A record-breaking experiment shows an enormous molecule is also both a particle and a wave—and that quantum effects don’t only apply at tiny scales.
Category: quantum physics – Page 725
In a new scientific paper, Google researchers claim for the first time to have demonstrated “quantum supremacy,” where a quantum computer outperforms a traditional one.
The news: According to a report in the Financial Times, a team of researchers from Google led by John Martinis have demonstrated quantum supremacy for the first time. This is the point at which a quantum computer is shown to be capable of performing a task that’s beyond the reach of even the most powerful conventional supercomputer. The claim appeared in a paper that was posted on a NASA website, but the publication was then taken down. Google did not respond to a request for comment from MIT Technology Review.
Why NASA? Google struck an agreement last year to use supercomputers available to NASA as benchmarks for its supremacy experiments. According to the Financial Times report, the paper said that Google’s quantum processor was able to perform a calculation in three minutes and 20 seconds that would take today’s most advanced supercomputer, known as Summit, around 10,000 years. In the paper, the researchers said that, to their knowledge, the experiment “marks the first computation that can only be performed on a quantum processor.”
Quantum speed up: Quantum machines are so powerful because they harness quantum bits, or qubits. Unlike classical bits, which are either a 1 or a 0, qubits can be in a kind of combination of both at the same time. Thanks to other quantum phenomena, which are described in our explainer here, quantum computers can crunch large amounts of data in parallel that conventional machines have to work through sequentially. Scientists have been working for years to demonstrate that the machines can definitively outperform conventional ones.
Google’s new quantum computer reportedly spends mere minutes on the tasks the world’s top supercomputers would need several millennia to perform. The media found out about this after NASA “accidentally” shared the firm’s research.
The software engineers at Google have built the world’s most powerful computer, the Financial Times and Fortune magazine reported on Friday, citing the company’s now-removed research paper. The paper is said to have been posted on a website hosted by NASA, which partners with Google, but later quietly taken down, without explanation.
Google and NASA have refused to comment on the matter. A source within the IT giant, however, told Fortune that NASA had “accidentally” published the paper before its team could verify its findings.
Theorists attribute the unexpectedly slow thermalization of cold atoms seen in recent experiments to an effect called quantum many-body scarring.
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Researchers still have some way to go before they can assemble enough quantum bits (qubits) to make a practical, large-scale quantum computer. But already the best prototypes, made up of several tens of qubits, are opening our eyes to new behavior in the quantum realm. Last year, a team from Harvard University and the Massachusetts Institute of Technology (MIT) unveiled a quantum “simulator” made up of a row of 51 interacting atoms [1]. Exciting the individual atoms in various patterns (Fig. 1), they discovered something unexpected: atoms in certain patterns took at least 10 times longer to relax towards thermal equilibrium than atoms in other patterns. Four groups of theorists have tried to make sense of this observation [2–6], in all cases attributing the slow thermalization to a never-before-seen effect called quantum many-body scarring.
Over the past few years, thermoelectric generators have become the focus of a growing number of studies, due to their ability to convert waste heat into electrical energy. Quantum dots, semiconductor crystals with distinctive conductive properties, could be good candidates for thermoelectric generation, as their discrete resonant levels provide excellent energy filters.
In a recent study, researchers at the University of Cambridge, in collaboration with colleagues in Madrid, Rochester, Duisburg and Sheffield, have experimentally demonstrated the potential of an autonomous nanoscale energy harvester based on resonant tunneling quantum dots. This harvester is based on previous research carried out by part of their team, who had proposed a three-terminal energy harvester based on two resonant-tunneling quantum dots with different energy levels.
The energy harvester device was realized at Cavendish Laboratory in Cambridge by a researcher called Gulzat Jaliel. The original theoretical proposal for the device, however, was introduced by Andrew Jordan in 2013, and the theoretical work behind the harvester was carried out by him in collaboration with renowned semiconductor physicist Markus Büttiker and a team of post-doctoral students in Geneva.
Quantum mechanics and the general theory of relativity form the bedrock of the current understanding of physics—yet the two theories don’t seem to work together. Physical phenomena rely on relationship of motion between the observed and the observer. Certain rules hold true across types of observed objects and those observing, but those rules tend to break down at the quantum level, where subatomic particles behave in strange ways.
An international team of researchers developed a unified framework that would account for this apparent break down between classical and quantum physics, and they put it to the test using a quantum satellite called Micius. They published their results ruling out one version of their theory on Sept 19th in Science.
Micius is part of a Chinese research project called Quantum Experiments at Space Scale (QUESS), in which researchers can examine the relationship with quantum and classical physics using light experiments. In this study, the researchers used the satellite to produce and measure two entangled particles.
Wave function represents the quantum state of an atom, including the position and movement states of the nucleus and electrons. For decades researchers have struggled to determine the exact wave function when analyzing a normal chemical molecule system, which has its nuclear position fixed and electrons spinning. Fixing wave function has proven problematic even with help from the Schrödinger equation.
Previous research in this field used a Slater-Jastrow Ansatz application of quantum Monte Carlo (QMC) methods, which takes a linear combination of Slater determinants and adds the Jastrow multiplicative term to capture the close-range correlations.
Now, a group of DeepMind researchers have brought QMC to a higher level with the Fermionic Neural Network — or Fermi Net — a neural network with more flexibility and higher accuracy. Fermi Net takes the electron information of the molecules or chemical systems as inputs and outputs their estimated wave functions, which can then be used to determine the energy states of the input chemical systems.
This could make zero point energy teleportation for spaceships for near I instant object transfer.
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