Physicists prove quantum mechanics sets a speed limit on reaching equilibrium

[Jonathan_Repetto]

How quickly can a hot object and a cold object reach the same temperature? Physicists have shown that quantum mechanics puts a universal limit on that speed. Interesting Engineering's Ameya Paleja reports on the work, published in Nature Physics by researchers from the Austrian Academy of Sciences, the Autonomous University of Barcelona and the University of Geneva

The team treated thermalisation, the process of reaching equilibrium, within a general quantum information framework. They then tested the result on a theoretical model made of quantum particles

The striking finding is how simple the limit is. It depends only on temperature, the reduced Planck constant and the Boltzmann constant. It does not depend on how complicated the surrounding environment is, which makes it a fully general rule

When temperature differences are small, the system's two lowest energy states set the rate of thermalisation. The authors suggest the result matters for quantum computing and quantum sensing, where controlling heat and noise is crucial

Results like this connect thermodynamics and quantum information in a neat way. Quantum computers have to be kept extremely cold, and knowing the fundamental limits on cooling and heating helps engineers. It is a nice piece of fundamental physics with practical relevance

Do universal limits like this help quantum engineers in practice? And are thermodynamics and quantum information becoming one field?

Scientists find quantum link in how fast systems reach thermal balanceinterestingengineering.com

[Luca73]

Universal results are rare in messy many body systems. This one deserves attention. Geneva and Vienna have strong foundations groups. Foundations research often looks abstract until it suddenly matters

[Runner79]

Two lowest energy states controlling the rate is intuitive. Small temperature gaps only excite the bottom of the spectrum. Nice that the maths confirms it. Simple results often hide deep physics underneath