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Category: quantum physics

New Approach to Controlling Light Signals

A concept based on an exotic effect in periodic structures may be useful for developing future photonic devices.

A new way to marshal light within optical devices has been demonstrated experimentally by researchers in China. They have been able to induce light to organize itself into specific patterns of pulses as it circulates within a pair of optical fiber loops using a version of a phenomenon—called the non-Hermitian skin effect (NHSE)—that has been predicted but not observed previously [1]. The effect could be used to control light signals in photonic devices such as switches and routers.

In the standard theory for electron behavior in a metallic crystal, the periodic atomic structure leads to so-called Bloch waves—electron quantum states that spread across the entire crystal. But in recent years, theorists have found surprising results for a scenario in which one assumes that a particle such as an electron hops between neighboring sites in a periodic lattice asymmetrically—say, rightward hopping is more probable than leftward hopping. The particle’s quantum states become localized at the edge or surface of the lattice rather than spreading across it. This localization is the NHSE.

Quantum spin currents in graphene without external magnetic fields pave way for ultra-thin spintronics

Scientists from TU Delft (The Netherlands) have observed quantum spin currents in graphene for the first time without using magnetic fields. These currents are vital for spintronics, a faster and more energy-efficient alternative to electronics. This breakthrough, published in Nature Communications, marks an important step towards technologies like quantum computing and advanced memory devices.

Quantum physicist Talieh Ghiasi has demonstrated the quantum Hall (QSH) effect in graphene for the first time without any external magnetic fields. The QSH effect causes electrons to move along the edges of the graphene without any disruption, with all their spins pointing in the same direction.

“Spin is a quantum mechanical property of electrons, which is like a tiny magnet carried by the electrons, pointing up or down,” Ghiasi explains. “We can leverage the spin of electrons to transfer and process information in so-called spintronics devices. Such circuits hold promise for next-generation technologies, including faster and more energy-efficient electronics, quantum computing, and advanced memory devices.”

Metal-organic frameworks with metallic conductivity pave new paths for electronics and energy storage

Metal-organic frameworks (MOFs) are characterized by high porosity and structural versatility. They have enormous potential, for example, for applications in electronics. However, their low electrical conductivity has so far greatly restricted their adoption.

Using AI and robot-assisted synthesis in a self-driving laboratory, researchers from Karlsruhe Institute of Technology (KIT), together with colleagues in Germany and Brazil, have now succeeded in producing an MOF thin film that conducts electricity like metals. This opens up new possibilities in electronics and —from sensors and quantum materials to functional materials.

The team reports on this work in the Materials Horizons journal.

Researchers confirm fundamental conservation laws at the quantum level

Researchers at Tampere University and their collaborators from Germany and India have experimentally confirmed that angular momentum is conserved when a single photon is converted into a pair – validating a key principle of physics at the quantum level for the first time. This breakthrough opens new possibilities for creating complex quantum states useful in computing, communication, and sensing.

Conservation laws are the heart of our natural scientific understanding as they govern which processes are allowed or forbidden. A simple example is that of colliding billiard balls, where the motion – and with it, their linear momentum – is transferred from one ball to another. A similar conservation rule also exists for rotating objects, which have angular momentum. Interestingly, light can also have an angular momentum, e.g., orbital angular momentum (OAM), which is connected to the light’s spatial structure.

In the quantum realm, this implies that single particles of light, so-called photons, have well-defined quanta of OAM, which need to be conserved in light-matter interactions. In a recent study in Physical Review Letters, researchers from Tampere University and their collaborators, have now pushed the test of these conservation laws to absolute quantum limit. They explore if the conservation of OAM quanta holds when a single photon is split into a photon pair.

Quantum breakthrough: ‘Magic states’ now easier, faster, and way less noisy

Quantum computing just got a significant boost thanks to researchers at the University of Osaka, who developed a much more efficient way to create “magic states”—a key component for fault-tolerant quantum computers. By pioneering a low-level, or “level-zero,” distillation method, they dramatically reduced the number of qubits and computational resources needed, overcoming one of the biggest obstacles: quantum noise. This innovation could accelerate the arrival of powerful quantum machines capable of revolutionizing industries from finance to biotech.

Physicists confirm elusive quantum spin liquid in new study

An international team of scientists led by Rice University’s Pengcheng Dai has confirmed the existence of emergent photons and fractionalized spin excitations in a rare quantum spin liquid. Published in Nature Physics on June 19, their findings identify the crystalline compound cerium zirconium oxide (Ce₂Zr₂O₇) as a clear 3D realization of this exotic state of matter.

Long a subject of theoretical intrigue, quantum spin liquids offer promise for revolutionary technologies, including and dissipationless energy transmission. By refusing to conform to traditional magnetic behavior, these materials realize emergent quantum electrodynamics via highly quantum-entangled motions of magnetic moments at temperatures near absolute zero.

“We’ve answered a major open question by directly detecting these excitations,” said Dai, the Sam and Helen Worden Professor of Physics and Astronomy. “This confirms that Ce₂Zr₂O₇ behaves as a true quantum spin ice, a special class of quantum spin liquids in three dimensions.”

Near-perfect defects in 2D material could serve as quantum bits

Scientists across the world are working to make quantum technologies viable at scale—an achievement that requires a reliable way to generate qubits, or quantum bits, which are the fundamental units of information in quantum computing.

The task has so far remained elusive, but one of the materials that has garnered a lot of attention as a possible qubit platform is (h-BN), a 2D material that can host solid-state single-photon emitters (SPEs). Like the name indicates, SPEs are atomic structures in solid materials that can produce individual photons.

In a new study published in Science Advances, researchers at Rice University and collaborators at Oak Ridge National Laboratory and the University of Technology, Sydney report the first demonstration of low noise, room-temperature quantum emitters in h-BN made through a scalable growth technique.