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Category: quantum physics – Page 558

Multidisciplinary team of materials physicists and geophysicists combine theoretical predictions, simulations, and seismic tomography to find spin transition in the Earth’s mantle.

The interior of the Earth is a mystery, especially at greater depths (660 km). Researchers only have seismic tomographic images of this region and, to interpret them, they need to calculate seismic (acoustic) velocities in minerals at high pressures and temperatures. With those calculations, they can create 3D velocity maps and figure out the mineralogy and temperature of the observed regions. When a phase transition occurs in a mineral, such as a crystal structure change under pressure, scientists observe a velocity change, usually a sharp seismic velocity discontinuity.

In 2,003 scientists observed in a lab a novel type of phase change in minerals — a spin change in iron in ferropericlase, the second most abundant component of the Earth’s lower mantle. A spin change, or spin crossover, can happen in minerals like ferropericlase under an external stimulus, such as pressure or temperature. Over the next few years, experimental and theoretical groups confirmed this phase change in both ferropericlase and bridgmanite, the most abundant phase of the lower mantle. But no one was quite sure why or where this was happening.

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Scientists just broke the record for the coldest temperature ever measured in a lab: They achieved the bone-chilling temperature of 38 trillionths of a degree above-273.15 Celsius by dropping magnetized gas 393 feet (120 meters) down a tower.

The team of German researchers was investigating the quantum properties of a so-called fifth state of matter: Bose-Einstein condensate (BEC), a derivative of gas that exists only under ultra-cold conditions. While in the BEC phase, matter itself begins to behave like one large atom, making it an especially appealing subject for quantum physicists who are interested in the mechanics of subatomic particles.

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Researchers at Delft University of Technology have found a new way to cool radio waves all the way down to their quantum ground state. To do so, they used circuits that employ an analog of the so-called laser cooling technique that is frequently used to cool atomic samples. The device used a recently developed technique the researchers call photon pressure coupling, which is predicted to be of use in detecting ultra-weak magnetic resonance (MRI) signals or for quantum-sensing applications that can help the search for dark matter. The results have been published in Science Advances.

The radio waves we usually encounter in our daily lives, such as those that we listen to in our car or those that send signals to our baby monitors in our house, are hot: they contain noise that comes from the random motion of the in the things they are emitted from and even in the antenna you are using to listen to them. This is one of the reasons why you hear static when you tune the radio in your car to a frequency that has no .

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Oct. 13 2021 — In 1,998 researchers including Mark Kubinec of UC Berkeley performed one of the first simple quantum computations using individual molecules. They used pulses of radio waves to flip the spins of two nuclei in a molecule, with each spin’s “up” or “down” orientation storing information in the way that a “0” or “1” state stores information in a classical data bit. In those early days of quantum computers, the combined orientation of the two nuclei – that is, the molecule’s quantum state – could only be preserved for brief periods in specially tuned environments. In other words, the system quickly lost its coherence. Control over quantum coherence is the missing step to building scalable quantum computers.

Now, researchers are developing new pathways to create and protect quantum coherence. Doing so will enable exquisitely sensitive measurement and information processing devices that function at ambient or even extreme conditions. In 2,018 Joel Moore, a senior faculty scientist at Lawrence Berkeley National Laboratory (Berkeley Lab) and professor at UC Berkeley, secured funds from the Department of Energy to create and lead an Energy Frontier Research Center (EFRC) – called the Center for Novel Pathways to Quantum Coherence in Materials (NPQC) – to further those efforts. “The EFRCs are an important tool for DOE to enable focused inter-institutional collaborations to make rapid progress on forefront science problems that are beyond the scope of individual investigators,” said Moore.

Through the NPQC, scientists from Berkeley Lab, UC Berkeley, UC Santa Barbara, Argonne National Laboratory, and Columbia University are leading the way to understand and manipulate coherence in a variety of solid-state systems. Their threefold approach focuses on developing novel platforms for quantum sensing; designing two-dimensional materials that host complex quantum states; and exploring ways to precisely control a material’s electronic and magnetic properties via quantum processes. The solution to these problems lies within the materials science community. Developing the ability to manipulate coherence in realistic environments requires in-depth understanding of materials that could provide alternate quantum bit (or “qubit”), sensing, or optical technologies.

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Scientists are getting closer to being able to spot Hawking radiation – that elusive thermal radiation thought to be produced by a black hole’s event horizon. Just understanding the concept of this radiation is tricky though, let alone finding it.

