Few-qubit quantum refrigerator for cooling a multi-qubit system

Onat Arısoy,Özgür E Müstecaplıoğlu

doi:10.1038/s41598-021-92258-0

Onat Arısoy, Özgür E Müstecaplıoğlu

Open Access

https://doi.org/10.1038/s41598-021-92258-0

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Abstract

We propose to use a few-qubit system as a compact quantum refrigerator for cooling an interacting multi-qubit system. We specifically consider a central qubit coupled to N ancilla qubits in a so-called spin-star model to be used as refrigerant by means of short interactions with a many-qubit system to be cooled. We first show that if the interaction between the qubits is of the longitudinal and ferromagnetic Ising model form, the central qubit is colder than the environment. We summarize how preparing the refrigerant qubits using the spin-star model paves the way for the cooling of a many-qubit system by means of a collisional route to thermalization. We discuss a simple refrigeration cycle, considering the operation cost and cooling efficiency, which can be controlled by N and the qubit–qubit interaction strength. Besides, bounds on the achievable temperature are established. Such few-qubit compact quantum refrigerators can be significant to reduce dimensions of quantum technology applications, can be easy to integrate into all-qubit systems, and can increase the speed and power of quantum computing and thermal devices.

Highlights

We propose to use a few-qubit system as a compact quantum refrigerator for cooling an interacting multi-qubit system
We focus our range of parameters on this particular case, though our generic models, exact analytical results, and general conclusions apply a broader class of physical systems
Based on our numerical results, we can conclude that the cooperative cooling with ancilla qubits always increases the efficiency but it significantly increases the minimum achievable effective temperature especially for high numbers of ancilla qubits compared to the case where only the central qubit is used for cooling of the target many-body system

Summary

Introduction

We propose to use a few-qubit system as a compact quantum refrigerator for cooling an interacting multi-qubit system. We study the energy cost and efficiency of preparing the refrigerant qubits (system B) by considering a cyclic transformation of the whole spin-star system (system A) in a single thermal environment whose interactions with system A are not controllable, in other words, these interactions cannot be switched off or have time dependence.

Results

Conclusion