Enhanced precision of low-temperature quantum thermometry via dynamical control

Abstract

Precise probing of quantum systems is one of the keys to progress in diverse quantum technologies, includingquantum metrology, quantum information processing and quantum many-body manipulations. We consider athermometer modelled by a dynamically-controlled multilevel quantum system in contact with a thermal bath.As opposed to the diverging relative error near absolute zero of previously suggested thermometers, dynamicalcontrol of the probe enables high-precision thermometry close to the absolute zero, with a constant (temperature-independent) relative error bound, by maximizing its quantum Fisher information. The proposed approach may finddiverse applications related to precise probing of the temperatures of many-body quantum systems in condensedmatter and ultracold gases, as well as in different branches of quantum metrology beyond thermometry, forexample in precise probing of different Hamiltonian parameters in many-body quantum critical systems.