A new proposal suggests creating a special kind of quantum circuit to act as a ‘black hole laser’, essentially simulating some of the properties of a black hole. As with previous studies, the idea is that experts can observe and study Hawking radiation without actually having to look at any real black holes.

The basic principle is relatively straightforward. Black holes are objects that warp spacetime so much, not even a wave of light can escape. Swap spacetime for some other material (such as water) and make it flow quickly enough so that waves passing through are too slow to escape, and you’ve got yourself a fairly rudimentary model.

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The interior of the Earth is a mystery, especially at greater depths (660 km). Researchers only have seismic tomographic images of this region and, to interpret them, they need to calculate seismic (acoustic) velocities in minerals at high pressures and temperatures. With those calculations, they can create 3D velocity maps and figure out the mineralogy and temperature of the observed regions. When a phase transition occurs in a mineral, such as a crystal structure change under pressure, scientists observe a velocity change, usually a sharp seismic velocity discontinuity.

In 2,003 scientists observed in a lab a novel type of phase change in minerals—a spin change in iron in ferropericlase, the second most abundant component of the Earth’s lower mantle. A spin change, or spin crossover, can happen in minerals like ferropericlase under an external stimulus, such as pressure or temperature. Over the next few years, experimental and theoretical groups confirmed this phase change in both ferropericlase and bridgmanite, the most abundant phase of the lower mantle. But no one was quite sure why or where this was happening.

In 2,006 Columbia Engineering Professor Renata Wentzcovitch published her first paper on ferropericlase, providing a theory for the spin crossover in this mineral. Her theory suggested it happened across a thousand kilometers in the lower mantle. Since then, Wentzcovitch, who is a professor in the and applied mathematics department, earth and environmental sciences, and Lamont-Doherty Earth Observatory at Columbia University, has published 13 papers with her group on this topic, investigating velocities in every possible situation of the spin crossover in ferropericlase and bridgmanite, and predicting properties of these minerals throughout this crossover. In 2,014 Wenzcovitch, whose research focuses on computational quantum mechanical studies of materials at extreme conditions, in particular planetary materials predicted how this spin change phenomenon could be detected in seismic tomographic images, but seismologists still could not see it.

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Quantum technology typically employs qubits (quantum bits) consisting of, for example, single electrons, photons or atoms. A group of TU Delft researchers has now demonstrated the ability to teleport an arbitrary qubit state from a single photon onto an optomechanical device—consisting of a mechanical structure comprising billions of atoms. Their breakthrough research, now published in Nature Photonics, enables real-world applications such as quantum internet repeater nodes while also allowing quantum mechanics itself to be studied in new ways.

Quantum optomechanics

The field of quantum optomechanics uses optical means to control mechanical motion in the quantum regime. The first quantum effects in microscale mechanical devices were demonstrated about ten years ago. Focused efforts have since resulted in entangled states between optomechanical devices as well as demonstrations of an optomechanical quantum memory. Now, the group of Simon Gröblacher, of the Kavli Institute of Nanoscience and the Department of Quantum Nanoscience at Delft University of Technology, in collaboration with researchers from the University of Campinas in Brazil, has shown the first successful teleportation of an arbitrary optical qubit state onto a micromechanical quantum memory.

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A Japanese startup at CES is claiming to have solved one of the biggest problems in medical technology: Noninvasive continuous glucose monitoring. Quantum Operation Inc, exhibiting at the virtual show, says that its prototype wearable can accurately measure blood sugar from the wrist. Looking like a knock-off Apple Watch, the prototype crams in a small spectrometer which is used to scan the blood to measure for glucose. Quantum’s pitch adds that the watch is also capable of reading other vital signs, including heart rate and ECG.

The company says that its secret sauce is in its patented spectroscopy materials which are built into the watch and its band. To use it, the wearer simply needs to slide the watch on and activate the monitoring from the menu, and after around 20 seconds, the data is displayed. Quantum says that it expects to sell its hardware to insurers and healthcare providers, as well as building a big data platform to collect and examine the vast trove of information generated by patients wearing the device.

Quantum Operation supplied a sampling of its data compared to that made by a commercial monitor, the FreeStyle Libre. And, at this point, there does seem to be a noticeable amount of variation between the wearable and the Libre. That, for now, may be a deal breaker for those who rely upon accurate blood glucose readings to determine their insulin dosage.

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