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Category: quantum physics

Largest-ever survey of physicists puts Standard Model of cosmology under scrutiny

The largest-ever survey of physicists from around the world—released today—shows a distinct lack of consensus across many of physics’s most important questions, from the nature of black holes and dark matter, to the still-incomplete unification of Einstein’s theory of gravity with quantum mechanics.

Even the best theory of the universe’s expansion, known as the standard model of cosmology or ΛCDM (Lambda Cold Dark Matter), did not attain majority support. This surprising outcome is perhaps due to results from the Dark Energy Spectroscopic Instrument (DESI) last year, which hinted that dark energy may change over time, in opposition to the standard model’s conviction that dark energy remains constant.

But that wasn’t the only surprising outcome. The survey doesn’t seem to find much agreement anywhere.

Atoms vibrate on circular paths—with an unexpected twist

An international team of researchers, including scientists from HZDR and Fritz Haber Institute of the Max Planck Society, for the first time directly observed how angular momentum is transferred and conserved within a crystal lattice. Using intense terahertz laser pulses, the researchers were able to selectively control these processes, which unveiled a surprising effect: During the angular momentum transfer, the direction of rotation reverses—caused by the rotational symmetry of the material.

The results, published in Nature Physics, provide new insights into the foundation of magnetism and open up possibilities for tailored control of quantum materials.

Conserved quantities such as energy, momentum, and angular momentum determine the fundamental laws of nature. In a closed system, these quantities are always conserved: they cannot be created or destroyed, only transformed or transferred. While angular momentum is familiar in everyday life through rotating carousels or riding a bicycle, it plays a central role at the quantum level—for example, as the fundamental origin of magnetism.

How temperature changes light: New model could guide smarter LEDs, sensors and photonic devices

Technion researchers have developed, for the first time, a comprehensive physical model explaining how the properties of a radiating material, including absorption, emission, and quantum efficiency, affect the fundamental characteristics of the light it emits as a function of temperature. In essence, the emitted light changes its color, intensity, and randomness according to the material’s properties and its temperature. The discovery was published in Optica and opens new possibilities for designing advanced light sources, optical sensors, and thermally based photonic systems.

The research was led by M.Sc. student Tomer Bar-Lev and Prof. Carmel Rotschild from the Faculty of Mechanical Engineering and the Russell Berrie Nanotechnology Institute at the Technion. According to the researchers, the central phenomenon examined in this work is photoluminescence, a process in which a material emits light in response to incident illumination. In this phenomenon, light particles (photons) are absorbed by the material and re-emitted, forming the basis of many technologies, including LED lighting and optical sensors.

The Technion researchers demonstrated that the influence of fundamental physical laws formulated more than a century ago is far broader than previously thought.

New quantum protocol breaks distance and speed barriers in fiber networks

Scientists at the University of Science and Technology of China have successfully deployed a multi-mode quantum relay network, achieving matter–matter entanglement over 14.5 kilometers, according to media reports.

The system, known as Xinghan-2, was detailed in the journal Nature Photonics on May 7. It addresses a key bottleneck in quantum communication by achieving both high transmission rates and high fidelity at the same time.

Quantum relays are seen as essential for the future quantum internet, as they help prevent signal loss over long distances by dividing communication channels into shorter segments. Previous approaches often involved a trade-off between the high speeds of single-photon interference and the high precision of two-photon interference.

This Magnetic Field Trick Creates Entirely New Forms of Matter

Scientists have shown that changing magnetic fields in precise ways can create exotic quantum matter that does not normally exist. The discovery could eventually lead to more reliable quantum technologies and powerful new computing systems.

Quantum technology is widely seen as one of the most promising future tools for processing massive and complicated amounts of information. Although most quantum systems are still confined to laboratories and research facilities, scientists are steadily working toward applications that could eventually impact industries across the economy.

Magnetic fields and exotic quantum states.

