Quantum chaos challenges many-body localization

Šuntajs, Jan (avtor), Bonča, Janez (avtor), Prosen, Tomaž (avtor), Vidmar, Lev (avtor)

Characterizing states of matter through the lens of their ergodic properties is a fascinating new direction of research. In the quantum realm, the many-body localization (MBL) was proposed to be the paradigmatic ergodicity breaking phenomenon, which extends the concept of Anderson localization to interacting systems. At the same time, random matrix theory has established a powerful framework for characterizing the onset of quantum chaos and ergodicity (or the absence thereof) in quantum many-body systems. Here we numerically study the spectral statistics of disordered interacting spin chains, which represent prototype models expected to exhibit MBL. We study the ergodicity indicator $g=\mathrm{log}_{10}(t_H/t_{Th})$, which is defined through the ratio of two characteristic many-body time scales, the Thouless time $t_{Th}$ and the Heisenberg time $t_H$, and hence resembles the logarithm of the dimensionless conductance introduced in the context of Anderson localization. We argue that the ergodicity breaking transition in interacting spin chains occurs when both time scales are of the same order, $t_{Th} \approx t_H$, and g becomes a system-size independent constant. Hence, the ergodicity breaking transition in many-body systems carries certain analogies with the Anderson localization transition. Intriguingly, using a Berezinskii-Kosterlitz-Thouless correlation length we observe a scaling solution of g across the transition, which allows for detection of the crossing point in finite systems. We discuss the observation that scaled results in finite systems by increasing the system size exhibit a flow towards the quantum chaotic regime.

• Jezik: Angleški jezik
• Ključne besede: quantum statistical mechanics, quantum chaos
• Tipologija: 1.01 - Izvirni znanstveni članek
• Organizacija: FMF - Fakulteta za matematiko in fiziko
• Status publikacije: Objavljeno
• Različica publikacije: Recenzirani rokopis
• Leto izida: 2020
• Št. strani: Str. 062144-1-062144-12
• Številčenje: Vol. 102, iss. 6
• PID: 20.500.12556/RUL-124262
• UDK: 536.93
• ISSN pri članku: 2470-0045
• DOI: 10.1103/PhysRevE.102.062144
• COBISS.SI-ID: 46785795
• Datum objave v RUL: 13.01.2021

Gradivo je del revije

• Naslov: Physical review
• Skrajšan naslov: Phys. rev., E
• Založnik: American Physical Society
• ISSN: 2470-0045
• COBISS.SI-ID: 2048366611

Sekundarni jezik

• Jezik: Slovenski jezik
• Ključne besede: kvantna statistična mehanika, kvantni kaos