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Category: quantum physics – Page 342

Structured light waves with spiral phase fronts carry orbital angular momentum (OAM), attributed to the rotational motion of photons. Recently, scientists have been using light waves with OAM, and these special “helical” light beams have become very important in various advanced technologies like communication, imaging, and quantum information processing. In these technologies, it’s crucial to know the exact structure of these special light beams. However, this has proven to be quite tricky.

Interferometry—superimposing a with a known reference field to extract information from the interference—can retrieve OAM spectrum information using a camera. As the camera only records the intensity of the interference, the measurement technique encounters additional crosstalk known as “signal-signal beat interference” (SSBI), which complicates the retrieval process. It’s like hearing multiple overlapping sounds, making it difficult to distinguish the original notes.

In a recent breakthrough reported in Advanced Photonics, researchers from Sun Yat-sen University and École Polytechnique Fédérale de Lausanne (EPFL) used a powerful mathematical tool called the Kramers-Kronig (KK) relation, which helps with understanding and solving the problem. This tool enabled them to untangle the complex helical pattern from the camera’s intensity-only measurements for single-shot retrieval in simple on-axis interferometry. Exploring the duality between the time-frequency and azimuth-OAM domains, they apply the KK approach to investigate various OAM fields, including Talbot self-imaged petals and fractional OAM modes.

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Quantum emission is pivotal to realizing photonic quantum technologies. Solid-state single photon emitters (SPEs), such as hexagonal boron nitride (hBN) defects, operate at room temperature. They are highly desirable due to their robustness and brightness.

The conventional way to collect photons from SPEs relies on a high numerical aperture (NA) objective lens or micro-structured antennas. While photon collection efficiency can be high, these tools cannot manipulate quantum emissions. Multiple bulky optical elements, such as polarizers and phase plates, are required to achieve any desired structuring of the emitted quantum light source.

In a new paper published in eLight, an international team of scientists led by Drs Chi Li and Haoran Ren from Monash University have developed a new multifunctional metalens for structuring quantum emissions from SPEs.

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Weird things happen on the quantum level. Whole clouds of particles can become entangled, their individuality lost as they act as one.

Now scientists have observed, for the first time, ultracold atoms cooled to a quantum state chemically reacting as a collective, rather than haphazardly forming new molecules after bumping into each other by chance.

“What we saw lined up with the theoretical predictions,” says Cheng Chin, a physicist at the University of Chicago and senior author of the study. “This has been a scientific goal for 20 years, so it’s a very exciting era.”

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DNA sequencing technology, i.e., determining the order of nucleotide bases in a DNA molecule, is central to personalized medicine and disease diagnostics, yet even the fastest technologies require hours, or days, to read a complete sequence. Now, a multi-institutional research team led by The Institute of Scientific and Industrial Research (SANKEN) at Osaka University, has developed a technique that could lead to a new paradigm for genomic analysis.

DNA sequences are sequential arrangements of the nucleotide bases, i.e., the four letters that encode information invaluable to the proper functioning of an organism. For example, changing the identity of just one nucleotide out of the several billion nucleotide pairs in the can lead to a serious medical condition. The ability to read DNA sequences quickly and reliably is thus essential to some urgent point-of-care decisions, such as how to proceed with a particular chemotherapy treatment.

Unfortunately, genome analysis remains challenging for , and it’s in this context that quantum computers show promise. Quantum computers use quantum bits instead of the zeroes and ones of classical computers, facilitating an exponential increase in computational speed.

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For the first time ever, research scientists at the Massachusetts Institute of Technology (MIT) with the Institute for Soldier Technologies have demonstrated a level of control over the phenomenon known as quantum randomness.

If perfected, controlling quantum randomness could lead to a number of scientific breakthroughs, including the ability to perform previously impossible probabilistic quantum computing and advanced field sensing technologies.

Are Vacuum Fluctuations in the Quantum World Uncontrollable?

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“This has been a scientific goal for 20 years, so it’s a very exciting era.”

In a significant advance, scientists have obtained the first proof of a phenomenon known as “quantum superchemistry.” This effect was previously predicted but never actually observed in the laboratory.

The University of Chicago researchers that led this experiment characterize quantum superchemistry as a “phenomenon where particles in the same quantum state undergo collectively accelerated reactions.”

John Zich.

This effect was previously predicted but never actually observed in the laboratory.

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Are quantum events required for consciousness in a very special sense, far beyond the general sense that quantum events are part of all physical systems? What would it take for quantum events, on such a micro-scale, to be relevant for brain function, which operates at the much higher level of neurons and brain circuits? What would it mean?

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Donald D. Hoffman is Professor of Cognitive Science, University of California, Irvine and author of Visual Intelligence: How We Create What We See and coauthor of Observer Mechanics: A Formal Theory Of Perception.

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Just as carbon makes up both the brittle core of a No. 2 pencil and the harder-than-steel diamond in a cutting tool, boron nitride gives rise to compounds that can be soft or hard. Yet, unlike carbon, far less is known about boron nitride’s forms and their responses to changing temperatures and pressures.

Rice University scientists mixed —a soft variety also known as “white graphite”—with cubic boron nitride—a material second to diamond in hardness—and found that the resulting nanocomposite interacted with light and heat in unexpected ways that could be useful in next-generation microchips, quantum devices and other advanced technology applications.

“Hexagonal boron nitride is widely used in a variety of products, such as coatings, lubricants and cosmetics,” said Abhijit Biswas, a research scientist who is the lead author of a study about the research published in Nano Letters. “It’s quite soft and it is a great lubricant, and very lightweight. It’s also cheap and very stable at room temperature and under atmospheric pressure.

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