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Two different groups have tested a seemingly counter-intuitive property of the quantum world: That it’s possible to put a photon, a particle of light, in a superposition of states going forward and backward in time. This is not time travel and won’t lead to communicating with the past – but it is an intriguing demonstration of how time can be thought to work at a quantum level.

Unless you have a TARDIS or a DeLorean, time only flows in one direction (forward) for us. This annoying little fact that protects us from all sorts of paradoxes is called the arrow of time. It is believed to be related to the concept of entropy (which always increases in an isolated system like the universe) but it doesn’t seem to be as fundamental at the quantum level.

Instead, something that appears to be fundamental is the so-called CPT symmetry (charge, parity, and time reversal symmetry). This holds for all physical phenomena, and if a combination of two of them is violated (such as famously the CP violations) there ought to be a violation in time symmetry as well.

Quantum mechanics, the theory which rules the microworld of atoms and particles, certainly has the X factor. Unlike many other areas of physics, it is bizarre and counter-intuitive, which makes it dazzling and intriguing. When the 2022 Nobel prize in physics was awarded to Alain Aspect, John Clauser and Anton Zeilinger for research shedding light on quantum mechanics, it sparked excitement and discussion.

But debates about quantum mechanics —be they on chat forums, in the media or in science fiction—can often get muddled thanks to a number of persistent myths and misconceptions. Here are four.

face_with_colon_three circa 2017.

Chinese scientists have successfully sent information between entangled particles through sea water, the first time this type of quantum communication has been achieved underwater.

A team of researchers at Universität Heidelberg has built an early universe analog in their laboratory using chilled potassium atoms. In their paper published in the journal Nature, the group describes their simulator and how it might be used. Silke Weinfurtner, with the University of Nottingham, has published a News & Views piece in the same journal issue outlining the work done by the team in Germany.

Understanding what occurred during the first few moments after the Big Bang is difficult due to the lack of evidence left behind. That leaves astrophysicists with nothing but theory to describe what might have happened. To give credence to their theories, scientists have built models that theoretically represent the conditions being described. In this new effort, the researchers used a new approach to build a physical model in their laboratory to simulate conditions just after the Big Bang.

Beginning with the theory that that the Big Bang gave rise to an expanding universe, the researchers sought to create what they describe as a “quantum field simulator.” Since most theories suggest it was likely that the early universe was very cold, near absolute zero, the researchers created an environment that was very cold. They then added potassium atoms to represent the universe they were trying to simulate.

Placing a particle of light in a superposition so that it is travelling both forwards and backwards in time could prove useful for quantum computation.

IBM has unveiled ‘Osprey’, the successor to its Eagle system, featuring the highest ever qubit count for a quantum processor.

Beating the previous record of 127 qubits.

IBM unveiled its most powerful quantum computer to date at the IBM Summit 2022 on Wednesday. Named “Osprey,” the 433 qubit processor has the largest qubit count of any IBM processor and is triple the size of the company’s previously record-breaking 127-qubit Eagle processor.

“The new 433 qubit ‘Osprey’ processor brings us a step closer to the point where quantum computers will be used to tackle previously unsolvable problems,” said Dr. Darío Gil, senior vice president of IBM and Director of Research.

The scientists said their spacetime simulation “agrees very well with theory.”

A team of physicists used a “quantum field simulator” to simulate a tiny expanding universe made out of ultracold atoms, a report from VICE

Simulating spacetime.

Continue reading “Scientists use a quantum state of matter to simulate the early universe’s expansion” »

IBM plans to move into a more modular design for future quantum computers to allow for more flexibility and rapid scale-up of qubits.