Many-body localized (MBL) phases of disordered quantum many-particle systems have a number of unique properties, including failure to act as a thermal bath and protection of quantum coherence. Studying MBL is complicated by the effects of rare ergodic regions, necessitating large system sizes and averaging over many disorder configurations. Here, building on the Feynman-Vernon theory of quantum baths, we characterize the quantum noise that a disordered spin system exerts on its parts via an influence matrix (IM). In this approach, disorder averaging is implemented exactly, and the thermodynamic-limit IM obeys a self-consistency equation. Viewed as a wavefunction in the space of trajectories of an individual spin, the IM exhibits slow scaling of temporal entanglement in the MBL phase. This enables efficient matrix product states computations to obtain temporal correlations, providing a benchmark for quantum simulations of non-equilibrium matter. The IM quantum noise formulation provides an alternative starting point for novel rigorous studies of MBL.
Motivated by experimental observation of the non-magnetic phase in the compounds with frustration and disorder, we study the ground state of the spin-$1/2$ square-lattice Heisenberg model with randomly distributed nearest-neighbor $J_1$ and next-nearest-neighbor $J_2$ couplings. By using the density matrix renormalization group (DMRG) calculation on cylinder system with circumference up to $10$ lattice sites, we identify a disordered phase between the Néel and stripe magnetic phase with growing $J_2 / J_1$ in the presence of strong bond randomness. The vanished spin-freezing parameter indicate…
We study the disorder-perturbed transport of two entangled particles in the absence of backscattering. This situation is, for instance, realized along edges of topological insulators. We find profoundly different responses to disorder-induced dephasing for the center-of-mass and relative coordinates: While a mirror symmetry protects even highly delocalized relative states when resonant with the symmetry condition, delocalizations in the center of mass (e.g. two-particle N00N states) remain fully sensitive to disorder. We demonstrate the relevance of these differences to the example of interfer…
Gravitational-wave lensing beyond rays: a disordered-system approach
INFN, Sezione di Padova（意大利国家核物理研究所帕多瓦分部）；Gran Sasso Science Institute（格兰萨索科学研究所）；INFN-Laboratori Nazionali del Gran Sasso（意大利国家核物理研究所格兰萨索国家实验室）；University of Pennsylvania（宾夕法尼亚大学）；SISSA, International School for Advanced Studies（国际高等研究院）；INFN, Sezione di Trieste（意大利国家核物理研究所里雅斯特分部）；IFPU, Istitute for Fundamental Physics of the Universe（宇宙基础物理研究所）；INAF-Osservatorio Astronomico di Padova（意大利国家天体物理研究所帕多瓦天文台）
Many theoretical studies of the voter model (or variations thereupon) involve order parameters that are population-averaged. While enlightening, such quantities may obscure important statistical features that are only apparent on the level of the individual. In this work, we ask which factors contribute to a single voter maintaining a long-term statistical bias for one opinion over the other in the face of social influence. To this end, a modified version of the network voter model is proposed, which also incorporates quenched disorder in the interaction strengths between individuals and the p…
We study the effect of the competition between disorder and stress enhancement in fracture processes using the local load sharing fiber bundle model, a model that hovers on the border between analytical tractability and numerical accessibility. We implement a disorder distribution with one adjustable parameter. The model undergoes a localization transition as a function of this parameter. We identify an order parameter for this transition and find that the system is in the localized phase over a finite range of values of the parameter bounded by a transition to the non-localized phase on both …
The hyperuniformity concept provides a unified means to classify all perfect crystals, perfect quasicrystals, and exotic amorphous states of matter according to their capacity to suppress large-scale density fluctuations. While the classification of hyperuniform point configurations has received considerable attention, much less is known about the classification of hyperuniform heterogeneous two-phase media, which include composites, porous media, foams, cellular solids, colloidal suspensions and polymer blends. The purpose of this article is to begin such a program for certain two-dimensional…
The Brillouin zone of the clean Weyl semimetal contains points at which the density of states (DoS) vanishes. Previous work suggested that below a certain critical concentration of impurities this features is preserved including in the presence of disorder. This result got criticized for its neglect of rare disorder fluctuations which might bind quantum states and hence generate a finite DoS. We here show that in spite of their existence these states are so fragile that their contribution effectively vanishes when averaged over continuous disorder distributions. This means that the integrity o…
We report experimental measurement of critical disorder in weakly disordered, one-dimensional photonic crystals. We measure the configurationally-averaged transmission at various degrees of weak disorder. We extract the density of states (DoS) after fitting the transmission with theoretical profiles, and identify the Lifshitz tail realized by weak disorder. We observe the vanishing of Van Hove singularities and the flattening of the DoS with increasing disorder in our system. Systematic variation of disorder strength allows us to study the behavior of Lifshitz exponent with the degree of disor…
