences, this new strategy achieves a record-high H2O separation factor of 276 at room temperature by designing through-barriers that allow hydrogen nuclei to pass through them via quantum tunneling, leaving deuterium behind.

By leveraging quantum mechanics, the method could pave the way for cleaner and more efficient production of a critical material for future energy technologies.

Scientists control ‘free-flowing’ electric currents with light

By controlling magnetic fields using light, a team of researchers led by NTU scientists has solved a long-standing challenge to precisely direct electric currents produced by quantum materials. Their findings unlock new avenues for controlling the flow of electricity through such materials and could herald the age of energy-efficient quantum computing devices. The research is published in Nature in January.

Like water moving through lakes and rivers, electrons in electric currents encounter resistance when flowing through electronic devices. This resistance generates large amounts of heat, which poses a problem for large computing facilities such as data centers and quantum computers, incurring major costs for cooling.

With artificial intelligence driving the demand for more computing applications, there is a need to produce electricity that flows without resistance to avoid generating excessive amounts of heat. These “free-flowing” electric currents could pave the way for novel low-power electronics and new quantum computing technologies.

Physicists Finally Realize Long-Predicted 2D Topological Crystal in the Lab

Researchers in Finland have experimentally realized a long-predicted class of quantum material: a two-dimensional topological crystalline insulator. Physicists at the University of Jyväskylä and Aalto University (Finland) have successfully created a two-dimensional topological crystalline insulat

In search of a room-temperature superconductor, scientists present a research agenda

The search for materials that can conduct electricity at room temperature without losing energy is one of the greatest and most consequential challenges of modern physics: loss-free power transmission, more efficient motors and generators, more powerful quantum computers, cheaper MRI devices. Hardly any other material discovery has the potential to change so many areas of technology and everyday life at the same time.

An international research team, with the participation of Christoph Heil from the Institute of Theoretical and Computational Physics at Graz University of Technology (TU Graz) is now presenting a systematic approach to finding such materials. In a perspective article in the journal Proceedings of the National Academy of Sciences, a strategy paper that assesses the current state of research and sets out future directions, the 16 authors state that there are no fundamental physical laws that rule out superconductivity at ambient temperature.

Superconductivity controlled by a built-in light-confining cavity

For the first time, physicists have demonstrated that a material’s superconductivity can be altered by coupling it to an in-built, light-confining cavity. In experiments published in Nature, a team led by Itai Keren at Columbia University show how quantum properties can be deliberately engineered by bonding carefully chosen materials together—without applying any external light, pressure, or magnetic field.

As researchers have probed the quantum behavior of solids in ever greater detail, they have uncovered a wealth of so-called “emergent” properties, which arise from intricate interactions between electrons, quantum spins, and localized vibrations of a crystal lattice. Phenomena including superconductivity, magnetism, and charge ordering all emerge from these kinds of collective effects—all richer and more complex than the sum of their microscopic parts.

Building on this principle, physicists are increasingly exploring whether materials could be designed with specific emergent behaviors built directly into their structures. Rather than tuning a compound after it is made, the goal here is to engineer its quantum environment from the outset.

Quantum entanglement offers route to higher-resolution optical astronomy

Researchers in the US have demonstrated how quantum entanglement could be used to detect optical signals from astronomical sources at the single-photon level. Published in Nature, a team led by Pieter-Jan Stas at Harvard University showed how extremely weak light signals could be detected across a fiber link spanning more than 1.5 km—possibly paving the way for optical telescopes with unprecedented resolution.

Interferometry is often used in astronomy to produce high-resolution images of distant objects. By combining light collected across networks of spatially separated detectors, the technique can achieve resolutions comparable to those of a single telescope with a diameter equivalent to the distance between them. In continent-spanning networks like the Event Horizon Telescope, it was used to create the first direct image of a black hole (Messier 87) in 2019.

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