Quantum thermometry in a squeezed thermal bath

Abstract

We address the dephasing dynamics of the quantum Fisher information for the process of quantum thermometry with probes coupled to squeezed thermal baths via the nondemolition interaction. We also calculate the upper bound for the parameter estimation and investigate how the optimal estimation is affected by the initial conditions and decoherence, particularly the squeezing parameters. Moreover, the feasibility of the optimal measurement of the temperature is discussed in detail. Then, the results are generalized for entangled probes and the multi-qubit scenarios for probing the temperature are analysed. Our results show that the squeezing can decrease the number of channel uses for optimal thermometry. Comparing different schemes for multi-qubit estimation, we find that an increase in the number of the qubits, interacting with the channel, does not necessarily vary the precision of estimating the temperature. Besides, we discuss the enhancement of the quantum thermometry using the parallel strategy and starting from the W state.

Environmental parameter estimation with the two-level atom probes

“…At present, many schemes have been proposed to improve the estimation precision of the temperature with quantum estimation theory, such as a ring-structure system interacting with the bath, [40] twolevel atoms transported through an optical cavity, [41] a uniformly accelerated two-level atom coupled to a massless scalar field in the Minkowski vacuum, [42] and the probe system embedded into the structured reservoir. [43][44][45][46][47] However, the model that the two-level system (qubit) is directly immersed in a ther-mal reservoir has not been utilized for the temperature estimation. In addition, several researchers have reported that the squeezed state or reservoir has the potential to protect the nonclassical effects of the quantum system [48] and improve the accuracy of phase estimation.…”

Stochastic Collisional Quantum Thermometry

“…The thermometric precision of a probe in equilibrium with the sample is limited by the thermal Cramer–Rao bound, which is inversely proportional to the heat capacity, C , of the thermometer: . However, quantum systems have the additional freedom to exploit resources, such as entanglement [ 8 , 9 ] and coherence [ 10 , 11 , 12 ], to gain an advantage over their classical counterpart [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. By making use of these resources, along with collective measurements on multiple probes, it is possible to surpass the scaling of the Cramer–Rao bound.…”

Estimating energy levels of a three-level atom in single and multi-parameter metrological schemes

“…Conversely, the technical one is mostly represented by the accidental error, because of out-ofcontrol imperfections in the measurement process. Since quantum mechanics is the most fundamental, predictive, and successful theory describing small scale phenomena, an investigation of the measurement process as well as the ultimate achievable precision bounds has to be done under the light of such theory [1][2][3][4][5][6][7][8]. In fact, on the one hand, quantum theory determines fundamental limits on the estimate precision.…”