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.
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.
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.
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.
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.