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Category: particle physics – Page 165

Physicists Uncover Unusual New Quantum State Known As “Dirac Spin Liquid”

Researchers at the University of Hong Kong discovered Dirac spinons in the material YCu3-Br, providing evidence of a quantum spin liquid state and potentially advancing applications in quantum computing and high-temperature superconductivity.

Quasiparticles are fascinating entities that arise from collective behavior within materials and can be treated as a group of particles. Specifically, Dirac spinons are anticipated to exhibit unique characteristics similar to Dirac particles in high-energy physics and Dirac electrons in graphene and quantum moiré materials, such as a linear dispersion relation between energy and momentum. However, spin-½ charge-neutral quasiparticles had not been observed in quantum magnets until this work.

‘“To find Dirac spinons in quantum magnets has been the dream of generations of condensed matter physicists; now that we have seen the evidence of them, one can start to think about the countless potential applications of such highly entangled quantum material. Who knows, maybe one-day people will build quantum computers with it, just as people have been doing in the past half-century with silicon,’” said Professor Meng, HKU physicist and one of the corresponding authors of the paper.

More than spins: Exploring uncharted territory in quantum devices

Many of today’s quantum devices rely on collections of qubits, also called spins. These quantum bits have only two energy levels, the ‘0’ and the ‘1’. However, unlike classical bits, qubits can exist in superpositions, meaning they can simultaneously be in a combination of the ‘0’ and ‘1’ states. Spins in real devices also interact with light and vibrations known as bosons, greatly complicating calculations.

In a new publication in Physical Review Letters (“Fast quantum state preparation and bath dynamics using non-Gaussian variational Ansatz and quantum optimal control”), researchers in Amsterdam demonstrate a way to describe spin-boson systems and use this to efficiently configure quantum devices in a desired state.

Quantum devices use the quirky behaviour of quantum particles to perform tasks that go beyond what ‘classical’ machines can do, including quantum computing, simulation, quantum sensing, quantum communication and quantum metrology. These devices can take many forms, such as a collection of superconducting circuits, or a lattice of atoms or ions held in place by lasers or electric fields.

Solar Composition Altered by Plasma Waves

New solar observations indicate that plasma waves are responsible for the Sun’s outer atmosphere having different abundances of chemical elements than the Sun’s other layers.

The solar corona is a halo of hot, tenuous plasma that surrounds the Sun out to large distances. It is visible during solar eclipses (Fig. 1) but is usually outshone by the glare of the Sun’s surface, or photosphere. The corona has different abundances of chemical elements than the rest of the Sun, and a longstanding question has been why this disparity exists. New solar measurements by Mariarita Murabito at the Italian National Institute of Astrophysics (INAF) and colleagues suggest that the difference is caused by plasma waves dragging easily ionized elements from the Sun’s lower atmosphere into the corona [1]. This finding could lead to a better understanding of the structure of stars.

The corona is of great interest to solar physicists, partly because it produces the solar wind—an outflow of hot gas from the Sun. The solar wind is most evident to us on Earth when its particles become trapped in Earth’s magnetic field and collide with our atmosphere, causing an aurora. An important problem in solar physics is to determine which coronal structures generate the solar wind and how solar conditions affect the outflow’s properties. The elemental composition of the solar wind sheds light on its origins, as this composition does not change once the gas leaves the Sun. The solar wind can be directly sampled by spacecraft in situ, and its elemental abundances can be compared to coronal abundances inferred from spectroscopy.

Researchers describe spin-boson systems to configure quantum devices

In a new publication in Physical Review Letters, researchers in Amsterdam demonstrate a way to describe spin-boson systems and use this to efficiently configure in a desired state.

Quantum devices use the quirky behavior of quantum particles to perform tasks that go beyond what “classical” machines can do, including quantum computing, simulation, sensing, communication and metrology. These devices can take many forms, such as a collection of superconducting circuits, or a lattice of atoms or ions held in place by lasers or electric fields.

Regardless of their physical realization, quantum devices are typically described in simplified terms as a collection of interacting two-level or spins. However, these spins also interact with other things in their surroundings, such as light in superconducting circuits or oscillations in the lattice of atoms or ions. Particles of light (photons) and vibrational modes of a lattice (phonons) are examples of bosons.

Neutrons Illuminate the Mysteries of Space Glass

Researchers have developed techniques to manufacture different types of glass in space, uncovering potential for advancements in optical technology.

Thanks to human ingenuity and zero gravity, we reap important benefits from science in space. Consider smartphones with built-in navigation systems and cameras.

Such transformational technologies seem to blend into the rhythm of our everyday lives overnight. But they emerged from years of discoveries and developments of materials that can withstand harsh environments outside our atmosphere. They evolved from decades of laying foundations in basic science to understand how atoms behave in different materials under different conditions.

New theory of gravity solves accelerating universe

The universe is expanding at an accelerating rate but Einstein’s theory of General Relativity and our knowledge of particle physics predict that this shouldn’t be happening. Most cosmologists pin their hopes on Dark Energy to solve the problem. But, as Claudia de Rham argues, Einstein’s theory of gravity is incorrect over cosmic scales, her new theory of Massive Gravity limits gravity’s force in this regime, explains why acceleration is happening, and eliminates the need for Dark Energy.

You can see Claudia de Rham live, debating in ‘Dark Energy and The Universe’ alongside Priya Natarajan and Chris Lintott and ‘Faster Than Light’ with Tim Maudlin and João Magueijo at the upcoming HowTheLightGetsIn Festival on May 24th-27th in Hay-on-Wye.

This article is presented in association with Closer To Truth, an esteemed partner for the 2024 HowTheLightGetsIn Festival.

Quantum entanglement expands to city-sized networks

The delicate nature of quantum information means it does not travel well. A quantum Internet therefore needs devices known as quantum repeaters to swap entanglement between quantum bits, or qubits, at intermediate points. Several researchers have taken steps towards this goal by distributing entanglement between multiple nodes.

In 2020, for example, Xiao-Hui Bao and colleagues in Jian-Wei Pan’s group at the University of Science and Technology of China (USTC) entangled two ensembles of rubidium-87 atoms in vapour cells using photons that had passed down 50 km of commercial optical fibre. Creating a functional quantum repeater is more complex, however: “A lot of these works that talk about distribution over 50,100 or 200 kilometres are just talking about sending out entangled photons, not about interfacing with a fully quantum network at the other side,” explains Can Knaut, a PhD student at Harvard University and a member of the US team.

Quantum tunnels allow particles to break the light-speed barrier

In the fascinating realm of quantum physics, particles seem to defy the laws of classical mechanics, exhibiting mind-bending phenomena that challenge our understanding of the universe. One such phenomenon is quantum tunneling.

In quantum tunnels, particles appear to move faster than the speed of light, seemingly breaking the fundamental rules set by Einstein’s theory of relativity.

However, a group of physicists from TU Darmstadt has proposed a new method to measure the time it takes for particles to tunnel, suggesting that previous experiments may have been inaccurate.

This Interactive Museum Concept Lets You Experience Sound Paintings

In February, we covered a curious setup that allows you to control digital particles in real time by blowing air into a sensor, created by visual artist Steven Mark Kübler. But what if you had a whole museum of such unusual interactive artworks?

This is what Kübler has been wondering as well. He presented a concept of a room filled with sound paintings manipulated with viewers’ actions. You can see him blowing on the sensor to make particles in a tank-like container splash and part like water. The experience was created using Arduino’s controller and the TouchDesigner visual development platform.