Quantum Thermal Machine as a Thermometer

Abstract

We propose the use of a quantum thermal machine for low-temperature thermometry. A hot thermal reservoir coupled to the machine allows for simultaneously cooling the sample while determining its temperature without knowing the model-dependent coupling constants. In its most simple form, the proposed scheme works for all thermal machines that perform at Otto efficiency and can reach Carnot efficiency. We consider a circuit QED implementation that allows for precise thermometry down to ∼15 mK with realistic parameters. Based on the quantum Fisher information, this is close to the optimal achievable performance. This implementation demonstrates that our proposal is particularly promising in systems where thermalization between different components of an experimental setup cannot be guaranteed.

Boosting the performance of small autonomous refrigerators via common environmental effects

“…Furthermore, we find that whenever α approaches 1, the effect of the interaction Hamiltonian between the three fridge qubits in equation (2) becomes superflous for the function of the fridge. This can be already understood from the availability of cycles like the one pointed in (21). Therefore, using the collective couplings to the environment reported here (equation (5)) becomes an alternative way to realize the fridge without the need of the three-body interaction in equation (2).…”

“…since now the latter transition is allowed by the common reservoir. Therefore the previous 6 cycles of length 4 are combined for α>0 with 6 new cycles of length 3 as the one in (21), which may accomplish the task of cooling more quickly.…”

“…They provide both theoretical insights and proposals for implementations in the laboratory, some of which are recently seeing light [13][14][15][16][17]. Furthermore, quantum thermal machines may be of practical importance in biological processes [18,19], for measuring time [20] or small temperatures [21], as well as producing quantum resources such as entanglement [22] or coherence [23].…”

Quantum magnetometry using two-stroke thermal machines

“…Our technique is therefore reminiscent of the Wheatstone bridge setup where the error in measuring small electrical resistances can be significantly reduced through an indirect measurement of a higher resistance. A similar technique of using a quantum thermal machine as a thermometer is also presented in [46]. Further, such enhancements in precision using the Wheatstone bridge principle have also been demonstrated in a number of other measurement devices, e.g.…”

“…In this work, we propose using a quantum thermal machine as a quantum probe. Quantum thermal machines are of great importance in the fields of quantum technologies and quantum thermodynamics [38][39][40][41][42][43][44][45]; at the same time, they were also shown to be beneficial for high-precision thermometry [46]. We present the possibility of using a quantum heat machine [47] as a magnetometer to estimate weak magnetic fields with high accuracy.…”