Nonequilibrium thermodynamics and optimal cooling of a dilute atomic gas
| Autor: | Artur Widera, Steve Haupt, Daniel Mayer, Daniel Adam, Quentin Bouton, Tobias Lausch, Eric Lutz, Felix Schmidt |
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| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Physics
Statistical Mechanics (cond-mat.stat-mech) Entropy production Quantum Gases (cond-mat.quant-gas) Atomic Physics (physics.atom-ph) Non-equilibrium thermodynamics FOS: Physical sciences Statistical physics Physics::Atomic Physics Condensed Matter - Quantum Gases Measure (mathematics) Condensed Matter - Statistical Mechanics Physics - Atomic Physics |
| Popis: | Characterizing and optimizing thermodynamic processes far from equilibrium is a challenge. This is especially true for nanoscopic systems made of few particles. We here theoretically and experimentally investigate the nonequilibrium dynamics of a gas of few noninteracting Cesium atoms confined in a nonharmonic optical dipole trap and exposed to degenerate Raman sideband cooling pulses. We determine the axial phase-space distribution of the atoms after each Raman cooling pulse by tracing the evolution of the gas with position-resolved fluorescence imaging. We evaluate from it the entropy production and the statistical length between each cooling steps. A single Raman pulse leads to a nonequilibrium state that does not thermalize on its own, due to the absence of interparticle collisions. Thermalization may be achieved by combining free phase-space evolution and trains of cooling pulses. We minimize the entropy production to a target thermal state to specify the optimal spacing between a sequence of equally spaced pulses and achieve in this way optimal thermalization. We finally use the statistical length to verify a refined version of the second law of thermodynamics. Altogether, these findings provide a general, theoretical and experimental, framework to analyze and optimize far-from-equilibrium processes of few-particle systems. |
| Databáze: | OpenAIRE |
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