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Femtosecond nano-imaging reveals ultrafast optical control of phonon polaritons

A collaborative research team has successfully visualized in real space the ultrafast optical modulation of hyperbolic phonon polaritons (HPhPs) in a van der Waals heterostructure composed of hBN and WS2. The research is published in the journal Nano Letters, and was led by Kazuki Kamada of the Institute for Molecular Science (IMS) and Osaka Metropolitan University, along with Dr. Jun Nishida, assistant professor at IMS, and Takashi Kumagai, associate professor at IMS.

HPhPs are hybrid light-matter modes formed through strong coupling between infrared electromagnetic fields and optical phonons in a material. Their hybrid character allows them to coherently transport electromagnetic energy while confining it to spatial scales far below the wavelength of light in free space. These properties make HPhPs promising for nanoscale light manipulation, high-sensitivity spectroscopy and future nanophotonic technologies. Dynamically controlling HPhPs at ultrafast speeds could provide an important foundation for active nanoscale optical devices.

Organic crystal reveals how Joule heating stabilizes resistive switching

Metal-insulator transitions (MITs), in which a material changes from a metallic state with low resistivity to an insulating state because of a change in an external parameter, such as temperature, pressure or an electric field, are a central topic in fundamental physics research.

In materials that undergo MITs, it has also been observed that in the insulating phase, but near the transition point, applying an electric field or current can sometimes trigger a sudden drop in resistance, known as resistive switching.

This volatile resistive switching holds promise for various applications, including resistive memory, optoelectronics and neuromorphic computing, which is key to artificial intelligence implementation.

Physicists take Hall effect in a new direction

Carnegie Mellon University scientists have uncovered a new phenomenon that challenges a longstanding assumption about how electronic materials respond to magnetic fields. The discovery broadens the fundamental understanding of the Hall effect, a principle widely used to measure the magnetic and electronic properties of materials.

Published in Nature Materials, the research could lay the groundwork for simpler, more versatile magnetic sensing technologies used in electronics, transportation and medical imaging.

The Hall effect has been a key tool for studying material properties for more than a century. In 1879, Edwin Hall showed that applying a magnetic field perpendicular to a material deflects moving charges, producing a measurable voltage. By analyzing this signal, scientists can determine whether electric current is carried by negative or positive charges, how many of those charges are moving through the material and how easily they flow.

Hollow-core fiber platform could help different quantum technologies connect

Quantum technologies promise secure communication networks, powerful forms of computing and new sensing tools. One of the major challenges, however, is that different quantum systems often operate at different wavelengths of light. Quantum memories, trapped ions and other quantum devices may work best in the ultraviolet or visible range, while long-distance communication over optical fibers works most efficiently at telecommunications wavelengths.

Building practical quantum networks will require reliable ways to translate quantum information between these different optical bands without losing the information carried by the light.

A new study published in Advanced Photonics Nexus explores a promising route to achieving that goal through a process known as four-wave mixing (FWM).

Scientists Discover a Brain Signal Linked to Severe Suicidal Thoughts

P2RX7 may be linked to severe suicidal thoughts and recovery, but researchers still need to confirm the pattern in living people.

Severe suicidal thoughts may leave a detectable biological signal in the brain, and that signal could also change when people recover. Researchers at the Netherlands Institute for Neuroscience have identified a receptor that may be linked to these shifts, providing a possible new direction for studying resilience and suicide prevention.

In the Netherlands, nearly five people die by suicide each day, and there may be about twenty suicide attempts for every death. Despite the enormous consequences for individuals and families, scientists still understand relatively little about the biological processes associated with suicidal thoughts. Effective medications specifically targeting suicidal thoughts are also urgently needed.

A Major Quantum Computing Problem May Finally Have an Answer: Can We Trust the Results?

Researchers can now put numerical error limits on quantum simulations, showing how much confidence to place in their results.

As quantum simulators become powerful enough to tackle problems beyond the reach of conventional computers, a difficult question follows: how can researchers know whether their answers are accurate? When classical calculations are still possible, the two approaches can be compared directly. Once quantum systems move beyond that point, however, scientists need another way to verify the results.

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 demonstrated a method for experimentally characterizing a quantum simulator and turning its uncertainties into numerical error limits. A team led by Manoj Joshi and Christian Roos tested the approach with an ion-trap quantum simulator containing as many as 51 ions.

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