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Category: quantum physics

Black holes may avoid singularities when charge and Hawking radiation combine, theoretical physicist argues

Black holes are regions in space where gravity is so strong that nothing, even light, can escape. Einstein’s theory of general relativity breaks down inside black holes, either by the presence of a so-called “curvature singularity” or “Cauchy horizon.”

A curvature singularity is a point where density and spacetime curvature become infinite, the laws of physics break down, and matter is crushed into an infinitely small space. A Cauchy horizon, on the other hand, is a boundary beyond which the future cannot be reliably predicted by known physics theories.

Francesco Di Filippo, a researcher at the Institute for Theoretical Physics in Frankfurt, recently carried out a theoretical study that challenges the assumption that black holes must inevitability possess either a singularity or a Cauchy horizon. His paper, published in Physical Review Letters, shows that the combination of electromagnetic repulsion from electric charge and quantum effects described by Stephen Hawking’s radiation theory could prevent the formation of singularities and Cauchy horizons in some black holes.

Quantum supremacy just ran into an unexpected rival: An ordinary laptop armed with new math

Using a conventional computer and cutting-edge mathematical tools and code, physicists at the Center for Computational Quantum Physics (CCQ) at the Simons Foundation’s Flatiron Institute and collaborators at Boston University have cracked a daunting quantum physics problem previously claimed to be solvable only by quantum computers.

The technique is so groundbreaking in its efficiency that the researchers were even able to use a personal laptop to solve the problem.

By enabling scientists to squeeze extra problem-solving power from classical computers, the breakthrough methodology is opening new avenues for research on quantum dynamics and may be useful as a protocol for solving problems about finding the optimal solution amid an abundance of feasible ones.

Molecule-in-a-crystal system could boost quantum computing via chemically engineered qubits

Within a crystal’s atomic structure, tiny atomic-scale flaws will naturally occur where electrons can become trapped. These defects have emerged as one of the leading platforms for quantum information processing. Through a new study, posted to the preprint server arXiv, Ilai Schwartz and colleagues at NVision Imaging Technologies in Germany have shown that a specialized molecule embedded inside a crystal could take this approach a step further, offering a more controllable and versatile route to building quantum systems.

Unlike the classical computers we use every day, quantum computers encode information in the quantum states of qubits, which can exist in combinations of 0 and 1 simultaneously. This quantum information can’t simply be copied or transmitted in the same way as classical bits: when a qubit is measured, its quantum state is disturbed, making it impossible to transmit its information directly.

To tackle this problem, qubits must be connected to photons, which can transmit their quantum information between distant parts of a network. This connection relies on what physicists call a “spin-photon interface”: a structure in which the quantum state of an electron or nucleus can be reliably written, read, and communicated via light.

Geordie Rose: Machine Learning is Progressing Faster Than You Think

“Machine learning is progressing faster than you think.”

Geordie Rose said that to me in 2013.

Back then, it sounded like the kind of thing a quantum computing CEO says to drum up attention. Today it reads like a weather report.

Thirteen years ago, the D-Wave founder and CTO sat down with me for over two hours and laid out a thesis most observers found extreme: machine learning would become broadly available far faster than anyone hoped, and quantum computers would help us build AI by 2029.

The 2029 date sounded like science fiction.

It does not sound like science fiction anymore.

Continue reading “Geordie Rose: Machine Learning is Progressing Faster Than You Think” | >

What if the direction of a magnet could shape the building blocks of life?

In a new discovery, researchers from the Hebrew University of Jerusalem and the Weizmann Institute of Science have found that something in the direction of a magnetic field can influence how molecules of life behave at the most fundamental level and how early chemical processes linked to life may have unfolded.

The study, published in Chem and led by Prof. Yossi Paltiel (Hebrew University) and Prof. Michal Sharon (Weizmann Institute), shows that tiny differences between atoms (different isotopes) can lead to measurable changes in molecular behavior when combined with an invisible quantum property known as electron spin. Separation of the different isotopes can be achieved by magnetic surfaces.

At the center of the story is L-methionine, an amino acid, a basic building block of life. Like other biological molecules, methionine has a specific “handedness,” meaning it exists in a form that is not identical to its mirror image. This property, called chirality, is a mystery: why did nature choose one “hand” over the other?

The complete evolution of spin glass from order to chaos

How come our universe is full of disorder, when all elementary particles appear to follow strictly ordered laws of physics? And are there organizing principles behind disorder and apparent chaos?

One avenue of studying these fundamental questions is through an assembly of spins: the quantum property that makes electrons behave like tiny bar magnets, with a preferred orientation of either up or down. Neighboring spins align either in parallel (up-up) or antiparallel (up-down-up-down), as in ferromagnets and antiferromagnets, respectively. This simple ruleset makes spin systems very attractive for studying the emergence of order.

However, while the theory of spin is well-established, creating the material conditions for observing spin disorder has proven notoriously elusive. While physicists have been able to create exotic materials that exhibit spin disorder, tracing the evolution from order to disorder within materials has been challenged by the lack of a clean starting point.

The quantum key to seeing through chaos

Researchers from the Institut des NanoSciences de Paris, the Kastler Brossel Laboratory and the University of Glasgow have developed an innovative method that renders a scattering medium transparent solely for information carried by entangled photon pairs, while the same medium remains completely opaque to classical light.

Their works are published in the journals Optica (optimization) and Nature Physics (selective image transmission).

Faithfully transmitting spatial information, such as the image of an object, is a major challenge in modern optics. However, this task becomes complex as soon as light travels through disordered media, such as biological tissues, atmospheric turbulence, or multimode optical fibers. In these environments, scattering scrambles the information, making the final image completely unreadable.

Quantum sensors use atoms, electrons and light as ultra‑steady rulers

Quantum computers get a lot of attention, even though they are not ready for prime time, but quantum sensors are already doing useful work. These sensors measure fields, forces and motion so small that ordinary background noise can drown them out. Some sensors are already in daily use, while others are moving from research labs into flight tests, hospitals and field instruments.

For example, a human brain produces magnetic signals in the femtotesla-to-picotesla range—billions of times weaker than a refrigerator magnet—far weaker than the magnetic noise in an ordinary room. That is why brain scanners that measure these signals need ultrasensitive detectors and strong magnetic shielding. In some hospitals, these detectors use quantum technology to help map brain activity before epilepsy surgery, without touching the brain.

Quantum sensors are showing up in other fields as well, including in navigation when GPS signals are jammed or spoofed, mapping gravity to reveal what’s underground, and boosting astronomers’ ability to measure gravitational waves. I am a photonics and quantum technologies researcher. My lab applies physics to develop a range of devices, including quantum sensors.

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