Quantum distillation and confinement of vacancies in a doublon sea

Xia, Lin; Zundel, Laura A.; Carrasquilla, Juan; Reinhard, Aaron; Wilson, Joshua M.; Rigol, Marcos; Weiss, David S.

doi:10.1038/nphys3244

Cited by 46 publications

(64 citation statements)

References 32 publications

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“…Furthermore, the domain-wall melting describes the transient dynamics [34][35][36] of sudden-expansion experiments of interacting quantum gases in optical lattices (i.e., the release of initially trapped particles into an empty homogeneous lattice) [36][37][38][39]. Theoretically, the sudden expansion of interacting bosons in the presence of disorder was stud- ied in, e.g., [40,41] for the expansion from the correlated ground state in the trap, while for MBL, higher energy densities are relevant.…”

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confidence: 99%

Domain-wall melting as a probe of many-body localization

2016

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Motivated by a recent optical-lattice experiment by Choi et al. [Science 352, 1547[Science 352, (2016], we discuss how domain-wall melting can be used to investigate many-body localization. First, by considering noninteracting fermion models, we demonstrate that experimentally accessible measures are sensitive to localization and can thus be used to detect the delocalization-localization transition, including divergences of characteristic length scales. Second, using extensive time-dependent density matrix renormalization group simulations, we study fermions with repulsive interactions on a chain and a two-leg ladder. The extracted critical disorder strengths agree well with the ones found in existing literature.Introduction. In pioneering works based on perturbation theory [1,2], it was shown that Anderson localization, i.e., perfectly insulating behavior even at finite temperatures, can persist in the presence of interactions. Subsequent theoretical studies on mostly onedimensional (1D) model systems have unveiled many fascinating properties of such a many-body localized (MBL) phase. The MBL phase is a dynamical phase of matter defined in terms of the properties of highly excited manybody eigenstates. It is characterized by an area-law entanglement scaling in all eigenstates [3][4][5], a logarithmic increase of entanglement in global quantum quenches [6][7][8], failure of the eigenstate thermalization hypothesis [9] and therefore, memory of initial conditions [10,11]. The phenomenology of MBL systems is connected to the existence of a complete set of commuting (quasi) local integrals of motion (so-called "l-bits") that are believed to exist in systems in which all many-body eigenstates are localized [8,12,13]. These l-bits can be thought of as quasiparticles with an infinite lifetime, in close analogy to a zero-temperature Fermi liquid [1,14]. Important open questions pertain to the nature of the MBL transition and the existence of an MBL phase in higher dimensions, for which there are only few results (see, e.g., [15,16]), mainly due to the fact that numerical simulations are extremely challenging in dimensions higher than one for the MBL problem.The phenomenology of the MBL phase has mostly been established for closed quantum systems. A sufficiently strong coupling of a disordered, interacting system to a bath is expected to lead to thermalization (see, e.g., [17,18]). Thus, the most promising candidate systems for the experimental investigation of MBL physics are quantum simulators such as ultracold quantum gases in optical lattices or ion traps. So far, the cleanest evidence for MBL in an experiment has been reported for an interacting Fermi gas in an optical lattice with quasiperiodicity, realizing the Aubry-André model [19,20]. Other quantum gas experiments used the same quasi-periodic lattices or laser speckles to investigate Anderson localization [21,22] and the effect of interactions [23], however,

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confidence: 99%

Domain-wall melting as a probe of many-body localization

2016

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“…The quantum distillation effect was experimentally observed using bosons in a one-dimensional lattice [37] and the separation of the expanding cloud into regions with predominantly singlons or doublons (and local objects formed of more than two bosons) was beautifully demonstrated. This experiment operated in the weak-quantum distillation regime with no discernible increase beyond the initial density.…”

