Quantum light engine links atom-photon thermodynamics to classical physics
What is heat, and what is useful work if a machine consists only of an atom and light particles? In modern quantum technologies, this kind of question connects thermodynamics with quantum physics. Researchers at the University of Basel, Switzerland, have developed a theoretical approach that can reconcile both theories.
Researchers at the University of Basel have devised a theoretical approach that bridges the gap between quantum thermodynamics and classical physics. Traditionally, thermodynamics deals with large-scale systems, such as steam engines, while quantum physics explores the behavior of atoms and subatomic particles. However, modern quantum technologies often involve tiny systems consisting of atoms and light particles, which can absorb, convert, and release energy.
The challenge lies in developing a theory that accurately describes these systems in both quantum and semiclassical limits. The semiclassical limit involves treating part of the system quantum mechanically and the other part classically. A recent study by researchers from the University of Basel, led by Professor Patrick Potts, presents a method that addresses this challenge. Their calculations focus on an atom placed in a cavity between two mirrors, where it can interact with light particles.
In this scenario, a laser continuously injects additional photons into the cavity, while some light escapes through partially reflecting mirrors. This setup serves as a model for studying open quantum systems, where the atom functions as a miniature heat engine. The researchers found that not all the light particles escaping from the cavity should be considered waste heat in thermodynamic terms. Instead, a portion of their energy can still be utilized to perform useful work on another quantum system.
By treating the light classically in the semiclassical limit, the researchers were able to differentiate between usable energy and disordered heat more effectively than using conventional methods that treat all emitted energy as heat. Their calculations also predicted that quantum effects lead to a reduction in fluctuations of the light particles, which is crucial for applications in quantum technologies.
For instance, this phenomenon can enable the creation of specific light states with high precision for measurements in quantum metrology.
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