Localization of extended quantum objects

Article

关键词: MANY-BODY LOCALIZATION;    STATISTICAL-MECHANICS;    PHASE-TRANSITIONS;    THERMALIZATION;    SYSTEM;    SUPERCONDUCTORS;    DISORDER;    CHAINS;   

DOI  :  10.1103/PhysRevB.98.134301

来源: SCIE

【 摘 要 】

A quantum system of particles can exist in a localized phase, exhibiting ergodicity breaking and maintaining forever a local memory of its initial conditions. We generalize this concept to a system of extended objects, such as strings and membranes, arguing that such a system can also exhibit localization in the presence of sufficiently strong disorder (randomness) in the Hamiltonian. We show that localization of large extended objects can be mapped to a lower-dimensional many-body localization problem. For example, motion of a string involves propagation of pointlike signals down its length to keep the different segments in causal contact. For sufficiently strong disorder, all such internal modes will exhibit many-body localization, resulting in the localization of the entire string. The eigenstates of the system can then be constructed perturbatively through a convergent string locator expansion. We propose a type of out-of-time-order string correlator as a diagnostic of such a string localized phase. Localization of other higher-dimensional objects, such as membranes, can also be studied through a hierarchical construction by mapping onto the localization of lower-dimensional objects. Our arguments are asymptotic (i.e., valid up to rare regions) but they extend the notion of localization (and localization protected order) to a host of settings where such ideas previously did not apply. These include high-dimensional ferromagnets with domain wall excitations, three-dimensional topological phases with looplike excitations, and three-dimensional type-II superconductors with flux line excitations. In type-II superconductors, localization of flux lines could stabilize superconductivity at energy densities where a normal state would arise in thermal equilibrium.

【 授权许可】

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