Quantum fragmentation in the extended quantum breakdown model

Journal Article · 03 October 2024 · Physical Review. B

DOI: https://doi.org/10.1103/physrevb.110.165109 · OSTI ID:2460503

Chen, Bo-Ting ^[1]; Prem, Abhinav ^[2]; Regnault, Nicolas ^[3]; Lian, Biao ^[4]

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1. Princeton University, NJ (United States); Institute for Advanced Study
2. Institute for Advanced Study, Princeton, NJ (United States)
3. Université Paris-Diderot (France); Princeton University, NJ (United States)
4. Princeton University, NJ (United States)

We introduce a one-dimensional (1D) extended quantum breakdown model comprising a fermionic and a spin degree of freedom per site, and featuring a spatially asymmetric breakdown-type interaction between the fermions and spins. Furthermore, our model resembles the breakdown process of particles incident into a cloud chamber with nonzero quantum amplitudes of both exciting and not exciting the local vapor atoms. We analytically show that, in the absence of any magnetic field for the spins, the model exhibits Hilbert space fragmentation within each symmetry sector into exponentially many Krylov subspaces and hence displays nonthermal dynamics. Here, we demonstrate that the fragmentation naturally occurs in an entangled basis and thus provides an example of “quantum fragmentation.” Besides establishing the nature of fragmentation analytically, we also study the long-time behavior of the entanglement entropy and its deviation from the expected Page value as a probe of ergodicity in the system. Upon introducing a magnetic field for the spins, most of the Krylov subspaces merge and the model becomes chaotic. Finally, we study the effects of strong randomness on the system and observe behavior similar to that of many-body localized systems.

• Research Organization: Institute for Advanced Study, Princeton, NJ (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: SC0009988
• OSTI ID: 2460503
• Journal Information: Physical Review. B, Journal Name: Physical Review. B Journal Issue: 16 Vol. 110; ISSN 2469-9950
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English