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Entropy transfer from a quantum particle to a classical coherent light field



John Bartolotta, Simon Jager, Jarrod Reilly, Matthew Norcia, James K. Thompson, Graeme Smith, Murray Holland


In the eld of light-matter interactions, it is often assumed that a classical light field that interacts with a quantum particle remains almost unchanged and thus contains nearly no information about the manipulated particles. To investigate the validity of this assumption, we develop and theoretically analyze a simple Gedankenexperiment which involves the interaction of a coherent state with a quantum particle in an optical cavity. We quantify the resulting alteration of the light field by measuring the fidelity of its initial and equilibrium states. Using Bayesian inference, we demonstrate the information transfer through photon measurements. In addition, we employ the concepts of quantum entropy and mutual information to quantify the entropy transfer from the particle to the light field. In the weak coupling limit, we validate the usually assumed negligible alteration of the light field and entropy transfer. In the strong coupling limit, however, we observe that the information of the initial particle state can be fully encoded in the light field, even for large photon numbers. Nevertheless, we show that spontaneous emission is a sufficient mechanism for removing the entropy initially stored in the particle. Our analysis provides a deeper understanding of the entropy exchange between quantum matter and classical light.
Physical Review Research


coherent states, critical photon number, entropy removal, quantum optics


Bartolotta, J. , Jager, S. , Reilly, J. , Norcia, M. , Thompson, J. , Smith, G. and Holland, M. (2022), Entropy transfer from a quantum particle to a classical coherent light field, Physical Review Research, [online], (Accessed May 25, 2024)


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Created March 23, 2022, Updated November 29, 2022