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Category: quantum physics – Page 39

Nanoparticle Motion Measured Beyond Quantum Limit

Researchers boosted the sensitivity for measurements of the motion of a levitated nanoparticle, with potential uses in dark matter searches.

Researchers have a bold plan to detect unknown fundamental particles: Levitate a nanoscale object in a vacuum and watch for a microscopic recoil caused by a collision with an exotic particle. Precision measurements of macroscopic objects have been a challenge, but now a research team has demonstrated a significant sensitivity improvement with a levitated object some 6 orders of magnitude larger than in previous experiments [1]. The team hopes the method will find use in experimental searches in the next few years.

Searching for particles not accounted for by the standard model of particle physics requires experiments with unprecedented sensitivity. One method is to use laser light to levitate a small object in a vacuum, isolating it from surrounding noise. Researchers can monitor its motion and potentially detect minuscule recoils caused by rare collisions with exotic particles, such as those of dark matter.

Scientist creates ‘mini‑universe’ to measure time without a clock

A University of Birmingham scientist has built a “mini-universe” that takes a step toward answering one of science’s biggest questions: “What is time?” Publishing his findings in Physical Review Research, Professor Giovanni Barontini shows how it is possible to measure the flow of time without using a clock at all. The new findings provide a scientific model in which a version of time emerges from the experiment itself.

Some theories of physics, such as the Wheeler–DeWitt equation, suggest that, at its deepest level, the universe has no built-in time but exists as a single, unchanging quantum state in which particles exhibit both wave-like and particle-like properties. It treats the universe as a whole with no external clock, and any sense of time must emerge from internal relationships between parts.

Nuclear clocks tick for the first time

Two independent research teams have achieved a longstanding goal in physics: building a working nuclear clock. The devices, developed by Beichen Huang and colleagues at Tsinghua University and by Luca Toscani De Col and colleagues at the Vienna Center for Quantum Science and Technology in Austria, exploit the nucleus of a thorium-229 atom to keep time with extraordinary precision—possibly surpassing even the best atomic clocks available today.

The Chinese and European studies have both been published in preprint on arXiv.

Engineering quantum Hall stripes in 2D materials inside electromagnetic cavities

Quantum materials, materials with properties that are governed by the laws of quantum mechanics, have proved to be highly promising for the development of ultra-efficient electronic devices, quantum processors, highly precise sensors and various other technologies. Reliably controlling these materials’ quantum phases would be highly advantageous, as it would enable engineers to tailor and optimize their properties for specific applications.

Researchers at ETH Zurich, in the Quantum Optoelectronics Group led by Prof. Dr. Jérôme Faist and Prof. Dr. Giacomo Scalari, have uncovered a new strategy to stabilize self-organized electronic patterns known as quantum Hall stripes in two-dimensional (2D) electron systems.

Their approach, outlined in a paper published in Nature Physics, entails creating high-quality 2D electron systems, embedding them into carefully designed cavities (i.e., structures that confine electromagnetic fields) and cooling them to ultralow temperatures.

Quantum friction causes light to slow down nanoworld movements

A research team in Bochum, Germany has unexpectedly found that light can slow down movements in the nanoworld. This is due to quantum friction, a phenomenon that has been poorly understood until now. The findings are published in the journal Nature.

Light is expected to heat particles up or set them in motion. However, the interdisciplinary team at Ruhr University Bochum, Germany, has now proven the opposite. In aqueous solution, fluorescent carbon nanotubes move much slower once they are irradiated with light. During this process, the diffusion constant decreases with light intensity, an effect linked to direct coupling between electrons in the solid and the molecules of the liquid.

“This discovery of light-induced quantum friction fundamentally changes our understanding of interfacial processes,” says researcher Sebastian Kruss, who led the work with Marialore Sulpizi and Martina Havenith.

One-way quantum synchronization could make quantum computers more reliable

Scientists at RIKEN have proposed a new way to make quantum systems synchronize in only one direction—like a one-way street for sound particles known as phonons. The breakthrough combines two quantum effects to create a form of one-way quantum synchronization that remains surprisingly stable even when exposed to manufacturing flaws and environmental noise, two major obstacles that have long hindered real-world quantum technologies.

Electron matter waves gain ultrafast torque that flips handedness in femtoseconds

Many natural processes, ranging from magnetism to chemical reactions, entail the movement and rotation of particles at very small scales. In quantum mechanics, particles exhibit both particle-like and wave-like behaviors, and their states can be described mathematically using representations known as wavefunctions.

The reliable manipulation of wave-like properties of particles as small as atoms or single electrons could open new possibilities both for studying matter and for engineering materials with desirable characteristics. Notably, controlling the angular momentum, which is the quantum property related to rotational motion, of ultrasmall particles at ultrafast timescales has so far proved very challenging when only using conventional, laser-based approaches.

Researchers at Universität Konstanz recently devised a new approach to create electron beams with an ultrafast internal torque (i.e., twisting motion). Their proposed strategy, outlined in a paper published in Nature Physics, could be a promising tool for exploring material dynamics and quantum phenomena at atomic and subatomic scales.

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