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Category: quantum physics – Page 22

3D atomic rearrangement creates 40,000 quantum defects in 40 minutes

It’s been 37 years since scientists first demonstrated the ability to move single atoms, suggesting the possibility of designing materials atom by atom to customize their properties. Today there are several techniques that allow researchers to move individual atoms in order to give materials exotic quantum properties and improve our understanding of quantum behavior.

But existing techniques can only move atoms across the surface of materials in two dimensions. Most also require painstakingly slow processes and high-vacuum, ultracold lab conditions.

Now a team of researchers at MIT, the Department of Energy’s Oak Ridge National Laboratory, and other institutions has created a way to precisely move tens of thousands of individual atoms within a material in minutes at room temperature. The approach uses a set of algorithms to carefully position an electron beam at specific locations of a material, then scan the beam to drive atomic motions.

Frank J. Tipler: The Laws of Physics Say The Singularity is Inevitable!

13 years ago, a Tulane physicist told me I didn’t understand the laws of physics.

That’s why, he said, I can’t see why the Singularity is inevitable. Or why it’s perfectly compatible with Christianity.

Fair enough.

Dr. Frank J. Tipler is the cosmologist behind the Omega Point. He is a professor of mathematical physics at Tulane University, and the author of The Anthropic Cosmological Principle, The Physics of Immortality, and The Physics of Christianity.

He didn’t come on Singularity FM to soften his views. He came to defend them.

In one hour we covered:

Continue reading “Frank J. Tipler: The Laws of Physics Say The Singularity is Inevitable!” | >

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.

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