Quantum many-body scars have been put forward as counterexamples to the Eigenstate Thermalization Hypothesis. These atypical states are observed in a range of correlated models as long-lived oscillations of local observables in quench experiments starting from selected initial states. The long-time memory is a manifestation of quantum non-ergodicity generally linked to a sub-extensive generation of entanglement entropy, the latter of which is widely used as a diagnostic for identifying quantum many-body scars numerically as low entanglement outliers. Here we show that, by adding kinetic constraints to a fractionalized orthogonal metal, we can construct a minimal model with orthogonal quantum many-body scars leading to persistent oscillations with infinite lifetime coexisting with rapid volume-law entanglement generation. Our example provides new insights into the link between quantum ergodicity and many-body entanglement while opening new avenues for exotic non-equilibrium dynamics in strongly correlated multi-component quantum systems.
We study the nature of the ergodicity-breaking "quantum many-body scar" states that appear in the PXP model describing constrained Rabi oscillations. For a {wide class of bipartite lattices} of Rydberg atoms, we reveal that the nearly energy-equidistant tower of these states arises from the Hamiltonian's close proximity to a generalized projector-embedding form, a structure common to many models hosting quantum many-body scars. We construct a non-Hermitian, but strictly local extension of the PXP model hosting exact quantum scars, and show how various Hermitian scar-stabilizing extensions from…
我们通常期望量子系统热化并满足本征态热化假设（ETH），该假设指出有限的能量密度本征态是热的。然而，一些系统，如多体局域系统和具有量子多体疤痕的系统，违反ETH并具有高能无热本征态。在有疤痕的系统中，大多数本征态热化，但少数非典型疤痕态不会。当特定的初始产物态随时间演化时，疤痕态可以引起周期性的复苏，这可以通过实验检测到。最近，发现了具有磁有序的3色本征态的自旋哈密顿算子族，这些本征态是量子多体伤疤[Lee et al. Phys. Rev. B 101，241111（2020）]。这些模型可以在任何可以用三角形平铺的晶格中实现，例如三角形或kagome晶格，并且已经被证明与海森堡kagome反铁磁体中的量子自旋液体物理学有密切联系。在这项工作中，我们介绍了一个广义家庭的$n$ -彩色哈密顿与“螺旋色”的本征态由$n$ -自旋图案，如多边形或多面体。我们展示了这些模型如何在许多不同的晶格几何形状中实现，并提供了数值证据，证明它们可以表现出量子多体疤痕，这些疤痕可以通过随时间演化的简单乘积态观察到。这些哈密顿量的简单结构使它们成为未来量子多体伤疤实验研究的有希望的候选者。
Ongoing development of quantum simulators allows for a progressively finer degree of control of quantum many-body systems. This motivates the development of efficient approaches to facilitate the control of such systems and enable the preparation of non-trivial quantum states. Here we formulate an approach to control quantum systems based on matrix product states~(MPS). We compare counter-diabatic and leakage minimization approaches to the so-called local steering problem, that consists in finding the best value of the control parameters for generating a unitary evolution of the specific MPS s…
Symmetry protected quantum many body scars through half-gauging
Okinawa Institute of Science and Technology Graduate University（冲绳科学技术大学院大学）；National Tsing Hua University（国立清华大学）；National Center for Theoretical Sciences（国家理论科学中心）；Academia Sinica（中央研究院）
Although entanglement is a key resource for quantum-enhanced metrology, not all entanglement is useful. For example in the process of many-body thermalisation, bipartite entanglement grows rapidly, naturally saturating to a volume law. This type of entanglement generation is ubiquitous in nature but has no known application in most quantum technologies. The generation, stabilisation and exploitation of genuine multipartite entanglement, on the other hand, is far more elusive yet highly desirable for metrological applications. Recently it has been shown that quantum many-body scars can have ext…
Systematic construction of quantum many-body scars in frustrated Rydberg arrays
Institute of Science and Technology Austria (ISTA)（奥地利科学与技术研究所）；Physics Department, Technical University of Munich, TUM School of Natural Sciences（慕尼黑工业大学自然科学学院物理系）；Munich Center for Quantum Science and Technology (MCQST)（慕尼黑量子科学与技术中心）
We construct a 1D model Hamiltonian of spinless fermions for which the spinless analogue of $η$-pairing states are quantum many-body scars of the model. These states are excited states and display subvolume entanglement entropy scaling; they form a tower of states that are equally spaced in energy (resulting in periodic oscillations in the Loschmidt echo and in the time evolution of observables for initial states prepared in a superposition of them) and are atypical in the sense that they weakly break the eigenstate thermalization hypothesis, while the other excited states are thermal. We exte…
Quantum many-body scars in random unitary circuits
Université Paris-Saclay（巴黎萨克雷大学）；CNRS（法国国家科学研究中心）；Laboratoire de Physique de l’École normale supérieure（巴黎高等师范学院物理实验室）；ENS（巴黎高等师范学院）；Université PSL（巴黎文理研究大学）；Sorbonne Université（索邦大学）；Université Paris Cité（巴黎西岱大学）
