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Category: quantum physics – Page 774

Powerful new magnet provides fresh insight into ‘frozen’ quantum materials

Researchers at the Department of Energy’s (DOE’s) Oak Ridge National Laboratory (ORNL) have finished the preliminary commissioning of a new 14-tesla magnet at the Spallation Neutron Source (SNS). This new sample environment allows researchers to explore the fundamental physics behind complex behavior of quantum matter.

The magnet, which also features an optional dilution refrigerator insert, is the latest low-temperature sample to be commissioned at SNS. Weighing 2,670 pounds and standing nearly 7 feet tall, this massive device is an excellent tool for researchers wanting to learn more about materials that exhibit quantum phenomena. Its powerful magnetic field forces quantum particles to behave in an orderly way, giving scientists the opportunity to locate patterns in otherwise disordered . And with its refrigerator—which can chill samples to −459.65° F—scientists can essentially “freeze” molecular vibrations in materials that might appear as background noise in neutron scattering studies. This allows for more accurate measurements of the excitations associated with quantum magnets.

“Quantum systems often lack discernible order. This makes it difficult to understand their fundamental characteristics. This new sample environment lets us bring order to these systems we’re interested in studying,” said Matt Stone, a lead instrument scientist at ORNL.

Intro to Quantum Computing

Quantum computing is seen by many as a technology of the future. In this article, we’re going to look at how to run some non-trivial programs on actual quantum computers. In particular, we’re going to discuss something called graph states. Graph states are used for quantum cryptography, quantum error correction, and measurement based quantum computing. If all of that sounds like a foreign language, that’s okay. We’re going to go through everything, from the ground up, and in detail…and don’t worry, we’ll keep it light and fun.

A Discovery That Long Eluded Physicists: Superconductivity to the Edge

Princeton researchers detect a supercurrent — a current flowing without energy loss — at the edge of a superconductor with a topological twist.

A discovery that long eluded physicists has been detected in a laboratory at Princeton. A team of physicists detected superconducting currents — the flow of electrons without wasting energy — along the exterior edge of a superconducting material. The finding was published May 1 in the journal Science.

The superconductor that the researchers studied is also a topological semi-metal, a material that comes with its own unusual electronic properties. The finding suggests ways to unlock a new era of “topological superconductivity” that could have value for quantum computing.

NASA tested an ‘impossible’ engine

Circa 2016

Researchers say the new ‘impossible’ drive could carry passengers and their equipment to the moon in as little as four hours.

A trip to Alpha Centauri, which would take tens of thousands of years now, could be reached in just 100 years.

The system is based on electromagnetic drive, or EMDrive, which converts electrical energy into thrust without the need for rocket fuel.

Scientists produce a magnetic nanocrystal with many potential applications

Spinels are oxides with chemical formulas of the type AB2O4, where A is a divalent metal cation (positive ion), B is a trivalent metal cation, and O is oxygen. Spinels are valued for their beauty, which derives from the molecules’ spatial configurations, but spinels in which the trivalent cation B consists of the element chrome (Cr) are interesting for a reason that has nothing to do with aesthetics: They have magnetic properties with an abundance of potential technological applications, including gas sensors, drug carriers, data storage media, and components of telecommunications systems.

A study by Brazilian and Indian researchers investigated a peculiar kind of spinel: zinc-doped manganese chromite. Nanoparticles of this material, described by the formula Mn0.5 Zn0.5 Cr2O4 [where manganese (Mn) and zinc (Zn) compose the A-site divalent cation], were synthesized in the laboratory and characterized by calculations based on density functional theory (DFT), a method derived from that is used in solid-state physics and chemistry to resolve complex crystal structures.

The material’s structural, electronic, vibrational and were determined by X-ray diffraction, neutron diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. A report of the study has been published in the Journal of Magnetism and Magnetic Materials with the title “Structural, electronic, vibrational and magnetic properties of Zn2+ substituted MnCr2O4 nanoparticles.”

To make an atom-sized machine, you need a quantum mechanic

Here’s a new chapter in the story of the miniaturisation of machines: researchers in a laboratory in Singapore have shown that a single atom can function as either an engine or a fridge. Such a device could be engineered into future computers and fuel cells to control energy flows.

“Think about how your computer or laptop has a lot of things inside it that heat up. Today you cool that with a fan that blows air. In nanomachines or quantum computers, small devices that do cooling could be something useful,” says Dario Poletti from the Singapore University of Technology and Design (SUTD).

This work gives new insight into the mechanics of such devices. The work is a collaboration involving researchers at the Centre for Quantum Technologies (CQT) and Department of Physics at the National University of Singapore (NUS), SUTD and at the University of Augsburg in Germany. The results were published in the peer-reviewed journal npj Quantum Information on 1 May.

Does Consciousness Influence Quantum Mechanics?

Education Saturday with Space Time.

It’s not surprising that the profound weirdness of the quantum world has inspired some outlandish explanations – nor that these have strayed into the realm of what we might call mysticism. One particularly pervasive notion is the idea that consciousness can directly influence quantum systems – and so influence reality. Today we’re going to see where this idea comes from, and whether quantum theory really supports it.

The behavior of the quantum world is beyond weird. Objects being in multiple places at once, communicating faster than light, or simultaneously experiencing multiple entire timelines … that then talk to each other. The rules governing the tiny quantum world of atoms and photons seem alien. And yet we have a set of rules that give us incredible power in predicting the behavior of a quantum system – rules encapsulated in the mathematics of quantum mechanics. Despite its stunning success, we’re now nearly a century past the foundation of quantum mechanics and physicists are still debating how to interpret its equations and the weirdness they represent.

Could Photonic Chips Outpace the Fastest Supercomputers?

There’s been a lot of talk about quantum computers being able to solve far more complex problems than conventional supercomputers. The authors of a new paper say they’re on the pat h to showing an optical computer c an do so, too.

The idea of using light to carry out computing has a long pedigree, and it has gained traction in recent years with the advent of silicon photonics, which makes it possible to build optical circuits using the same underlying technology used for electronics. The technology s hows particular promise for accelerating deep learning, and is being actively pursued by Intel and a number of startups.

Now Chinese researchers have put a photonic chip t o work tackling a fiendishly complex computer science challenge called the s ubset sum problem in a paper in Science Advances. It ha s some potential applications in cryptography and resource allocation, but primarily it’s used as a benchmark to test the limits of computing.

Researchers see path to quantum computing at room temperature

Army researchers predict quantum computer circuits that will no longer need extremely cold temperatures to function could become a reality after about a decade.

For years, solid-state quantum technology that operates at room temperature seemed remote. While the application of transparent crystals with had emerged as the most likely route to this milestone, the plausibility of such a system always remained in question.

Now, Army scientists have officially confirmed the validity of this approach. Dr. Kurt Jacobs, of the U.S. Army Combat Capabilities Development Command’s Army Research Laboratory, working alongside Dr. Mikkel Heuck and Prof. Dirk Englund, of the Massachusetts Institute of Technology, became the first to demonstrate the feasibility of a quantum logic gate comprised of and optical crystals.

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