Section: Introductionmentioning

confidence: 99%

“…In parallel, experiments focusing on the nonequilibrium transport properties of atoms in optical lattices were pushed forward, ranging from the few-body [33][34][35] to the many-body regime [25,[36][37][38]. Not surprisingly, many unusual and sometimes counterintuitive phenomena exist in the transient dynamics of nonequilibrium problems, such as prethermalization [9,[39][40][41], the dynamical quasi-condensation of hard-core bosons [38,[42][43][44][45], or the quantum distillation mechanism [37,46,47].…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the experimental observation of quantum distillation with fermions and accessing the strong quantum distillation regime remain open. In a broader sense, the quantum distillation is one out of many interesting phenomena related to the presence of long-lived and heavy multi-particle objects in a sea of singlons, studied experimentally [37,64,75] and theoretically [65,[76][77][78][79][80][81].…”

Section: Introductionmentioning

confidence: 99%

“…Quantum distillation is the dynamical spatial separation of the lattice gas into one portion that carries predominantly interaction energy and another one that carries mostly kinetic energy. This spatial separation occurs during the so-called sudden expansion [25,[36][37][38], i.e., the release of an interacting quantum gas from a trap and its subsequent expansion into an empty optical lattice (see for theory work on this specific nonequilibrium problem). In the presence of strong on-site interactions U much larger than the typical tunneling matrix element t, particles of opposite spin bound into a doublon on the same site can only move with an effective tunneling matrix element t d ∼ 4t…”

Section: Introductionmentioning

confidence: 99%

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Efficiency of fermionic quantum distillation

et al. 2017

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We present a time-dependent density-matrix renormalization group investigation of the quantum distillation process within the Fermi-Hubbard model on a quasi-1D ladder geometry. The term distillation refers to the dynamical, spatial separation of singlons and doublons in the sudden expansion of interacting particles in an optical lattice, i.e., the release of a cloud of atoms from a trapping potential. Remarkably, quantum distillation can lead to a contraction of the doublon cloud, resulting in an increased density of the doublons in the core region compared to the initial state. As a main result, we show that this phenomenon is not limited to chains that were previously studied. Interestingly, there are additional dynamical processes on the two-leg ladder such as density oscillations and selftrapping of defects that lead to a less efficient distillation process. An investigation of the time evolution starting from product states provides an explanation for this behaviour. Initial product states are also considered, since in optical lattice experiments such states are often used as the initial setup. We propose configurations that lead to a fast and efficient quantum distillation.

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Spectral Structure and Doublon Dissociation in the Two‐Particle Non‐Hermitian Hubbard Model

Longhi

2023

Annalen der Physik

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Strongly‐correlated systems in non‐Hermitian models are an emergent area of research. Herein, a non‐Hermitian Hubbard model is considered, where the single‐particle hopping amplitudes on the lattice are not reciprocal, and provide exact analytical results of the spectral structure in the two‐particle sector of Hilbert space under different boundary conditions. The analysis unveils some interesting spectral and dynamical effects of purely non‐Hermitian nature and that deviate from the usual scenario found in the single‐particle regime. Specifically, a spectral phase transition of the Mott‐Hubbard band on the infinite lattice is predicted as the interaction energy is increased above a critical value, from an open to a closed loop in complex energy plane, and the dynamical dissociation of doublons, i.e., instability of two‐particle bound states, in the bulk of the lattice, with a sudden revival of the doublon state when the two particles reach the lattice edge. Particle dissociation observed in the bulk of the lattice is a clear manifestation of non‐Hermitian dynamics arising from the different lifetimes of single‐particle and two‐particle states, whereas the sudden revival of the doublon state at the boundaries is a striking burst edge dynamical effect peculiar to non‐Hermitian systems with boundary‐dependent energy spectra, here predicted for the first time for correlated particles.

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Quantum distillation and confinement of vacancies in a doublon sea

Cited by 46 publications

References 32 publications

Domain-wall melting as a probe of many-body localization

Domain-wall melting as a probe of many-body localization

Efficiency of fermionic quantum distillation

Spectral Structure and Doublon Dissociation in the Two‐Particle Non‐Hermitian Hubbard Model

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