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Category: quantum physics – Page 590

Sophomore math major Xzavier Herbert was never much into science fiction or the space program, but his skills in pure mathematics seem to keep drawing him into NASA’s orbit.

With an interest in representation theory, Herbert spent the summer virtually at NASA, studying connections between classical information theory and quantum information theory, each of which corresponds to a different set of laws: classical physics and quantum mechanics.

“What I’m doing involves how representation theory allows us to draw a direct analog from classical information theory to quantum information theory,” Herbert says. “It turns out that there is a mathematical way of justifying how these are related.”

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While researchers have conducted countless studies exploring the interaction between light waves and bound electron systems, the quantum interactions between free electrons and light have only recently become a topic of interest within the physics community. The observation of free electron-light interactions was facilitated by the discovery of a technique known as photon-induced near-field electron microscopy (PINEM).

Although some experiments using PINEM methods have yielded interesting results, the free-electron interactions observed so far are fairly weak. This is mainly because PINEM methods gather localized and near-field measurements without addressing the velocity mismatch between free electrons and light, which is known to limit the strength of their interaction.

Researchers at Technion–Israel Institute of Technology have recently observed a between free electron waves and , using a hybrid electron microscope they developed. Their observation of coherent electron phase matching, which is also a type of inverse-Cherenkov interaction, demonstrates how the nature of electron wavefunctions can alter electron-light interactions.

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Most materials used for optical lighting applications need to produce a uniform illumination and require high mechanical and hydrophobic properties. However, they are rarely eco-friendly. Herein, a bio-based, polymer matrix-free, luminescent, and hydrophobic film with excellent mechanical properties for optical lighting purposes is demonstrated. A template is prepared by turning a wood veneer into porous scaffold from which most of the lignin and half of the hemicelluloses are removed. The infiltration of quantum dots (CdSe/ZnS) into the porous template prior to densification resulted in almost uniform luminescence (isotropic light scattering) and could be extended to various quantum dot particles, generating different light colors. In a subsequent step, the luminescent wood film is coated with hexadecyltrimethoxysilane (HDTMS) via chemical vapor deposition. The presence of the quantum dots coupled with the HDTMS coating renders the film hydrophobic (water contact angle ≈ 140°). This top-down process strongly eliminates lumen cavities and preserves the orientation of the original cellulose fibrils to create luminescent and polymer matrix-free films with high modulus and strength in the direction of fibers. The proposed optical lighting material could be attractive for interior designs (e.g., lamps and laminated cover panels), photonics, and laser devices.

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Three-dimensional (3D) nanostructured materials—those with complex shapes at a size scale of billionths of a meter—that can conduct electricity without resistance could be used in a range of quantum devices. For example, such 3D superconducting nanostructures could find application in signal amplifiers to enhance the speed and accuracy of quantum computers and ultrasensitive magnetic field sensors for medical imaging and subsurface geology mapping. However, traditional fabrication tools such as lithography have been limited to 1-D and 2-D nanostructures like superconducting wires and thin films.

Now, scientists from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, Columbia University, and Bar-Ilan University in Israel have developed a platform for making 3D superconducting nano-architectures with a prescribed organization. As reported in the Nov. 10 issue of Nature Communications, this platform is based on the self-assembly of DNA into desired 3D shapes at the nanoscale. In DNA self-assembly, a single long strand of DNA is folded by shorter complementary “staple” strands at specific locations—similar to origami, the Japanese art of paper folding.

“Because of its structural programmability, DNA can provide an assembly platform for building designed nanostructures,” said co-corresponding author Oleg Gang, leader of the Soft and Bio Nanomaterials Group at Brookhaven Lab’s Center for Functional Nanomaterials (CFN) and a professor of chemical engineering and of applied physics and at Columbia Engineering. “However, the fragility of DNA makes it seem unsuitable for functional device fabrication and nanomanufacturing that requires inorganic materials. In this study, we showed how DNA can serve as a scaffold for building 3D nanoscale architectures that can be fully “converted” into inorganic materials like superconductors.”

