Abstract
High-precision low-temperature thermometry is a challenge for experimental quantum physics and quantum sensing. Here we consider a thermometer modeled by a dynamically-controlled multilevel quantum probe in contact with a bath. Dynamical control in the form of periodic modulation of the energy-level spacings of the quantum probe can dramatically increase the maximum accuracy bound of low-temperatures estimation, by maximizing the relevant quantum Fisher information. As opposed to the diverging relative error bound at low temperatures in conventional quantum thermometry, periodic modulation of the probe allows for low-temperature thermometry with temperature-independent relative error bound. The proposed approach may find diverse applications related to precise probing of the temperature of many-body quantum systems in condensed matter and ultracold gases, as well as in different branches of quantum metrology beyond thermometry, for example in precise probing of different Hamiltonian parameters in many-body quantum critical systems.
Highlights
High-precision low-temperature thermometry is a challenge for experimental quantum physics and quantum sensing
Precise probing of quantum systems is one of the keys to progress in diverse quantum technologies, including quantum metrology[1,2,3], quantum information processing (QIP)[4], and quantum many-body manipulations[5]
The maximum amount of information obtained on a parameter of a quantum system is quantified by the quantum Fisher information (QFI), which depends on the extent to which the state of the system changes for an infinitesimal change in the estimated parameter[6,7,8,9,10]
Summary
High-precision low-temperature thermometry is a challenge for experimental quantum physics and quantum sensing. Dynamical control in the form of periodic modulation of the energy-level spacings of the quantum probe can dramatically increase the maximum accuracy bound of low-temperatures estimation, by maximizing the relevant quantum Fisher information. We propose the synthesis of two concepts: quantum thermometry[8,12,14,15,16,17,18,19,20,21,22] and temporally periodic dynamical control that has been originally developed for decoherence suppression in QIP23–27 We show that such control can strongly increase the QFI that determines the precision bound of temperature measurement, at temperatures approaching absolute zero. Dynamical control may allow theese thermometers to accurately estimate a broad range of temperatures
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