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Category: particle physics – Page 30

New method reveals quantum states using indirect measurements of particle flows

A team from UNIGE shows that it is possible to determine the state of a quantum system from indirect measurements when it is coupled to its environment.

What is the state of a quantum system? Answering this question is essential for exploiting quantum properties and developing new technologies. In practice, this characterization generally relies on direct measurements, which require extremely well-controlled systems, as their sensitivity to external disturbances can distort the results. This constraint limits their applicability to specific experimental contexts.

A team from the University of Geneva (UNIGE) presents an alternative approach, tailored to open quantum systems, in which the interaction with the environment is turned into an advantage rather than an obstacle. Published in Physical Review Letters —with the “Editor’s Suggestion” label—this work brings quantum technologies a step closer to real-world conditions.

An electrically powered source of entangled light on a chip

Quantum technologies are cutting-edge systems that can process, transfer, or store information leveraging quantum mechanical effects, particularly a phenomenon known as quantum entanglement. Entanglement entails a correlation between two or more distant particles, whereby measuring the state of one also defines the state of the others.

In recent years, quantum physicists and engineers have been trying to realize devices that operate leveraging the entanglement between individual particles of light (i.e., photons). The reliable operation of these devices relies on so-called entangled photon sources (EPSs), components that can generate entangled pairs of photons.

Researchers at University of Science and Technology of China, Jinan Institute of Quantum Technology, CAS Institute of Semiconductors and other institutes recently realized a new EPS integrated onto a single photonic chip, which can generate entangled photons via an electrically powered laser. Their study is published in Physical Review Letters.

New quantum boundary discovered: Spin size determines how the Kondo effect behaves

Collective behavior is an unusual phenomenon in condensed-matter physics. When quantum spins interact together as a system, they produce unique effects not seen in individual particles. Understanding how quantum spins interact to produce this behavior is central to modern condensed-matter physics.

Among these phenomena, the Kondo effect—the interaction between localized spins and conduction electrons—plays a central role in many quantum phenomena.

Yet in real materials, the presence of additional charges and orbital degrees of freedom make it difficult to isolate the essential quantum mechanism behind the Kondo effect. In these materials, electrons don’t just have spin, they also move around and can occupy different orbitals. When all these extra behaviors mix together, it becomes hard to focus only on the spin interactions responsible for the Kondo effect.

Ultrafast spectroscopy reveals step-by-step energy flow in germanium semiconductors

Whether in a smartphone or laptop, semiconductors form the basis of modern electronics and accompany us constantly in everyday life. The processes taking place inside these materials are the subject of ongoing research. When the electrons in a semiconductor material are activated using light or an electrical voltage, the excited electrons also set the atomic lattice in motion. This results in collective vibrations of the atoms, known as phonons or lattice vibrations, which interact with each other and with the electrons themselves.

These tiny lattice vibrations play a vital role in how energy flows and dissipates through the material—in other words, in how efficiently the energy is redistributed and how strongly the material heats up. Different approaches can be used to control and monitor the propagation of lattice vibrations—and therefore to make the semiconductor more effective and more efficient.

Detailed knowledge of the mechanisms of energy loss and potential overheating is essential in order to design new materials and devices that heat up less, recover faster or respond to external excitation more precisely. A team led by Professor Ilaria Zardo from the University of Basel reports on the unprecedented accuracy they achieved in measurements of energy flow processes within the semiconductor germanium, which is frequently used in computer technology. Their paper is published in Advanced Science.

First direct evidence of Migdal effect opens new path for dark matter search

In a landmark discovery that bridges nearly a century of theoretical physics, a Chinese research team has successfully captured the first direct evidence of the Migdal effect, a breakthrough with profound implications for probing dark matter—the invisible substance thought to make up roughly 85% of the universe.

The finding, published in the journal Nature, confirms a prediction made in 1939 by Soviet physicist Arkady Migdal: When an atomic nucleus suddenly gains energy—for instance, from a collision with a neutral particle (like a neutron or a dark matter candidate)—and recoils, the rapid shift in the atom’s internal electric field can eject one of its orbiting electrons.

For nearly nine decades, this “electron ejection” process remained purely theoretical. Direct evidence proved elusive because the effect occurs on an incredibly tiny scale and is easily masked by background noise from cosmic rays and natural radiation.

Observing the positronium beam as a quantum matter wave for the first time

One of the discoveries that fundamentally distinguished the emerging field of quantum physics from classical physics was the observation that matter behaves differently at the smallest scales. A key finding was wave-particle duality, the revelation that particles can exhibit wave-like properties.

This duality was famously demonstrated in the double-slit experiment. When electrons were fired through two slits, they created an interference pattern of light and dark fringes on a detector. This pattern showed that each electron behaved like a wave, with its quantum wave-function passing through both slits and interfering with itself. The same phenomenon was later confirmed for neutrons, helium atoms, and even large molecules, making matter-wave diffraction a cornerstone of quantum mechanics.

Copenhagen Researchers state the Universe responds to our Actions Even Retroactively

The copenhagen interpretation & retroactivity. quantum mechanics basics:

Particles exist in a superposition of states until observed.

Measurement “collapses” the wave function into a definite outcome.

Retrocausality Debate:

Some physicists have explored whether quantum events can appear to be influenced by future measurements.

This is sometimes described as the universe “responding retroactively,” but it’s a controversial interpretation, not mainstream science.

Continue reading “Copenhagen Researchers state the Universe responds to our Actions Even Retroactively” | >

Distorted honeycomb magnet edges closer to a quantum spin liquid

Neutron scattering and simulations reveal why a promising Kitaev candidate freezes into order instead of forming a quantum spin liquid.

Most magnets are predictable. Cool them down, and their tiny magnetic moments snap into place like disciplined soldiers. However, physicists have long suspected that, under the right conditions, magnetism might refuse to settle even in extreme cold.

This restless state, known as a quantum spin liquid, could unlock new kinds of particles and serve as a foundation for quantum technologies that are far more stable than today’s fragile systems.

At Oak Ridge National Laboratory (ORNL), researchers have now created and closely examined a new magnetic material that brings this strange possibility a little closer to reality, even if it doesn’t quite cross the finish line yet.

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