In Quantum Gravity, the Cosmological Constant May Behave Similar To The Quantum Hall Effect

So why not do the same thing for a gravitational field? Well, it turns out that quantum renormalization only works for Euclidean space. In general relativity, the mass-energy of a system warps space and time. So all those quantum fluctuations curve spacetime, and curved spacetime induces even more virtual particles, which warp space even more… oh no! It all breaks down, and we can’t quantize gravitational fields the way we quantize the other fundamental forces.

Problems like these have led some researchers to develop a model known as loop quantum gravity. Rather than trying to calculate the behavior of quantum particles in a timey-wimey background, why not treat the entire mass-energy-spacetime structure as a single quantum system? It’s like imagining the Universe within an unseen background that is Euclidean. This way the problem of renormalization can be overcome in many cases. One case where it doesn’t work well is the cosmological constant. In most cosmological models, the cosmological constant is what drives cosmic expansion. Since it is a universal dark energy field, it amplifies the loop quantum gravity sums, and once again the whole thing diverges. You can handle this by fixing the cosmological constant to a specific value, but that isn’t really a solution to the problem. It’s the cosmology equivalent of ignoring the engine light in your car…

A new study finds this might not be too bad after all. In it, the authors demonstrate an interesting similarity between the cosmological constant in loop quantum gravity and the quantum Hall effect in standard quantum theory.

Quantum circuit test finally exposes what has been warping performance

Quantum computers could someday solve pressing problems that are too convoluted for classical computers, such as modeling complex molecular interactions to streamline drug discovery and materials development.

But to build a superconducting quantum computer that is large and resilient enough for real-world applications, scientists must precisely engineer thousands of quantum circuits so they perform operations with the lowest possible error rate.

To help scientists design more predictable circuits, researchers from MIT and Lincoln Laboratory developed a technique to measure a property that can unexpectedly cause a superconducting quantum circuit to deviate from its expected behavior. Their analysis revealed the source of these distortions, known as second-order harmonic corrections, leading to underperforming circuit architectures.

Method for measuring energy amounts less than a trillionth of a billionth of a joule could boost quantum computing

The fundamentals of quantum mechanics are minuscule. Scientists constantly home in on finer resolutions to measure, quantify, and control these fundamentals, like photons that carry light and have no mass unless they are moving. The more precise the measurement, the more possibilities for better quantum technology or the ability to detect elusive dark-matter axions in deep space.

Now, researchers in Finland have successfully used a calorimeter, a type of ultra-sensitive heat-based energy sensor, to detect energy levels below one zeptojoule, or a trillionth of a billionth of a joule. For context, a zeptojoule is approximately the amount of work it takes for a red blood cell to move a nanometer, or a billionth of a meter, upwards in Earth’s gravity.

The team, led by Academy Professor Mikko Möttönen at Aalto University, together with industry collaborator IQM and the Technical Research Centre of Finland (VTT), used a novel technique to achieve the milestone measurement. The study is published in the journal Nature Electronics.

Resilient quantum sensor monitors Earth’s magnetic field from space for 10 months

From navigation to solar weather forecasting, many different areas of research require space-based sensors to measure Earth’s magnetic field as accurately as possible at any given moment. So far, however, existing sensors have consistently struggled with effects including drift, interference from the spacecraft itself, and the harsh conditions of orbit.

Through new research published in Physical Review Applied, Yarne Beerden and colleagues at Hasselt University in Belgium have developed a diamond-based quantum sensor which could offer a promising solution to these problems.

Quantum dot emitter delivers near-identical telecom photons at 40 million per second

Quantum technologies, devices that perform specific functions leveraging quantum mechanical effects, could soon outperform their classical counterparts on some tasks. Quantum emitters, devices that release individual particles of light (i.e., photons), are central components of many of these technologies, including quantum communication systems and quantum computers.

To enable the reliable operation of quantum technologies, emitters should emit photons with high consistency and coherence. In other words, they should ensure that the quantum properties of emitted photons remain stable and predictable.

Researchers at University of Copenhagen’s Niels Bohr Institute, Ruhr-University Bochum, University of Basel and Sparrow Quantum ApS recently developed a new photon emitter based on quantum dots, tiny structures that can trap electrons in confined regions and enable the controlled emission of individual photons.

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