Single-particle entanglement

Can, M. Ali; Klyachko, Alexander A.; Shumovsky, A.S.

doi:10.1088/1464-4266/7/2/l01

Cited by 33 publications

(56 citation statements)

References 35 publications

(44 reference statements)

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“…The above discussion shows the utility of expectation values and statistical moments of observables in understanding quantum chaos. Uncertainty-based entanglement measures have been suggested outside the GE framework [34] providing links to important quantities such as the Wigner-Yanasi skew information [30,35] and a quantum analog of the Fisher information [36]. A dedicated study connectng GE to such measures will be presented elsewhere.…”

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confidence: 99%

Generalized entanglement as a natural framework for exploring quantum chaos

Weinstein

Viola

2006

Europhys. Lett.

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PACS. 03.67.Mn -Entanglement production, characterization, and manipulation. PACS. 03.65.Ud -Entanglement and quantum non-locality. PACS. 05.45.Mt -Quantum chaos; semiclassical methods.Abstract. -We demonstrate that generalized entanglement [Barnum et al., Phys. Rev. A 68, 032308 (2003)] provides a natural and reliable indicator of quantum chaotic behavior. Since generalized entanglement depends directly on a choice of preferred observables, exploring how generalized entanglement increases under dynamical evolution is possible without invoking an auxiliary coupled system or decomposing the system into arbitrary subsystems. We find that, in the chaotic regime, the long-time saturation value of generalized entanglement agrees with random matrix theory predictions. For our system, we provide physical intuition into generalized entanglement within a single system by invoking the notion of extent of a state. The latter, in turn, is related to other signatures of quantum chaos.Central to the study of quantum chaos [1] and broadly significant to fundamental quantum theory [2], is the determination of distinctive signatures that unambiguously identify quantum systems whose classical limit exhibits chaotic, versus regular, dynamics. Such signatures are discovered by contrasting quantized versions of classically chaotic and non-chaotic systems. A well-established static signature of quantum chaos is the accurate description of a chaotic operators' eigenvalue and eigenvector element statistics by random matrix theory (RMT) [1,3]. A dynamic indicator of quantum chaos is the fidelity decay behavior [4][5][6][7][8][9][10]. While both approaches have led to deep insights into quantum chaos and its relation to the underlying classical dynamics, they suffer from intrinsic weaknesses. Eigenvector statistics, for example, is basis-dependent. The effectiveness of fidelity decay as an indicator of quantum chaos is strongly influenced by the form of the perturbation. Indeed, regular systems may show chaotic fidelity decay behavior depending on the type of perturbation [8].A signature of quantum chaos which need not be subject to the above weaknesses and is very natural from a quantum information standpoint is entanglement generation. Chaotic evolution tends to produce states whose statistical properties are similar to those of random pure states. Because such states tend to be highly entangled [11], we expect that quantum

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confidence: 99%

Generalized entanglement as a natural framework for exploring quantum chaos

Weinstein

Viola

2006

Europhys. Lett.

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“…As a matter of fact, violation of Bell-type conditions indicates the absence of hidden classical variables in quantum mechanics rather than entanglement. This allows us to conclude that nonlocality and violation of classical realism alone are not the essential sign of entanglement and that there is no physical prohibition for the existence of entanglement of local objects (particles) caused by quantum correlations of their intrinsic degrees of freedom [4], [5], [6], [7], [8].…”

Section: Introductionmentioning

confidence: 95%

“…This notion does not contain any quantification of distance between separated entangled parts of a quantum system. Thus, it seems to be natural to assume that quantum system with strongly correlated intrinsic parts may manifest entanglement independent of distance between the parts and hence even as a local object without spatial separation of parts [4], [5], [6], [7], [8].…”

Section: Introductionmentioning

confidence: 99%

Single Qutrit Entanglement

Binicioğlu

Klyachko

Shumovsky

2007

Conference on Coherence and Quantum Optics

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“…Also, it was found that the spin squeezing is closely related to quantum entanglement [17][18][19][20][21][22], which plays an important role in quantum information and quantum computation. For an ensemble of two-level system, spin squeezing implies entanglement.…”

Section: Introductionmentioning

confidence: 99%

“…For an ensemble of two-level system, spin squeezing implies entanglement. At the same time, it was shown that a single spin-like system with S greater than 1/2 can also manifest entanglement [19][20][21], moreover, the single- * …”

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confidence: 99%

Mean spin direction and spin squeezing in superpositions of spin coherent states

et al. 2007

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Abstract:We consider the mean spin direction (MSD) of superpositions of two spin coherent states (SCS) | ± μ , and superpositions of |μ and |μ * with a relative phase. We find that the azimuthal angle exhibits a π transition for both states when we vary the relative phase. The spin squeezing of the states, and the bosonic counterpart of the mean spin direction are also discussed. c Versita Warsaw and Springer-Verlag Berlin Heidelberg. All rights reserved.Keywords: spin squeezing, mean spin direction PACS (2006): 03.65.Ud, 42.50.Dv Some investigations have partially focused on squeezing in spin systems [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] in recent years due to its practical applications e.g., in the fields of high-precision atomic clocks [4] and interferometers [3]. Also, it was found that the spin squeezing is closely related to quantum entanglement [17][18][19][20][21][22], which plays an important role in quantum information and quantum computation. For an ensemble of two-level system, spin squeezing implies entanglement. At the same time, it was shown that a single spin-like system with S greater than 1/2 can also manifest entanglement [19][20][21], moreover, the single- *

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Single-particle entanglement

Abstract: Using the approach to quantum entanglement based on the quantum fluctuations of observables, we show the existence of perfect entangled states of a single "spin-1" particle. We give physical examples related to the photons, condensed matter physics, and particle physics.

Cited by 33 publications

References 35 publications

Generalized entanglement as a natural framework for exploring quantum chaos

Generalized entanglement as a natural framework for exploring quantum chaos

Single Qutrit Entanglement

Mean spin direction and spin squeezing in superpositions of spin coherent states

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