Spin squeezing as a measure of entanglement in a two qubit system

Abstract

We show that two definitions of spin squeezing extensively used in the literature [M. Kitagawa and M. Ueda, Phys. Rev. A {\bf 47}, 5138 (1993) and D.J. Wineland {\it et al.}, Phys. Rev. A {\bf 50}, 67 (1994)] give different predictions of entanglement in the two-atom Dicke system. We analyze differences between the definitions and show that the Kitagawa and Ueda's spin squeezing parameter is a better measure of entanglement than the commonly used spectroscopic spin squeezing parameter. We illustrate this relation by examining different examples of a driven two-atom Dicke system in which spin squeezing and entanglement arise dynamically. We give an explanation of the source of the difference in the prediction of entanglement using the negativity criterion for entanglement. For the examples discussed, we find that the Kitagawa and Ueda's spin squeezing parameter is the sufficient and necessary condition for entanglement.

5 pages, 4 figures

References in corpus (3)

• Entangled states and collective nonclassical effects in two-atom systems
• Spin squeezing and pairwise entanglement for symmetric multiqubit states
• Entanglement and spin squeezing in the two-atom Dicke model

Cited by in corpus (13)

• Entanglement detection
• Quantum spin squeezing
• Coherent and Collective Quantum Optical Effects in Mesoscopic Systems
• Spin squeezing and entanglement
• First-order super-radiant phase transitions in a multi-qubit--cavity system
• Spin squeezing and maximal-squeezing time
• Single-atom entropy squeezing for two two-level atoms interacting with a single-mode radiation field
• Spin Squeezing, Negative Correlations, and Concurrence in the Quantum Kicked Top Model
• Concurrent spin squeezing and light squeezing in an atomic ensemble
• Spin squeezing and concurrence
• Spin squeezing and concurrence under Lee-Yang dephasing channels
• Establishment of correlated states in a quantum dot interacting with an acoustic phonon reservoir
• Entanglement and spin squeezing properties for three bosons in two modes