Spin-gap spectroscopy in a bosonic flux ladder

Strinati, Marcello Calvanese; Gerbier, Fabrice; Mazza, Leonardo

doi:10.1088/1367-2630/aa9ca2

Cited by 12 publications

(5 citation statements)

References 80 publications

(113 reference statements)

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“…Several interesting properties have been highlighted by a number of works, for both bosonic [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] and fermionic [53][54][55][56][57][58][59][60][61] flux ladders. Importantly, it was shown that flux ladders, in the quasi-1D limit, can host states that share fundamental properties with 2D FQH states [62][63][64][65], and that can be directly tested in current cold-atom experiments as well as DMRG or MPS simulations [64,65].…”

Section: Introduction and Main Resultsmentioning

confidence: 99%

Pretopological fractional excitations in the two-leg flux ladder

Strinati,

Sahoo,

Shtengel

et al. 2019

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Topological order, the hallmark of fractional quantum Hall states, is primarily defined in terms of ground-state degeneracy on higher-genus manifolds, e.g. the torus. We investigate analytically and numerically the smooth crossover between this topological regime and the Tao-Thouless thin torus quasi-1D limit. Using the wire-construction approach, we analyze an emergent charge density wave (CDW) signifying the break-down of topological order, and relate its phase shifts to Wilson loop operators. The CDW amplitude decreases exponentially with the torus circumference once it exceeds the transverse correlation length controllable by the inter-wire coupling. By means of numerical simulations based on the matrix product states (MPS) formalism, we explore the extreme quasi-1D limit in a two-leg flux ladder and present a simple recipe for probing fractional charge excitations in the ν = 1/2 Laughlin-like state of hard-core bosons. We discuss the possibility of realizing this construction in cold-atom experiments. We also address the implications of our findings to the possibility of producing non-Abelian zero modes. As known from rigorous no-go theorems, topological protection for exotic zero modes such as parafermions cannot exist in 1D fermionic systems and the associated degeneracy cannot be robust. Our theory of the 1D-2D crossover allows to calculate the splitting of the degeneracy, which vanishes exponentially with the number of wires, similarly to the CDW amplitude.

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Section: Introduction and Main Resultsmentioning

confidence: 99%

Pretopological fractional excitations in the two-leg flux ladder

Strinati,

Sahoo,

Shtengel

et al. 2019

Preprint

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“…In the context of the ladder model, Eq. ( 1), other distribution functions that are related to n(k) have been considered [26,53,54], as follows.…”

Section: Leg-resolved Mdfsmentioning

confidence: 99%

Finite-temperature properties of interacting bosons on a two-leg flux ladder

2019

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Quasi-one-dimensional lattice systems such as flux ladders with artificial gauge fields host rich quantum-phase diagrams that have attracted great interest. However, so far, most of the work on these systems has concentrated on zero-temperature phases while the corresponding finitetemperature regime remains largely unexplored. The question if and up to which temperature characteristic features of the zero-temperature phases persist is relevant in experimental realizations. We investigate a two-leg ladder lattice in a uniform magnetic field and concentrate our study on chiral edge currents and momentum-distribution functions, which are key observables in ultracold quantum-gas experiments. These quantities are computed for hard-core bosons as well as noninteracting bosons and spinless fermions at zero and finite temperatures. We employ a matrixproduct-state based purification approach for the simulation of strongly interacting bosons at finite temperatures and analyze finite-size effects. Our main results concern the vortex-fluid-to-Meissner crossover of strongly interacting bosons. We demonstrate that signatures of the vortex-fluid phase can still be detected at elevated temperatures from characteristic finite-momentum maxima in the momentum-distribution functions, while the vortex-fluid phase leaves weaker fingerprints in the local rung currents and the chiral edge current. In order to determine the range of temperatures over which these signatures can be observed, we introduce a suitable measure for the contrast of these maxima. The results are condensed into a finite-temperature crossover diagram for hard-core bosons. * Corresponding author: heidrich-meisner@uni-goettingen.deFIG. 1. Meissner and vortex-fluid phase. Ground-state particle current patterns of noninteracting bosons for (a) Meissner phase and (b) vortex-fluid phase. Red arrows indicate the direction and, by their length, the strength of the local currents. The size of the dots and the background shading represent the local particle density. The Hamiltonian parameters φ, J ⊥ , J and U are introduced in Eq.(1). A comprehensive analysis of the Meissner and vortex-fluid phases can be found in, e.g., Refs. [26,[29][30][31][32].fraction of the latter work based on the density-matrix renormalization-group method [33,34], have provided extensive theoretical results regarding the ground-state properties of interacting quantum gases on such ladderlike systems [26,[29][30][31][32]. The presence of gauge fields clearly enriches the corresponding phase diagrams, which by now have been mapped out in large part. For instance, these phase diagrams host superfluid and Mottinsulating vortex-liquid and Meissner phases [29,30,32] and vortex lattices [29,44,46], as well as charge-densitywave [46,48] and biased-ladder phases [40]. Typi-arXiv:1901.07083v3 [cond-mat.quant-gas]

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“…Moreover, the possible existence of Laughlin-like states has attracted great interest [44][45][46][47][48][49] and the study of the Hall effect in flux ladders remains an active line of research [50][51][52][53]. At the same time, proposing adequate methods to probe these phases, i.e., via spectroscopic [54][55][56], transport [57][58][59][60], or microscopic probes, or via global measurements, remains an important question.…”

Section: Introductionmentioning

confidence: 99%

Interacting bosonic flux ladders with a synthetic dimension: Ground-state phases and quantum quench dynamics

et al. 2020

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Flux ladders constitute the minimal setup enabling a systematic understanding of the rich physics of interacting particles subjected simultaneously to strong magnetic fields and a lattice potential. In this work, the ground-state phase diagram of a flux-ladder model is mapped out using extensive density-matrix renormalization-group simulations. The emphasis is put on parameters which can be experimentally realized exploiting the internal states of potassium atoms as a synthetic dimension. The focus is on accessible observables such as the chiral current and the leg-population imbalance. Considering a particle filling of one boson per rung, we report the existence of a Mott-insulating Meissner phase as well as biased-ladder phases on top of superfluids and Mott insulators. Furthermore, we demonstrate that quantum quenches from suitably chosen initial states can be used to probe the equilibrium properties in the transient dynamics. Concretely, we consider the instantaneous turning on of hopping matrix elements along the rungs or legs in the synthetic flux-ladder model, with different initial particle distributions. We show that clear signatures of the biased-ladder phase can be observed in the transient dynamics. Moreover, the behavior of the chiral current in the transient dynamics is discussed. The results presented in this work provide guidelines for future implementations of flux ladders in experimental setups exploiting a synthetic dimension.

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Spin-gap spectroscopy in a bosonic flux ladder

Cited by 12 publications

References 80 publications

Pretopological fractional excitations in the two-leg flux ladder

Pretopological fractional excitations in the two-leg flux ladder

Finite-temperature properties of interacting bosons on a two-leg flux ladder

Interacting bosonic flux ladders with a synthetic dimension: Ground-state phases and quantum quench dynamics

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