2017/06/08 by Hui Dong, Da-wei Wang, Dong, Hui +5 · 1 citation
Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #FOS: Physical sciences #Quantum Gases (cond-mat.quant-gas) #Quantum Mechanics and Applications #Quantum Physics (quant-ph) #Statistical Mechanics and Entropy #cond-mat.quant-gas #quant-ph
paper · pdf · doi:10.48550/arxiv.1706.02636
5 pages, 4 figures
arxiv created 2017/06/08 · openalex publication_date 2017/06/08 · arxiv updated 2017/06/09 · openalex created_date 2017/06/15 · openalex updated_date 2026/07/28
Irreversible processes are frequently adopted to account for the entropy increase in classical thermodynamics. However, the corresponding physical origins are not always clear, e.g. in a free expansion process, a typical model in textbooks. In this letter, we study the entropy change during free expansion for a particle with the thermal de Broglie wavelength (λT) in a one-dimensional square trap with size L. By solely including quantum dephasing as an irreversible process, we recover classical result of entropy increase in the classical region (L≫λT), while predict prominent discrepancies in the quantum region (L≪λT) because of non-equilibrium feature of trapped atoms after expansion. It is interesting to notice that the dephasing, though absent in classical system, is critical to clarify mysteries in classical thermodynamics.