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Category: computing – Page 392

Long-Lived Coherent Quantum States in a Superconducting Device for Quantum Information Technology

Scientists have been able to demonstrate for the first time that large numbers of quantum bits, or qubits, can be tuned to interact with each other while maintaining coherence for an unprecedentedly long time, in a programmable, solid-state superconducting processor. This breakthrough was made by researchers from Arizona State University and Zhejiang University in China, along with two theorists from the United Kingdom.

Previously, this was only possible in Rydberg atom.

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A series of buzzing, bee-like “loop-currents” could explain a recently discovered, never-before-seen phenomenon in a type of quantum material. The findings from researchers at the University of Colorado Boulder may one day help engineers to develop new kinds of devices, such as quantum sensors or the quantum equivalent of computer memory storage devices.

The quantum material in question is known by the chemical formula Mn3Si2Te6. But you could also call it “” because its manganese and tellurium atoms form a network of interlocking octahedra that look like the cells in a beehive.

Physicist Gang Cao and his colleagues at CU Boulder synthesized this molecular beehive in their lab in 2020, and they were in for a surprise: Under most circumstances, the material behaved a lot like an insulator. In other words, it didn’t allow electric currents to pass through it easily. When they exposed the honeycomb to magnetic fields in a certain way, however, it suddenly became millions of times less resistant to currents. It was almost as if the material had morphed from rubber into metal.

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The key to maximizing traditional or quantum computing speeds lies in our ability to understand how electrons behave in solids, and a collaboration between the University of Michigan and the University of Regensburg captured electron movement in attoseconds—the fastest speed yet.

Seeing move in increments of one quintillionth of a second could help push processing speeds up to a billion times faster than what is currently possible. In addition, the research offers a “game-changing” tool for the study of many-body physics.

“Your current computer’s processor operates in gigahertz, that’s one billionth of a second per operation,” said Mackillo Kira, U-M professor of electrical engineering and , who led the theoretical aspects of the study published in Nature. “In , that’s extremely slow because electrons within a computer chip collide trillions of times a second and each collision terminates the quantum computing cycle.

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In an interview published Tuesday with The Verge, Zuckerberg said VR, the technology he bet his entire $340 billion company on a year ago, is entering “the trough of disillusionment.” That’s a term folks in the tech industry like to use when excitement around a new technology drastically wanes.

His comments effectively place expectations for the success of the new Meta Quest Pro, which goes on sale Oct. 25, at next to zero. At the same time, Zuckerberg reiterated his belief that the metaverse will be the next iteration of computing after the smartphone — it’s just going to take a long time. Specifically, he told The Verge “it’s not going to be until later this decade” when metaverse gadgets like the Quest Pro will be “fully mature.”

But Meta isn’t selling headsets later this decade. It’s selling them now, and expecting technologists and software developers to invent compelling reasons to buy one.

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From superfast magnetic levitation trains and computer chips to magnetic resonance imaging (MRI) machines and particle accelerators, superconductors are electrifying various aspects of our life. Superconductivity is an interesting property that allows materials to transfer moving charges without any resistance, below a certain critical point. This implies that superconducting materials can transfer electrical energy in a highly efficient manner without loss in the form of heat, unlike many conventional conductors.

Almost two decades ago scientists discovered superconductivity in a —magnesium diboride, or MgB2. There has been a resurgence in the of popularity MgB2 due to its low cost, superior superconducting abilities, high critical current density (which means that compared to other materials, MgB2 remains a semiconductor even when larger amounts of electric current is passed through it), and trapped magnetic fields arising from strong pinning of the vortices—which are cylindrical current loops or tubes of magnetic flux that penetrate a superconductor.

The intermetallic MgB2 also allows adjustability of its properties. For instance, the critical current density values (Jc) of MgB2 can be improved by decreasing the grain size and increasing the number of grain boundaries. Such adjustability is not observed in conventional layered superconductors.

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In the past few years, a growing number of computer scientists have been exploring the idea of “metaverse,” an internet-based space where people would be able to virtually perform various everyday activities. The general idea is that, using virtual reality (VR) headsets or other technologies, people might be able to attend work meetings, meet friends, shop, attend events, or visit places, all within a 3D virtual environment.

While the metaverse has recently been the topic of much debate, accessing its 3D “virtual environments” often requires the use of expensive gear and devices, which can only be purchased by a relatively small amount of people. This unavoidably limits who might be able to access this virtual space.

Researchers at Beijing Institute of Technology and JD Explore Academy have recently created WOC, a 3D online chatroom that could be accessible to a broader range of people worldwide. To gain access to this chatroom, which was introduced in a paper pre-published on arXiv, users merely need a simple computer webcam or smartphone camera.

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Large glutamatergic, somatic synapses mediate temporally precise information transfer. In the ventral nucleus of the lateral lemniscus, an auditory brainstem nucleus, the signal of an excitatory large somatic synapse is sign inverted to generate rapid feedforward inhibition with high temporal acuity at sound onsets, a mechanism involved in the suppression of spurious frequency information. The mechanisms of the synaptically driven input–output functions in the ventral nucleus of the lateral lemniscus are not fully resolved. Here, we show in Mongolian gerbils of both sexes that, for stimulation frequencies up to 200 Hz, the EPSC kinetics together with short-term plasticity allow for faithful transmission with only a small increase in latency. Glutamatergic currents are exclusively mediated by AMPARs and NMDARs. Short-term plasticity is frequency-dependent and composed of an initial facilitation followed by depression. Physiologically relevant output generation is limited by the decrease in synaptic conductance through short-term plasticity (STP). At this endbulb synapse, STP acts as a low pass filter and increases the dynamic range of the conductance dependent input–output relation, while NMDAR signaling slightly increases the sensitivity of the input–output function. Our computational model shows that STP-mediated filtering limits the intensity dependence of the spike output, thus maintaining selectivity to sound transients. Our results highlight the interaction of cellular features that together give rise to the computations in the circuit.

SIGNIFICANCE STATEMENT Auditory information processing in the brainstem is a prerequisite for generating our auditory representation of the environment. Thereby, many processing steps rely on temporally precise filtering. Precise feedforward inhibition is a key motif in auditory brainstem processing and produced through sign inversion at several large somatic excitatory synapses. A particular feature of the ventral nucleus of the lateral lemniscus is to produce temporally precise onset inhibition with little temporal variance independent of sound intensity. Our cell-physiology and modeling data explain how the synaptic characteristics of different current components and their short-term plasticity are tuned to establish sound intensity-invariant onset inhibition that is crucial for filtering out spurious frequency information.

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A study led by researchers from the Institute Cajal of Spanish Research Council (CSIC) in Madrid, Spain in collaboration with the Bioengineering Department of George Mason University in Virginia, U.S. has updated one of the world’s largest databases on neuronal types, Hippocampome.org.

The study, which is published in the journal PLOS Biology, represents the most comprehensive mapping performed to date between recoded in vivo and identified . This major breakthrough may enable biologically meaningful computer modeling of the full neuronal circuit of the hippocampus, a region of the brain involved in memory function.

Circuits of the mammalian cerebral cortex are made up of two types of neurons: Excitatory neurons, which release a neurotransmitter called glutamate, and inhibitory neurons, which release GABA (gamma-aminobutanoic acid), the main inhibitor of the central nervous system. “A balanced dialogue between the ‘excitatory’ and ‘inhibitory’ activities is critical for . Identifying the contribution from the several types of excitatory and inhibitory cells is essential to better understand brain operation,” explains Liset Menendez de la Prida, the Director of the Laboratorio de Circuitos Neuronales at the Institute Cajal who leads the study at the CSIC.

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