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Bristol researchers have developed a tiny device that paves the way for higher performance quantum computers and quantum communications, making them significantly faster than the current state-of-the-art.

Researchers from the University of Bristol’s Quantum Engineering Technology Labs (QET Labs) and Université Côte d’Azur have made a new miniaturized detector to measure quantum features of light in more detail than ever before. The device, made from two working together, was used to measure the of “squeezed” quantum light at record high speeds.

Harnessing unique properties of quantum physics promises novel routes to outperform the current state-of-the-art in computing, communication and measurement. Silicon photonics—where light is used as the carrier of information in silicon micro-chips—is an exciting avenue towards these next-generation technologies.

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Superconductors – materials in which electricity flows without any resistance whatsoever – could be extremely useful for future electronics. Now, engineers at the University of Tokyo have managed to create a superconductor out of a state of matter called a Bose-Einstein condensate (BEC) for the first time ever.

Sometimes called the fifth state of matter, behind the more commonly known solids, liquids, gases and plasmas, Bose-Einstein condensates are what happens when you cool a gas of bosons right down to almost the coldest temperature possible. Experiments have shown that at this point, quantum phenomena can be observed at the macro scale. Scientists have used BECs as a starting point to create exotic states of matter like supersolids, excitonium, quantum ball lightning, and fluids exhibiting negative mass.

“A BEC is a unique state of matter as it is not made from particles, but rather waves,” says Kozo Okazaki, lead author of the study. “As they cool down to near absolute zero, the atoms of certain materials become smeared out over space. This smearing increases until the atoms – now more like waves than particles – overlap, becoming indistinguishable from one another. The resulting matter behaves like it’s one single entity with new properties the preceding solid, liquid or gas states lacked.”

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Circa 2006

Quantum cryptography (QC) is still in a very early stage and there are very few commercial products available. But this doesn’t prevent researchers to look at new solutions. For example, physicists from the University of Wien, Austria, are testing qutrits instead of the more common qubits. These qutrits can simultaneously exist in three basic states — instead of two for the qubits. This means that QC systems based on qutrits will inherently be more secure. But if QC using qubits has been demonstrated over distances exceeding 100 kilometers, the experiments with qutrits are today confined within labs. For more information, read this abstract of a highly technical paper or continue below.

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Scientists have successfully teleported a three-dimensional quantum state. The international effort between Chinese and Austrian scientists could be crucial for the future of quantum computers.

The researchers, from Austrian Academy of Sciences, the University of Vienna, and University of Science and Technology of China, were able to teleport the quantum state of one photon to another distant state. The three-dimensional transportation is a huge leap forward. Previously, only two-dimensional quantum teleportation of qubits has been possible. By entering a third dimension, the scientists were able to transport a more advanced unit of quantum information known as a “qutrit.”

Quantum computing is different than what’s known as classical computing, which is what powers phones and laptops. These traditional devices store information in bits, which are represented with a binary 0 or 1. A good metaphor is to imagine a circle, where each 0 and 1 are on opposite points. In Quantum computing, which deals with atomic and subatomic particles, qubits can exist at both of those points as well as anywhere else in the circle.

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We probably think we know gravity pretty well. After all, we have more conscious experience with this fundamental force than with any of the others (electromagnetism and the weak and strong nuclear forces). But even though physicists have been studying gravity for hundreds of years, it remains a source of mystery.

In our video Why Is Gravity Different? We explore why this force is so perplexing and why it remains difficult to understand how Einstein’s general theory of relativity (which covers gravity) fits together with quantum mechanics.

Gravity is extraordinarily weak and nearly impossible to study directly at the quantum level. We cannot scrutinize it using particle accelerators like we can with the other forces, so we need other ways to get at quantum gravity.

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