Physicists have made light move backwards and forwards in time. Scientists could benefit from the new technique.
Two teams of physicists have achieved a "quantum time flip" by splitting a packet of light using a special optical crystal.
The counterintuitive rules that govern the behavior of the small result in the effect. The first principle of quantum superposition is that minuscule particles can exist in many different states at the same time. Any system containing particles will obey the same physical laws even if the particles' charges, spatial coordinates and movements are flipped as if through a mirror.
You should know a lot about quantum physics.
The physicists created a photon that traveled along and against the arrow of time. 2 (opens in new tab) on the preprint server arXiv, meaning the findings have yet to be peer reviewed.
A physicist at the University of Vienna, Teodor Strmberg, was the first author on one of the arrow of time concepts. Many of the fundamental laws of physics don't have a preferred time direction and this is in tension with that.
The second law of thermodynamics states that the system's ability to function must increase. One of the few quantities in physics that sets time in a specific direction is thearrow of time.
It's easier to mix ingredients if disorder grows in the universe. Our sense of time is tied to the disorder. There is a famous scene in Kurt Vonnegut's novel "Slaughterhouse-Five" in which bullets are sucked from wounded men while fires are shrunk and bombs are stacked in neat rows.
As a statistical concept, it doesn't apply to single particles The up to 1 billion interactions per second that take place inside the world's largest atom smasher are just some of the observations scientists have made. Particles that seem to move forward in time are not the same as those that seem to move backwards in time. Antimatter doesn't move backwards in time, it just behaves as if it is following an arrow of time to normal matter.
Superposition is one of the factors at play. The most famous demonstration of quantum superposition is Schrdinger's cat, a thought experiment in which a cat is placed inside a sealed box and poisoned with a radioactive substance. It is not possible to tell what happened to the cat until the box is opened and the outcome observed.
The ability to exist in both forward and backward time states at the same time is difficult to observe. Both teams created similar experiments to split a photon along a path through a crystal. The superposed photon moved on one path through the crystal as normal, but another path was configured to change the photon's direction in order to travel back in time.
The team used a number of experiments to measure the photon polarization. If the photon had been split, they found a quantum interference pattern, a pattern of light and dark stripes.
Strmberg said that the superposition of processes is similar to an object spinning clockwise and counter-clockwise. The researchers created their time-flipped photon out of intellectual curiosity, but follow-up experiments show that time flips can be coupled with logic gates to enable simultaneous computation in either direction, opening the way for quantum processors with greatly enhanced processing power.
The work gives rise to theoretical possibilities. A future theory of quantum gravity, which would unite general relativity and quantum mechanics, should include particles of mixed time orientations like the one in this experiment.
"Our experiment is a simulation of exotic scenarios where a photon might evolve forward and backward in time," said Giulio Chiribella, a physicist at the University of Oxford. "What we do is an example of an experiment that mimics exotic physics, such as the physics of black holes or time travel."
All Rights Reserved © 2024
