Physics News and Discussions

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Putting a new spin on 1T phase tantalum disulfide: Scientists uncover a hidden electronic state
https://phys.org/news/2024-03-1t-phase- ... tists.html
by Denise Yazak, Brookhaven National Laboratory

Research often unfolds as a multistage process. The solution to one question can spark several more, inspiring scientists to reach further and look at the larger problem from several different perspectives. Such projects can often be the catalyst for collaborations that leverage the expertise and capabilities of different teams and institutions as they grow.

For half a century, scientists have delved into the mysteries of 1T phase tantalum disulfide (1T-TaS2), an inorganic layered material with some intriguing quantum properties, like superconductivity and charge density waves (CDW).

To unlock the complex structure and behavior of this material, researchers from the Jozef Stefan Institute in Slovenia and Université Paris-Saclay in France reached out to experts utilizing the Pair Distribution Function (PDF) beamline at the National Synchrotron Light Source II (NSLS-II), a U.S. Department of Energy (DOE) Office of Science User Facility located at DOE's Brookhaven National Laboratory, to learn more about the material's structure.

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Cern: Scientists search for mysterious ghost particles

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Some physicists have long suspected that mysterious 'ghost' particles in the world around us could greatly advance our understanding of the true nature of the Universe.

Now scientists think they've found a way to prove whether or not they exist.

Europe's centre for particle research, Cern, has approved an experiment designed to find evidence for them.

The new instrument will be a thousand times more sensitive to such particles than previous devices.

It will smash particles into a hard surface to detect them instead of against each other like Cern's main device the Large Hadron Collider (LHC).

https://www.bbc.co.uk/news/science-environment-68631692

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The world is one step closer to secure quantum communication on a global scale
https://phys.org/news/2024-03-world-clo ... lobal.html
by University of Waterloo

Researchers at the University of Waterloo's Institute for Quantum Computing (IQC) have brought together two Nobel prize-winning research concepts to advance the field of quantum communication.

Scientists can now efficiently produce nearly perfect entangled photon pairs from quantum dot sources. The research, "Oscillating photonic Bell state from a semiconductor quantum dot for quantum key distribution," was published in Communications Physics

Entangled photons are particles of light that remain connected, even across large distances, and the 2022 Nobel Prize in Physics recognized experiments on this topic. Combining entanglement with quantum dots, a technology recognized with the Nobel Prize in Chemistry in 2023, the IQC research team aimed to optimize the process for creating entangled photons, which have a wide variety of applications, including secure communications.

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First observation of photons-to-taus in proton–proton collisions
https://phys.org/news/2024-03-photons-t ... sions.html
by CERN

In March 2024, the CMS collaboration announced the observation of two photons creating two tau leptons in proton–proton collisions. It is the first time that this process has been seen in proton–proton collisions, which was made possible by using the precise tracking capabilities of the CMS detector. It is also the most precise measurement of the tau's anomalous magnetic moment and offers a new way to constrain the existence of new physics.

The tau, sometimes called tauon, is a peculiar particle in the family of leptons. In general, leptons, together with quarks, make up the "matter" content of the Standard Model (SM). The tau was only discovered in the late 1970s at SLAC, and its associated neutrino—the tau neutrino—completed the tangible matter part upon its discovery in 2000 by the DONUT collaboration at Fermilab.

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Unlocking visible femtosecond fiber oscillators: An advance in laser science
https://phys.org/news/2024-03-visible-f ... vance.html
by SPIE

The emergence of ultrafast laser pulse generation, marking a significant milestone in laser science, has triggered incredible progress across a wide array of disciplines, encompassing industrial applications, energy technologies, life sciences, and beyond. Among the various laser platforms that have been developed, fiber femtosecond oscillators, esteemed for their compact design, outstanding performance and cost-effectiveness have become one of the mainstream technologies for femtosecond pulse generation.

However, their operating wavelengths are predominantly limited to the infrared region, spanning from of 0.9-3.5 μm, which has, in turn, restricted their applicability in numerous applications that require light sources at visible wavelengths (390-780 nm). Expanding compact femtosecond fiber oscillators into new visible wavelengths has long been a challenging yet fervently pursued goal in laser science.

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Romania center explores world's most powerful laser
https://phys.org/news/2024-03-romania-c ... erful.html
by Anne BEADE
The Romania research center houses the world's most powerful laser beam.

"Ready? Signal sent!" In the control room of a research center in Romania, engineer Antonia Toma activates the world's most powerful laser, which promises revolutionary advances in everything from the health sector to space.

The laser at the center, near the Romanian capital Bucharest, is operated by French company Thales, using Nobel prize-winning inventions.

France's Gerard Mourou and Donna Strickland of Canada won the 2018 Nobel Physics Prize for harnessing the power of lasers for advanced precision instruments in corrective eye surgery and in industry.

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Researchers reveal evidence of transition from ergodic toward ergodic breaking dynamics
https://phys.org/news/2024-04-reveal-ev ... amics.html
by University of Science and Technology of China

A collaborative research team has reported experimental evidence of a transition from ergodic toward ergodic breaking dynamics in driven-dissipative Rydberg atomic gases. The results were published in Science Advances.

