Topological Josephson heat engine

Abstract

Topological superconductors represent a fruitful playing ground for fundamental research as well as for potential applications in fault-tolerant quantum computing. Especially Josephson junctions based on topological superconductors remain intensely studied, both theoretically and experimentally. The characteristic property of these junctions is their 4π-periodic ground-state fermion parity in the superconducting phase difference. Using such topological Josephson junctions, we introduce the concept of a topological Josephson heat engine. We discuss how this engine can be implemented as a Josephson–Stirling cycle in topological superconductors, thereby illustrating the potential of the intriguing and fruitful marriage between topology and coherent thermodynamics. It is shown that the Josephson–Stirling cycle constitutes a highly versatile thermodynamic machine with different modes of operation controlled by the cycle temperatures. Finally, the thermodynamic cycle reflects the hallmark 4π-periodicity of topological Josephson junctions and could therefore be envisioned as a complementary approach to test topological superconductivity.

Colloquium: Quantum heat transport in condensed matter systems

“…We note here that topological matter (Hasan and Kane, 2010;Qi and Zhang, 2011), specifically topological superconductors and Josephson junctions, have been proposed as potential novel elements in quantum thermodynamics and heat transport experiments due to their unconventional physical properties, see the recent work of Rivas and Martin-Delgado (2017), Bauer and Sothmann (2019), Scharf et al (2020), andPan, Sau, andDas Sarma (2021). Owing to the focus of the current paper, mainly on experiments, we do not discuss this topic further.…”

Colloquium: Quantum heat transport in condensed matter systems

“…We want to briefly note here that topological mat-ter (Hasan and Kane, 2010;Qi and Zhang, 2011), specifically topological superconductors and Josephson junctions, have been proposed as potential novel elements in quantum thermodynamics and heat transport experiments due to their unconventional physical properties, see e.g., non exhaustive list of some recent work in (Bauer and Sothmann, 2019;Pan et al, 2021;Rivas and Martin-Delgado, 2017;Scharf et al, 2020). Due to the focus of the current paper, mainly on experiments, we do not discuss this topic further.…”

Josephson quantum spin thermodynamics

“…Josephson-Stirling cycle [25,26] represented in Fig. 2, involves two isothermal and two isophasic processes.…”

“…In this context thermodynamic [21][22][23][24] properties of a Josephson Stirling engine have been discussed in Ref. 25, wherein a quantum spin Hall insulator based Josephson junction is shown to act as a quantum heat engine. Josephson Stirling engines aren't the only game in town, diffusive SNS junctions have been shown to operate as a Josephson-Otto or as Josephson-Stirling engines in Ref.…”