Light and matter can remain at separate temperatures even while interacting with each other for long periods, according to new research that could help scale up an emerging quantum computing approach in which photons and atoms play a central role.
In a theoretical study published in Physical Review Letters, a University at Buffalo-led team reports that interacting photons and atoms don’t always rapidly reach thermal equilibrium as expected.
Thermal equilibrium is the process by which interacting particles exchange energy before settling at the same temperature, and it typically happens quickly when trapped light repeatedly interacts with matter. Under the right circumstances, however, physicists found that photons and atoms can instead settle at different—and in some cases opposite—temperatures for extended periods.
Implications for quantum computing
These so-called prethermal states are fleeting on human timescales, but they can last long enough to matter for neutral-atom quantum computers, which rely on interactions between photons and atoms to store and process information.
“Thermal equilibrium alters quantum properties, effectively erasing the very information those properties represent in a quantum computer,” says the study’s lead author, Jamir Marino, Ph.D., assistant professor of physics in the UB College of Arts and Sciences. “So delaying thermal equilibrium between photons and atoms—even for a matter of milliseconds—offers a temporal window to preserve and process useful quantum behavior.”
All quantum computers store and process information using qubits—the most basic units of quantum information and analogous to the binary bits used in classical computers. While classical bits can exist either as a 1 or a 0, qubits have the ability to exist in a superposition of two states at once, allowing for infinitely more complex calculations.
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