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Using machine learning three groups, including researchers at IBM and DeepMind, have simulated atoms and small molecules more accurately than existing quantum chemistry methods. In separate papers on the arXiv preprint server the teams each use neural networks to represent wave functions of electrons that surround the molecules’ atoms. This wave function is the mathematical solution of the Schrödinger equation, which describes the probabilities of where electrons can be found around molecules. It offers the tantalising hope of ‘solving chemistry’ altogether, simulating reactions with complete accuracy. Normally that goal would require impractically large amounts of computing power. The new studies now offer a compromise of relatively high accuracy at a reasonable amount of processing power.

Each group only simulates simple systems, with ethene among the most complex, and they all emphasise that the approaches are at their very earliest stages. ‘If we’re able to understand how materials work at the most fundamental, atomic level, we could better design everything from photovoltaics to drug molecules,’ says James Spencer from DeepMind in London, UK. ‘While this work doesn’t achieve that quite yet, we think it’s a step in that direction.’

Two approaches appeared on arXiv just a few days apart in September 2019, both combining deep machine learning and Quantum Monte Carlo (QMC) methods. Researchers at DeepMind, part of the Alphabet group of companies that owns Google, and Imperial College London call theirs Fermi Net. They posted an updated preprint paper describing it in early March 2020.¹ Frank Noé’s team at the Free University of Berlin, Germany, calls its approach, which directly incorporates physical knowledge about wave functions, PauliNet.²

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Underwater quantum links are possible across 30 meters (100 feet) of turbulent water, scientists have shown. Such findings could help to one day secure quantum communications for submarines.

Quantum cryptography exploits the quantum properties of particles such as photons to help encrypt and decrypt messages in a theoretically unhackable way. Scientists worldwide are now endeavoring to develop satellite-based quantum communications networks for a global real-time quantum Internet.

Continue reading “Scientists Explore Underwater Quantum Links for Submarines” »

When people say quantum computing is “hot” right now they are most definitely talking metaphorically; today’s leading devices have to operate at close to absolute zero. Now two research groups have demonstrated technology that run s 15 times hotter, which could be a big step towards making the devices affordable and practical.

The reason quantum computers have to be run at such low temperatures is that the quantum states they rely on are incredibly fragile, and the slightest disturbance can cause the information encoded in them to be lost. To prevent this these devices are chilled to near absolute zero, where vibrations and thermal fluctuation are almost non existent.

Continue reading “New ‘Hot Qubits’ Let Quantum Computers Run 15X Warmer Than Before” »

John Martinis brought a long record of quantum computing breakthroughs when he joined Google in 2014. He quit after being reassigned to an advisory role.

Your phone’s GPS, the Wi-Fi in your house and communications on aircraft are all powered by radio-frequency, or RF, waves, which carry information from a transmitter at one point to a sensor at another. The sensors interpret this information in different ways. For example, a GPS sensor uses the angle at which it receives an RF wave to determine its own relative location. The more precisely it can measure the angle, the more accurately it can determine location.

In a new paper published in Physical Review Letters, University of Arizona engineering and optical sciences researchers, in collaboration with engineers from General Dynamics Mission Systems, demonstrate how a combination of two techniques—radio frequency photonics sensing and quantum metrology—can give sensor networks a previously unheard-of level of precision. The work involves transferring information from electrons to photons, then using quantum entanglement to increase the photons’ sensing capabilities.

“This quantum sensing paradigm could create opportunities to improve GPS systems, astronomy laboratories and biomedical imaging capabilities,” said Zheshen Zhang, assistant professor of materials science and engineering and optical sciences, and principal investigator of the university’s Quantum Information and Materials Group. “It could be used to improve the performance of any application that requires a network of sensors.”

O,.o circa 2007.

Theoretical physicists at the University of St. Andrews have created ‘incredible levitation effects’ by engineering the force of nature which normally causes objects to stick together by quantum force. By reversing this phenomenon, known as ‘Casimir force’, the scientists hope to solve the problem of tiny objects sticking together in existing novel nanomachines.

Professor Ulf Leonhardt and Dr Thomas Philbin of the University’s School of Physics & Astronomy believe that they can engineer the Casimir force of quantum physics to cause an object to repel rather than attract another in a vacuum.

Casimir force (discovered in 1948 and first measured in 1997) can be demonstrated in a gecko’s ability to stick to a surface with just one toe. However, it can cause practical problems in nanotechnology, and ways of preventing tiny objects from sticking to each other is the source of much interest.

This article reviews the history of digital computation, and investigates just how far the concept of computation can be taken. In particular, I address the question of whether the universe itself is in fact a giant computer, and if so, just what kind of computer it is. I will show that the universe can be regarded as a giant quantum computer. The quantum computational model of the universe explains a variety of observed phenomena not encompassed by the ordinary laws of physics. In particular, the model shows that the quantum computational universe automatically gives rise to a mix of randomness and order, and to both simple and complex systems.

O,.o circa 2016.

Nous appliquons les techniques de l’optique quantique micro-onde aux excitations collectives des spins d’une sphère macroscopique d’un isolant ferromagnétique. Nous mettons en évidence, dans la limite d’une unique excitation magnonique, le couplage fort entre un mode magnétostatique de la sphère et un mode d’une cavité micro-onde. En outre, nous avons ajouté un bit quantique supraconducteur à la cavité, ce qui permet de coupler ce bit quantique au mode de magnon, via l’échange virtuel d’un photon. Nous observons ainsi un anticroisement des fréquences de résonance du magnon et de la cavité. Cette plateforme hybride permet la création et la caratérisation d’états non classiques de magnons.

Two research groups say they’ve independently built quantum devices that can operate at temperatures above 1 Kelvin—15 times hotter than rival technologies can withstand.

The ability to work at higher temperatures is key to scaling up to the many qubits thought to be required for future commercial-grade quantum computers.

Continue reading “Quantum Computing Milestone: Researchers Compute With ‘Hot’ Silicon Qubits” »