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

:::info 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.

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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

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

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

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

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\ 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

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\ (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

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

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

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

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

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