Twisted boundary condition and thermal transport in quantum many-body systems

量子物理学・ナノサイエンス第415回セミナー

概要

Condensed matter systems are characterized by their response to various external fields. Although the electromagnetic response is of particular importance in electronic systems, there has been a growing interest in thermal transport of charge-neutral particles such as Majorana fermions [1]. Theoretically, there is a parallelism between electric and thermal responses. Linear transport coefficients are related by the Wiedemann-Franz law and an analogy holds between their driving forces [2]. In this talk, I will discuss another parallelism between electric and thermal transport [3]. We introduced a boundary condition twisted by time translation. This boundary condition is closely related to the thermal version of the Drude weight and Meissner stiffness just as the U(1) twisted boundary condition is related to the electric Drude weight via Kohn's formula [4]. In addition, I will show the equivalence between our boundary condition and the boost deformation, which is a kind of integrable deformations [5]. If time allows, I will show our recent study on the characterization of discrete time crystals in terms of a similar twisted boundary condition [6].

　　　　 　　　　
• [1] M. Banerjee et al., Nature 559, 205 (2018), Y. Kasahara et al., Nature 559, 227 (2018).
• [2] J. M. Luttinger, Phys. Rev. 135, A1505 (1964).
• [3] RN, T. Guo, S. Ryu, Phys. Rev. B 106, 155128 (2022).
• [4] W. Kohn, Phys. Rev. 133, A171 (1964)., J. T. Edwards and D. J. Thouless, J. Phys. C: Solid State Phys. 5, 807 (1972)., D. J. Thouless, Phys. Rev. Lett. 39, 1167 (1977).
• [5] T. Bargheer, N. Beisert, and F. Loebbert, J. Phys. A: Math. Theor.42, 285205 (2009).
• [6] RN, T. Guo, S. Ryu, arXiv:2504.21461.
　　　　

• 量子物理学・ナノサイエンス第415回セミナー

• 東京科学大学理学院・物理学系 ナノサイエンスを拓く量子物理学拠点　共催