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The central principle of superconductivity is that electrons form pairs. But can they also condense into foursomes? Recent findings have suggested they can, and a physicist at KTH Royal Institute of Technology today published the first experimental evidence of this quadrupling effect and the mechanism by which this state of matter occurs.

Reporting today in Nature Physics, Professor Egor Babaev and collaborators presented evidence of fermion quadrupling in a series of experimental measurements on the iron-based material, Ba_1−x K_x Fe₂As₂. The results follow nearly 20 years after Babaev first predicted this kind of phenomenon, and eight years after he published a paper predicting that it could occur in the material.

The pairing of electrons enables the quantum state of superconductivity, a zero-resistance state of conductivity which is used in MRI scanners and quantum computing. It occurs within a material as a result of two electrons bonding rather than repelling each other, as they would in a vacuum. The phenomenon was first described in a theory by, Leon Cooper, John Bardeen and John Schrieffer, whose work was awarded the Nobel Prize in 1972.

The central principle of superconductivity is that electrons form pairs. But can they also condense into foursomes? Recent findings have suggested they can, and a physicist at KTH Royal Institute of Technology today published the first experimental evidence of this quadrupling effect and the mechanism by which this state of matter occurs.

Reporting in Nature Physics, Professor Egor Babaev and collaborators presented evidence of fermion quadrupling in a series of experimental measurements on the iron-based material, Ba1−xKxFe2As2. The results follow nearly 20 years after Babaev first predicted this kind of phenomenon, and eight years after he published a paper predicting that it could occur in the material.

The pairing of electrons enables the quantum state of superconductivity, a zero-resistance state of conductivity which is used in MRI scanners and quantum computing. It occurs within a material as a result of two electrons bonding rather than repelling each other, as they would in a vacuum. The phenomenon was first described in a theory by, Leon Cooper, John Bardeen and John Schrieffer, whose work was awarded the Nobel Prize in 1972.

Convolutional neural networks running on quantum computers have generated significant buzz for their potential to analyze quantum data better than classical computers can. While a fundamental solvability problem known as “barren plateaus” has limited the application of these neural networks for large data sets, new research overcomes that Achilles heel with a rigorous proof that guarantees scalability.

“The way you construct a quantum neural network can lead to a barren plateau—or not,” said Marco Cerezo, co-author of the paper titled “Absence of Barren Plateaus in Quantum Convolutional Neural Networks,” published today by a Los Alamos National Laboratory team in Physical Review X. Cerezo is a physicist specializing in quantum computing, quantum machine learning, and quantum information at Los Alamos. “We proved the absence of barren plateaus for a special type of quantum neural network. Our work provides trainability guarantees for this architecture, meaning that one can generically train its parameters.”

As an artificial intelligence (AI) methodology, quantum convolutional neural networks are inspired by the visual cortex. As such, they involve a series of convolutional layers, or filters, interleaved with pooling layers that reduce the dimension of the data while keeping important features of a data set.

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.

Developing quantum-gravity technologies may elevate us to a “class A” civilization, capable of creating a baby universe.

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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.

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 atoms 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 radio station.

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.

Researchers propose quantum circuit black hole lasers to explore Hawking radiation.

Given the tricks GPT-3 had up its sleeve, it’s intriguing to wonder how the Megatron-Turing model may surprise us given that it’s three times larger.