The relaxation of a system to a steady state is a central point of interest in many attempts to advance control over the quantum world. In this paper, we consider control through instantaneous Gaussian unitary operations on the ubiquitous lossy channel, and find locally optimal conditions for the cooling and heating of a multimode Gaussian state subject to losses and possibly thermal noise. This is done by isolating the parameters that encode entropy and temperature and by deriving an equation for their evolution. This equation is in such a form that it grants clear insight into how relaxation may be helped by instantaneous quantum control. It is thus shown that squeezing is a crucial element in optimising the rate of change of entropic properties under these channels. Exact relaxation times for heating and cooling are derived, up to an arbitrarily small distance from the fixed point of the lossy channel with locally optimal strategies.
Hierarchies of Gaussian multimode entanglement from thermodynamic quantifiers
Harish-Chandra Research Institute, A CI of Homi Bhabha National Institute（哈里什-钱德拉研究所，霍米·巴巴国立学院成员机构）；NextQuantum Innovation Research Center, Department of Physics and Astronomy, Seoul National University（首尔大学物理与天文学系下一代量子创新研究中心）
Partner-mode overlap as a symplectic-invariant measure of correlations in Gaussian quantum field theories
Louisiana State University（路易斯安那州立大学）；University of Waterloo（滑铁卢大学）；Perimeter Institute for Theoretical Physics（珀米特理论物理研究所）；University of Helsinki（赫尔辛基大学）；Kyushu University（九州大学）
Even Odd Splitting of the Gaussian Quantum Fisher Information: From Symplectic Geometry to Metrology
Center for Macroscopic Quantum States (bigQ), Department of Physics, Technical University of Denmark（丹麦技术大学物理系宏观量子态中心）；QMill Oy（QMill公司）；Institute for Theoretical Physics, Leibniz Institute of Hannover（汉诺威莱布尼茨理论物理研究所）；Institute for Physics and Astronomy, TU Berlin（柏林工业大学物理与天文学研究所）；School of Physics, Korea Institute for Advanced Study（韩国高等研究院物理学院）；Department of Chemical and Biological Physics, Weizmann Institute of Science（魏茨曼科学研究所化学与生物物理系）
