Persistent entanglement in a class of eigenstates of quantum Heisenberg spin glasses

Kannawadi, Arun; Sharma, Auditya; Lakshminarayan, Arul

doi:10.1209/0295-5075/115/57005

Cited by 4 publications

(4 citation statements)

References 30 publications

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“…For pure states, entanglement entropy has established itself as the standard measure of quantum entanglement, and has been extensively used to study different many-body phases and make a distiction amongst them 15,16 . Intuitively, one would expect that the greater the delocalization, the more the entanglement and vice versa, although exceptions exist 29 . We start with a brief discussion of the calculation of the entanglement entropy of fermions in the ground state 28,[30][31][32] .…”

Section: A Entanglement Entropymentioning

confidence: 99%

Study of counterintuitive transport properties in the Aubry-André-Harper model via entanglement entropy and persistent current

Roy

Sharma

2019

Phys. Rev. B

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The single particle eigenstates of the Aubry-André-Harper model are known to show a delocalization-localization transition at a finite strength of the quasi-periodic disorder. In this work, we point out that an intimate relationship exists between the sub-band structure of the spectrum and transport properties of the model. To capture the transport properties we have not only used a variety of single-particle measures like inverse participation ratio, and von Neumann entropy, but also many-particle measures such as persistent current and its variance, and many body entanglement entropy. The many-particle measures are very sensitive to the sub-band structure of the spectrum. Even in the delocalized phase, surprisingly the entanglement entropy is substantially suppressed when the Fermi level is in the band gaps whereas the persistent current is vanishingly small for the same locations of the Fermi level. The entanglement entropy seems to follow area-law exclusively for these special locations of Fermi level or filling fractions of free fermions. A study of the standard deviation of persistent current offers further distinguishing features for the special fillings. In the delocalized phase, the standard deviation vs. mean persistent current curves are discontinuous for the non-special values of filling fractions and continuous (closed) for the special values of filling fractions whereas in the localized phase, these curves become straight lines for both types of filling fractions. Our results, specially on the persistent current, can potentially be tested experimentally using the present day set-ups based on ultra-cold atoms.

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Section: A Entanglement Entropymentioning

confidence: 99%

Study of counterintuitive transport properties in the Aubry-André-Harper model via entanglement entropy and persistent current

Roy

Sharma

2019

Phys. Rev. B

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“…The connection between localization and entanglement is subtle. Intuitively, one would expect that the greater the delocalization, the more the entanglement and vice versa; however, this correlation is not absolute and counterexamples are available 62 . We also discuss the relationship between subsystem number fluctuations and entanglement entropy in the model.…”

Section: B Fermionic Entanglement and Fluctuationsmentioning

confidence: 99%

Entanglement contour perspective for “strong area-law violation” in a disordered long-range hopping model

Roy

Sharma

2018

Phys. Rev. B

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We numerically investigate the link between the delocalization-localization transition and entanglement in a disordered long-range hopping model of spinless fermions by studying various static and dynamical quantities. This includes the inverse participation ratio, level-statistics, entanglement entropy and number fluctuations in the subsystem along with quench and wave-packet dynamics. Finite systems show delocalized, quasi-localized and localized phases. The delocalized phase shows strong area-law violation whereas the (quasi)localized phase adheres to (for large subsystems) the strict area law. The idea of 'entanglement contour' nicely explains the violation of area-law and its relationship with 'fluctuation contour' reveals a signature at the transition point. The relationship between entanglement entropy and number fluctuations in the subsystem also carries signatures for the transition in the model. Results from Aubry-Andre-Harper model are compared in this context. The propagation of charge and entanglement are contrasted by studying quench and wavepacket dynamics at the single-particle and many-particle levels.arXiv:1711.06338v2 [cond-mat.str-el]

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“…A procedure to extract the extent of entanglement in spin systems from the inverse participation ratio has been outlined in [12], and a measure of entanglement ξ ipr has been defined. Extensive examination of the efficacy of ξ ipr in interacting spin systems has been carried out (see, for instance, [13,14,15,16,17,18,19,20,21]). The limitations of ξ ipr in capturing the salient features of the SVNE in entangled qubit systems have been pointed out in [15].…”

Section: Introductionmentioning

confidence: 99%

Estimation of entanglement in bipartite systems directly from tomograms

Sharmila

Lakshmibala

Balakrishnan

2019

Quantum Inf Process

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We investigate the advantages of extracting the degree of entanglement in bipartite systems directly from tomograms, as it is the latter that are readily obtained from experiments. This would provide a superior alternative to the standard procedure of assessing the extent of entanglement between subsystems after employing the machinery of state reconstruction from the tomogram. The latter is both cumbersome and involves statistical methods, while a direct inference about entanglement from the tomogram circumvents these limitations. In an earlier paper, we had identified a procedure to obtain a bipartite entanglement indicator directly from tomograms. To assess the efficacy of this indicator, we now carry out a detailed investigation using two nonlinear bipartite models by comparing this tomographic indicator with standard markers of entanglement such as the subsystem linear entropy and the subsystem von Neumann entropy and also with a commonly-used indicator obtained from inverse participation ratios. The two model systems selected for this purpose are a multilevel atom interacting with a radiation field, and a double-well Bose-Einstein condensate. The role played by the specific initial states of these two systems in the performance of the tomographic indicator is also examined. Further, the efficiency of the tomographic entanglement indicator during the dynamical evolution of the system is assessed from a timeseries analysis of the difference between this indicator and the subsystem von Neumann entropy.

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Persistent entanglement in a class of eigenstates of quantum Heisenberg spin glasses

Cited by 4 publications

References 30 publications

Study of counterintuitive transport properties in the Aubry-André-Harper model via entanglement entropy and persistent current

Study of counterintuitive transport properties in the Aubry-André-Harper model via entanglement entropy and persistent current

Entanglement contour perspective for “strong area-law violation” in a disordered long-range hopping model

Estimation of entanglement in bipartite systems directly from tomograms

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