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Archive for the ‘quantum physics’ category: Page 476

Mar 14, 2021

PsiQuantum Preparing to Emerge From Stealth, Expect Commercial Quantum Computer by 2025

Posted by in categories: computing, finance, quantum physics

By the middle of the decade, the team from PsiQuantum will have a commercial quantum computer, according to the Financial Times. The founders are also indicating they are ready to emerge from stealth.

PsiQuantum has been mostly silent about its quantum computer development but with its scientific bench composed of leading UK physicists and nearly $300 million in venture capital funding, according to The Quantum Insider, that silence has been deafening.

Mar 14, 2021

Physics undergraduate proposes solution to quantum field theory problem

Posted by in categories: information science, particle physics, quantum physics

When physicists need to understand the quantum mechanics that describe how atomic clocks work, how your magnet sticks to your refrigerator or how particles flow through a superconductor, they use quantum field theories.

When they work through problems in quantum field theories, they do so in “imaginary” time, then map those simulations into real quantities. But traditionally, these simulations nearly always include uncertainties or unknown factors that could cause equation results to be “off.” So, when physicists interpret their simulation results into real quantities, these uncertainties amplify exponentially, making it difficult to have confidence that their results are as accurate as necessary.

Now, a pair of University of Michigan physicists have discovered that a set of functions called the Nevanlinna functions can tighten the interpretation step, showing that physicists may be able to overcome one of the major limitations of modern quantum simulation. The work, published in Physical Review Letters, was led by U-M physics undergraduate student Jiani Fei.

Mar 12, 2021

Photosynthesis tunes quantum-mechanical mixing of electronic and vibrational states to steer exciton energy transfer

Posted by in categories: biological, evolution, quantum physics

Photosynthetic light-harvesting antennae transfer energy toward reaction centers with high efficiency, but in high light or oxidative environments, the antennae divert energy to protect the photosynthetic apparatus. For a decade, quantum effects driven by vibronic coupling, where electronic and vibrational states couple, have been suggested to explain the energy transfer efficiency, but questions remain whether quantum effects are merely consequences of molecular systems. Here, we show evidence that biology tunes interpigment vibronic coupling, indicating that the quantum mechanism is operative in the efficient transfer regime and exploited by evolution for photoprotection. Specifically, the Fenna–Matthews–Olson complex uses redox-active cysteine residues to tune the resonance between its excitons and a pigment vibration to steer excess excitation toward a quenching site.

Photosynthetic species evolved to protect their light-harvesting apparatus from photoxidative damage driven by intracellular redox conditions or environmental conditions. The Fenna–Matthews–Olson (FMO) pigment–protein complex from green sulfur bacteria exhibits redox-dependent quenching behavior partially due to two internal cysteine residues. Here, we show evidence that a photosynthetic complex exploits the quantum mechanics of vibronic mixing to activate an oxidative photoprotective mechanism. We use two-dimensional electronic spectroscopy (2DES) to capture energy transfer dynamics in wild-type and cysteine-deficient FMO mutant proteins under both reducing and oxidizing conditions. Under reducing conditions, we find equal energy transfer through the exciton 4–1 and 4–2–1 pathways because the exciton 4–1 energy gap is vibronically coupled with a bacteriochlorophyll-a vibrational mode.

Mar 12, 2021

Physicists witness the bizarre birth of a ‘quasiparticle’

Posted by in categories: particle physics, quantum physics

Physicists exploring the quantum world watched the birth of a quasiparticle, shedding light on the strange behavior of these strange “fake particles.”

Mar 12, 2021

A new approach to directly testing quantum gravity

Posted by in category: quantum physics

Scientists have been trying to come up with a theory of quantum gravity for 100 years.


A team of physicists has proposed a clever plan to concoct a quantum theory of gravity: refine an age-old technique, and use it to probe the tiniest scales in the universe.

Mar 12, 2021

H.A.L.O. AI Completes XPRIZE Competition as Finalist with Groundbreaking Unification of Quantum Mechanics and Relativity

Posted by in categories: biotech/medical, quantum physics, robotics/AI

P.e.a.c.e!nc. is proud to announce the conclusion as finalists in the $500k Pandemic Response Challenge sponsored by Cognizant with Landmark AI Experiment.

Mar 11, 2021

Quantum computing: Honeywell just quadrupled the power of its computer

Posted by in categories: computing, quantum physics

Honeywell’s H1 quantum system has reached a record-high quantum volume.

Mar 11, 2021

Quantum Mischief Rewrites the Laws of Cause and Effect

Posted by in category: quantum physics

Spurred on by quantum experiments that scramble the ordering of causes and their effects, some physicists are figuring out how to abandon causality altogether.

Mar 11, 2021

Quantum Mechanics, the Chinese Room Experiment and the Limits of Understanding

Posted by in category: quantum physics

All of us, even physicists, often process information without really knowing what we’re doing.

Mar 10, 2021

Physicists Measure the Gravitational Force between the Smallest Masses Yet

Posted by in categories: computing, particle physics, quantum physics

But Aspelmeyer and his colleagues could not declare victory quite yet: they still had to rule out the possibility that the source mass modulation was generating other forces on the test mass that would oscillate at precisely the same frequency. Periodic rocking of the table supporting the experimental apparatus, caused by recoil from the barely visible motion of the source mass, was just one of a host of confounders the researchers had to carefully quantify. In the end, they found that all known nongravitational forces would be at least 10 times smaller than the gravitational interaction.

Reaching toward Quantum Scales

Aspelmeyer believes that an improved torsion pendulum will be sensitive to gravity from masses 5000 times smaller still—lighter than a single eyelash. His ultimate goal is to experimentally test the quantum nature of gravity, a question that has perplexed physicists for nearly a century. Quantum mechanics is one of the most successful and precisely tested theories in all of science: it describes everything from the behavior of subatomic particles to the semiconductor physics that makes modern computing possible. But attempts to develop a quantum theory of gravity have repeatedly been stymied by contradictory and nonsensical predictions.