Experimental realization of multipartite entanglement via quantum Fisher information in a uniform antiferromagnetic quantum spin chain

George, Mathew; Silva, Saulo L. L.; Jain, Anil; Mohan, Arya; Adroja, D. T.; Sakai, Victoria García; Tomy, C. V.; Banerjee, A.; Rajendar, Goreti; N, Aswathi V.; Singh, R.; Jaiswal‐Nagar, D.

doi:10.1103/physrevresearch.2.043329

Cited by 46 publications

(28 citation statements)

References 58 publications

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“…4(b), above the quantum critical point g = 1 the optimal witness S X π + S Y 0 + S Z π ≥ 2 is violated for temperatures T /J 0.38. In contrast a criterion based on the quantum Fisher information (based on the dynamical structure factor for ZZ correlations [70], and which is considerably more challenging to estimate, both in theory and in experiments [71,72]) is violated for T /J 0.11; and a witness based on the same data as used in the present work [35], and optimized for T /J = 0.28, is violated for T /J 0.31. The entanglememt witness of Eq.…”

Section: Bipartite Witnessesmentioning

confidence: 70%

Unveiling quantum entanglement in many-body systems from partial information

Frérot,

Baccari,

Acín

2021

Preprint

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Quantum entanglement is commonly assumed to be a central resource for quantum computing and quantum simulation. Nonetheless, the capability to detect it in many-body systems is severely limited by the absence of sufficiently scalable and flexible certification tools. This issue is particularly critical in situations where the structure of entanglement is a priori unknown, and where one cannot rely on existing entanglement witnesses. Here, we implement a scheme in which the knowledge of the mean value of arbitrary observables can be used to probe multipartite entanglement in a scalable, certified and systematic manner. Specifically, we rely on positive semidefinite conditions, independent of partial-transposition-based criteria, necessarily obeyed if the data can be reproduced by a separable state. The violation of any of these conditions yields a specific entanglement witness, tailored to the data of interest, revealing the salient features of the data which are impossible to reproduce without entanglement. We validate this approach by probing theoretical many-body states of several hundreds of qubits relevant to existing experiments: a single-particle quench in a one-dimensional XX chain; a many-body quench in a two-dimensional XX model with 1/r 3 interactions; and thermal equilibrium states of Heisenberg and transverse-field Ising chains. In all cases, these investigations have lead us to discover new entanglement witnesses, some of which could be characterized analytically, generalizing existing results in the literature. In summary, our paper introduces a flexible data-driven entanglement detection technique for uncharacterized quantum many-body states, of immediate relevance to experiments in a quantum advantage regime.

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Section: Bipartite Witnessesmentioning

confidence: 70%

Unveiling quantum entanglement in many-body systems from partial information

Frérot,

Baccari,

Acín

2021

Preprint

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“…for arbitrary α, where ξ β = O(β) is explicitly given in Eq. (62). The above inequality also yields the general limits on the WYD skew information as well as the quantum Fisher information:…”

Section: (Schematic Diagram Of 1d Entanglement Clustering)mentioning

confidence: 84%

“…ρ β (K) and F ρ β (K) are the WYD skew information (58) and the quantum Fisher information (65), respectively. These general limits provide useful information for applying the quantum many-body systems to quantum metrology [60][61][62][63][64].…”

Section: (Schematic Diagram Of 1d Entanglement Clustering)mentioning

confidence: 99%

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Exponential clustering of bipartite quantum entanglement at arbitrary temperatures

Kuwahara,

Saito

2021

Preprint

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Macroscopic quantum effects play central roles in the appearance of inexplicable phenomena in low-temperature quantum many-body physics. Such macroscopic quantumness is often evaluated using long-range entanglement, i.e., entanglement in the macroscopic length scale. The long-range entanglement not only characterizes the novel quantum phases but also serves as a critical resource for quantum computation. Thus, the problem that arises is under which conditions can the longrange entanglement be stable even at room temperatures. Here, we show that bi-partite longrange entanglement is unstable at arbitrary temperatures and exponentially decays with distance. Our results are consistent with the existing observations that long-range entanglement at non-zero temperatures can exist in topologically ordered phases, where tripartite correlations are dominant. In the derivation of our result, we introduce a quantum correlation defined by the convex roof of the standard correlation function. We establish an exponential clustering theorem for generic quantum many-body systems for such a quantum correlation at arbitrary temperatures, which yields our main result by relating quantum correlation to quantum entanglement. As a simple application of our analytical techniques, we derived a general limit on the Wigner-Yanase-Dyson skew information and the quantum Fisher information, which will attract significant attention in the field of quantum metrology. Our work reveals novel general aspects of low-temperature quantum physics and sheds light on the characterization of long-range entanglement.

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“…By utilizing multiple witnesses, this approach goes beyond previous neutron scattering measurements of concurrence as applied to dimerized alternating chains [22,43] and molecular magnet systems [44]. By obtaining the scattering intensity in absolute units we also go beyond a recent study [45] of temperature scaling of QFI in an isotropic spin chain, allowing for a quantitative determination of the entanglement present. Our method may further be combined with independent measurements of EWs based on e.g.…”

Section: Introductionmentioning

confidence: 99%

Witnessing entanglement in quantum magnets using neutron scattering

Scheie,

Laurell,

Samarakoon

et al. 2021

Preprint

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We demonstrate how quantum entanglement can be directly witnessed in the quasi-1D Heisenberg antiferromagnet KCuF 3 . We apply three entanglement witnesses -one-tangle, two-tangle, and quantum Fisher information -to its inelastic neutron spectrum, and compare with spectra simulated by finite-temperature density matrix renormalization group (DMRG) and classical Monte Carlo methods. We find that each witness provides direct access to entanglement. Of these, quantum Fisher information is the most robust experimentally, and indicates the presence of at least bipartite entanglement up to at least 50 K, corresponding to around 10% of the spinon zone-boundary energy. We apply quantum Fisher information to higher spin-S Heisenberg chains, and show theoretically that the witnessable entanglement gets suppressed to lower temperatures as the quantum number increases. Finally, we outline how these results can be applied to higher dimensional quantum materials to witness and quantify entanglement.

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Experimental realization of multipartite entanglement via quantum Fisher information in a uniform antiferromagnetic quantum spin chain

Cited by 46 publications

References 58 publications

Unveiling quantum entanglement in many-body systems from partial information

Unveiling quantum entanglement in many-body systems from partial information

Exponential clustering of bipartite quantum entanglement at arbitrary temperatures

Witnessing entanglement in quantum magnets using neutron scattering

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