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Category: quantum physics – Page 358

Companies could one day make superconductive quantum computer chips that function at room temperature thanks to a new material from researchers in the US. Ranga Dias from the University of Rochester and colleagues made a material superconductive at 21°C and pressures less than 1% of those used for existing high-temperature superconductors. ‘The most exciting part is the pressure,’ Dias tells Chemistry World. ‘Even I didn’t think this was possible.’

Together with Ashkan Salamat’s team at the University of Nevada, Las Vegas, the scientists say that electrical resistance in their nitrogen-doped lutetium hydride falls to zero at room temperature. Making room-temperature zero-resistance materials is a chemistry ‘holy grail’ and could fight climate change by reducing the 5% of electricity lost as heat while flowing through the grid.

However, Dias and Salamat’s team hasn’t been able to fully confirm the new material’s structure. As hydrogen atoms are so small they don’t easily diffract the x-rays used to work out the material’s composition. And this is an important reservation, considering the publisher of the team’s previous high-temperature superconductor paper retracted it.

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If you cool down low-density atomic gas to ultralow temperatures (−273°C), you get a new state of matter called the Bose-Einstein Condensate (BEC). A BEC has strongly coupled two-atom molecules behaving like a collective wave following quantum mechanics. If you reduce the pairing strength between them—for example, by increasing the magnetic field—the atoms form Cooper pairs according to Bardeen-Cooper-Schrieffer (BCS) theory (which won a Nobel Prize).

The process is called BCS-BEC crossover. And the theory forms the basis of superfluids and superconductors, materials that do not display viscosity or . Hiroyuki Tajima and his team from the University of Tokyo proposed a new method to distinguish current carriers in the BCS-BEC crossover. The key is in the fluctuations of current.

Electronic devices display images thanks to electrons moving in a conductor—aka single-particle current. Your device may heat up due to the resistance caused by collisions of electrons in the conductor that dissipate electric energy as heat. But superconductors show zero resistance to current flow, saving lots of energy. This is possible because of paired electrons, which would have otherwise repelled each other due to their negative charge. In other words, the current in superconductors is mainly due to the pair-tunneling transport involving moving paired-current carriers rather than a single-particle current carrier.

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Researchers have found a way to predict the behavior of many-body quantum systems coupled to their environment. The work represents a way to protect quantum information in quantum devices, which is crucial for real-world applications of quantum technology.

In a study published in Physical Review Letters, researchers at Aalto University in Finland and IAS Tsinghua University in China report a new way to predict how , such as groups of particles, behave when they are connected to the external environment. Usually, connecting a system such as a quantum computer to its environment creates decoherence and leaks, which ruin any information about what’s happening inside the system. Now, the researchers developed a technique that turns that problem into its a solution.

The research was carried out by Aalto doctoral researcher Guangze Chen under the supervision of Professor Jose Lado and in collaboration with Fei Song from IAS Tsinghua. Their approach combines techniques from two domains, quantum many-body physics and non-Hermitian quantum physics.

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By default, every quantum computer is going to be a hybrid that combines quantum and classical compute. Microsoft estimates that a quantum computer that will be able to help solve some of the world’s most pressing questions will require at least a million stable qubits. It’ll take massive classical compute power — which is really only available in the cloud — to control a machine like this and handle the error correction algorithms needed to keep it stable. Indeed, Microsoft estimates that to achieve the necessary fault tolerance, a quantum computer will need to be integrated with a peta-scale compute platform that can manage between 10 to 100 terabits per second of data moving between the quantum and classical machine. At the American Physical Society March Meeting in Las Vegas, Microsoft today is showing off some of the work it has been doing on enabling this and launching what it calls the “Integrated Hybrid” feature in Azure Quantum.

“With this Integrated Hybrid feature, you can start to use — within your quantum applications — classical code right alongside quantum code,” Krysta Svore, Microsoft’s VP of Advanced Quantum Development, told me. “It’s mixing that classical and quantum code together that unlocks new types, new styles of quantum algorithms, prototypes, sub routines, if you will, where you can control what you do to qubits based on classical information. This is a first in the industry.”

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With the rapid development of chatbots and other AI systems, questions about whether they will ever gain true understanding, become conscious, or even develop a feeling agency have become more pressing. When it comes to making sense of these qualities in humans, our ability for counterfactual thinking is key. The existence of alternative worlds where things happen differently, however, is not just an exercise in imagination – it’s a key prediction of quantum mechanics. Perhaps our brains are able to ponder how things could have been because in essence they are quantum computers, accessing information from alternative worlds, argues Tim Palmer.

Ask a chatbot “How many prime numbers are there?” and it will surely tell you that there are an infinite number. Ask the chatbot “How do we know?” and it will reply that there are many ways to show this, the original going back to the mathematician Euclid of ancient Greece. Ask the chatbot to describe Euclid’s proof and it will answer correctly [ii]. [ii.

Of course, the chatbot has got all this information from the internet. Additional software in the computer can check that each of the steps in Euclid’s proof is valid and hence can confirm that the proof is a good one. But the computer doesn’t understand the proof. Understanding is a kind of Aha! moment, when you see why the proof works, and why it wouldn’t work if a minor element in it was different (for example the proof in the footnotes doesn’t work if any number but 1 is added when creating the number Q). Chatbots don’t have Aha! moments, but we do. Why?

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Glass nanoparticles trapped by lasers in extreme vacuum are considered a promising platform for exploring the limits of the quantum world. Since the advent of quantum theory, the question at which sizes an object starts being described by the laws of quantum physics rather than the rules of classical physics has remained unanswered.

A team formed by Lukas Novotny (ETH Zurich), Markus Aspelmeyer (University of Vienna), Oriol Romero-Isart (University of Innsbruck), and Romain Quidant (Zurich) is attempting to answer precisely this question within the ERC-Synergy project Q-Xtreme. A crucial step on the way to this goal is to reduce the energy stored in the motion of the nanoparticle as much as possible, i.e. to cool the particle down to the so-called quantum ground-state.

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A 1960s nuclear research lab in the North of England will host a new quantum computing facility under plans drawn up by a Silicon Valley technology company.

PsiQuantum is to set up a research hub at the Daresbury Laboratory in Cheshire, using the facility’s state of the art cooling systems to develop its technology.

PsiQuantum, which is backed by BlackRock, Microsoft and Baillie Gifford, was set up by professors at the University of Bristol and Imperial College London but its founders moved to Silicon Valley in 2016 under advice from investors.

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I recently speculated on a toy model for scientific theology, with superintelligent God-like entities that live in the bare quantum vacuum. More speculations below.

This is not (yet) science — it’s far too vague and speculative to be called that — or theology. Call it science fiction (or “religion fiction” in the sense explored in my article “Religion Fiction Inspires Real Religion”) without the fiction. I guess I should write a science fiction story as a container for these speculations.

Therefore, I’ll often refer to superfluid vacuum theory (SVT) as “Cooper-Hofstadter theory” — a SVT that was featured in “The Big Bang Theory” TV show, of all things! Also, I guess Sheldon Cooper is more known than Leon Cooper.

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