Speaker
Description
We provide perspectives on spatial deformation techniques that are useful for driving local states to the equilibrium that mimics the thermodynamic limit.
The first case we focus on is the construction of boundary operators that effectively represent semi-infinite environments connected to the main finite system[1}. With this setup, the entanglement entropy measured in the central subsystem follows the conformal field theory (CFT) predictions not only for translationally invariant one-dimensional models but also for systems with quenched randomness. Furthermore, quench dynamics performed in this setup enable the tracking of long-time evolution while largely avoiding quasiparticle reflections from the boundaries.
Another example is the sine-square deformation (SSD), in which the local energy scale of the Hamiltonian is continuously reduced toward the system edges. This spatial modulation efficiently renormalizes the energy spectrum by compressing states into the low-energy sector and thereby strongly suppressing finite-size effects. While our earlier study [2] mainly focused on ground-state properties, we also found that SSD can yield physically meaningful finite-temperature behavior[3].
We also briefly mention our recent findings on the strongly correlated systems, where placing the spatially modulated on-site potentials yields the site-dependent excitation spectrum, each realizing the bulk ones for the corresponding chemical potential levels [4].
[1] S. Shimozono and C. Hotta, PRB, doi: 10.1103/bbnt-brjz
[2] C. Hotta, N. Shibata, PRB 86, 041108 (2012); C. Hotta, S. Nishimoto, N. Shibata, PRB 87, 115128 (2013).
[3] C. Hotta, T. Nakamaniwa, T. Nakamura, PRE 104,034133 (2021)
[4] K Matsuki, C Hotta, K Asano, PRB 112, 045146.