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Even in the strange world of open quantum systems, the arrow of time is constantly pointing to the front – most of the time. New experiments conducted at the University of Washington in St. Louis compare the trajectories of the superconducting circuits called qubits, and find that they follow the second law of thermodynamics. The research is published on July 9 in the journal Letters of physical examination.
"When you look at a quantum system, measuring usually changes its behavior," said Kater Murch, an associate professor of physics in the field of arts and sciences. "Imagine lighting up a small particle, photons eventually pushing it and there is a dynamic associated with the measurement process alone.
"We wanted to know if this dynamic had anything to do with the arrow of time – the fact that entropy tends to increase over time."
In a related video (see link below), Murch asks, "Do quantum films look funny when you read them backwards?" He and his team, including physics graduate student and first paper author Patrick Harrington, asked this question at the lab, where their work is part of the new Center for Quantum Sensors.
"We examined microscopic films of the motion of a quantum system during the measurement and asked if the films seemed more likely when they were read or inverted; this comparison can be used to determine if the film was in a better state. Entropy increases or not, "said Murch. "We found that even at the microscopic scale, the second principle seems to be valid: the entropy generally increases.
"This increase is the result of what we are looking at.The process of creating the film apparently creates the arrow of time," he said.
The Murch research group focuses on understanding and controlling open quantum systems. While everyday objects obey the laws of classical mechanics, particles of light or matter follow the laws of quantum physics. But these particles are not easy to isolate and as soon as they interact with the outside world, they lose their quantum properties.
Murch is the 2018 recipient of a Cottrell Scholar Award and a CAREER Award from the National Science Foundation. The new research work presented in the video and publication is funded in part by his 2015 Alfred P. Sloan Fellowship.
Source of the story:
Material provided by University of Washington at St. Louis. Original written by Talia Ogliore. Note: Content can be changed for style and length.
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