Quantum Critical Engine at Finite Temperatures: Many Body Quantum Otto Cycle

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18 Sept 2024

Authors:

(1) Revathy B S, Raman Research Institute, Bengaluru, 560080, Karnataka, India and Corresponding author;

(2) Victor Mukherjee, Department of Physical Sciences, Indian Institute of Science Education and Research Berhampur, Berhampur, 760010, Odisha, India;

(3) Uma Divakaran, Department of Physics, Indian Institute of Technology Palakkad, Palakkad, 678623, Kerala, India.

Abstract and 1 Introduction

2 Free fermionic model

3 Many body quantum Otto cycle

4 Universal scalings in work output

5 Transverse Ising model as working medium

6 Conclusion and References

3 Many body quantum Otto cycle

We now describe the quantum Otto cycle (QOC) which consist of four strokes (also shown in Fig.1):

Fig. 1 Schematic diagram of a quantum Otto cycle

(ii) Stroke B → C: The WM is disconnected from the hot bath and α is changed from α1 to α2 using the driving protocol,

The evolution being a unitary evolution is given by the von-Neumann equation of motion:

In this work, we shall focus on α2 = αc, the critical value, for the reasons that will be explained later.

(iii) Stroke C → D: The WM with α = α2 is next connected to the cold bath at a temperature TC till τC so that it reaches the thermal state at D given by

(iv) Stroke D → A: In this last stroke, the WM is disconnected from the cold bath, and α is changed back to α1 from α2 using

to reach A through unitary dynamics and thus the cycle repeats.

Energies at the end of each stroke i is calculated using the equation

We characterize the engine performance using the quantities efficiency and power which are computed as

This paper is available on arxiv under CC BY 4.0 DEED license.