Many-body systems often relax to an equilibrium state because of ergodicity, such that an observable becomes invariant with time. In the case of robust equilibrium, the observable rapidly seeks new fixed points in phase space. However, there are exceptions, for example, in integrable and many-body localized systems, where broken ergodicity can inhibit system equilibrium and thermalization.

The study of ergodic breaking is instructive for market collapse and recovery in finance, brain epilepsy in neural networks, and early warning of critical leaps in complex systems. Rydberg atoms with long-range interactions serve as ideal many-body systems to study nonergodic many-body dynamics. In a system of driven-dissipative Rydberg atoms, the system will have a non-equilibrium long-time phase oscillation due to the aggregation of Rydberg atoms.

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100 kilometers of quantum-encrypted transfer
https://phys.org/news/2024-04-kilometer ... ypted.html
by Technical University of Denmark

Researchers at DTU have successfully distributed a quantum-secure key using a method called continuous variable quantum key distribution (CV QKD). The researchers have managed to make the method work over a record 100 km distance—the longest distance ever achieved using the CV QKD method. The advantage of the method is that it can be applied to the existing Internet infrastructure.

Quantum computers threaten existing algorithm-based encryptions, which currently secure data transfers against eavesdropping and surveillance. They are not yet powerful enough to break them, but it's a matter of time. If a quantum computer succeeds in figuring out the most secure algorithms, it leaves an open door to all data connected via the internet. This has accelerated the development of a new encryption method based on the principles of quantum physics.

But to succeed, researchers must overcome one of the challenges of quantum mechanics—ensuring consistency over longer distances. Continuous variable quantum key distribution has so far worked best over short distances.

"We have achieved a wide range of improvements, especially regarding the loss of photons along the way. In this experiment, published in Science Advances, we securely distributed a quantum-encrypted key 100 kilometers via fiber optic cable. This is a record distance with this method," says Tobias Gehring, an associate professor at DTU, who, together with a group of researchers at DTU, aims to be able to distribute quantum-encrypted information around the world via the internet.

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I got into this theory from the TV series Sliders and went from there, the only problem is that I now think like this now.

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Quantum crystal of frozen electrons—the Wigner crystal—is visualized for the first time
https://phys.org/news/2024-04-quantum-c ... igner.html
by Princeton University

Electrons—the infinitesimally small particles that are known to zip around atoms—continue to amaze scientists despite the more than a century that scientists have studied them. Now, physicists at Princeton University have pushed the boundaries of our understanding of these minute particles by visualizing, for the first time, direct evidence for what is known as the Wigner crystal—a strange kind of matter that is made entirely of electrons.

The finding, published in Nature, confirms a 90-year-old theory that electrons can assemble into a crystal-like formation of their own, without the need to coalesce around atoms. The research could help lead to the discovery of new quantum phases of matter when electrons behave collectively.

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Physicists discover a novel quantum state in an elemental solid
https://phys.org/news/2024-04-physicist ... solid.html
by Princeton University

Physicists have observed a novel quantum effect termed "hybrid topology" in a crystalline material. This finding opens up a new range of possibilities for the development of efficient materials and technologies for next-generation quantum science and engineering.

The finding, published in Nature, came when Princeton scientists discovered that an elemental solid crystal made of arsenic (As) atoms hosts a never-before-observed form of topological quantum behavior. They were able to explore and image this novel quantum state using a scanning tunneling microscope (STM) and photoemission spectroscopy, the latter a technique used to determine the relative energy of electrons in molecules and atoms.

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Evidence of a new subatomic particle observed
https://phys.org/news/2024-04-evidence- ... ticle.html
by Chinese Academy of Sciences

The BESIII collaboration have reported the observation of an anomalous line shape around ppbar mass threshold in the J/ψ→γ3(π+π-) decay, which indicates the existence of a ppbar bound state. The paper was published online in Physical Review Letters.

The proximity in mass to 2mp is suggestive of nucleon-antinucleon bound states, an idea that has a long history. Before the birth of Quark Model, a nucleon-antinucleon bound state was already proposed by Prof. E. Fermi and Prof. C. N. Yang.

There is an accumulation of evidence for anomalous behavior in the proton-antiproton system near the ppbar mass threshold, e.g., J/ψ→γppabr , J/ψ→γπ+π-η' and the proton's effective form factor determined from e+e-→ppbar, exhibiting a narrow peak or a very steep falloff around the ppbar mass threshold, which inspired many speculations and renewed the interests on the nucleon-antinucleon bound state.

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Combating disruptive 'noise' in quantum communication
https://phys.org/news/2024-04-combating ... ation.html
by Griffith University

In a significant milestone for quantum communication technology, an experiment has demonstrated how networks can be leveraged to combat disruptive 'noise' in quantum communications.

The international effort led by researchers from Griffith University's Center for Quantum Dynamics highlights the potential of quantum networks in revolutionizing communication technologies on a quantum level. The study, "Nonlocality activation in a photonic quantum network," has been published in Nature Communications.

Researchers Dr. Nora Tischler and Dr. Sergei Slussarenko, program managers at the ARC Center of Excellence for Quantum Computation and Communication Technology (CQC2T) node at Griffith University, believe their findings are a first step towards large-scale quantum networks, which may fundamentally change how we communicate on a global scale.