Entanglement of a bipartite multiparticle mesoscopic superposition
- Max-Planck Institut fuer Quantenoptik, Hans-Kopfermannstrasse 1, D-85748 Garching (Germany)
Entanglement of an open bipartite system is investigated. In particular, we calculate the entanglement of a subsystem A with k particles in an N atoms of two-level system (k{<=}N/2) initially prepared in a mesoscopic superposition {psi}>=[{phi}{sub 1}({theta}{sub 0})>{sup xN}+0>{sup xN}], with {phi}{sub 1}({theta}{sub 0})>=cos {theta}{sub 0}-0>+sin {theta}{sub 0}-1>, subject to the time evolution described by a dephasing channel. For an arbitrary number of particles N, numerical results are given for the full time evolution up to ten particles and 1{<=}k{<=}5. Analytical results are obtained for short times and asymptotic time regimes. Entanglement is maximum when {theta}{sub 0}={pi}/2 [Greenberger-Horne-Zeilinger (GHZ) state], independently of the number of particles in each partition. As N gets larger, entanglement tends to 1/2, and becomes independent of {theta}{sub 0}. The 'thermodynamic' regime (N{yields}{infinity} with fN finite, where f=k/N) is reached already for N=1000 particles. In the regime of k<<N and N{yields}{infinity}, the entanglement has its maximum value at {theta}{sub 0}={pi}/2 and for {theta}{sub 0}=0,{pi} its minimum value. The time evolution reduces the maximum value of entanglement, showing that the subsystem A loses coherence to the environment. Finally, we point out the differences between the entanglement rate obtained here from that one in Phys. Rev. Lett. 89, 210402 (2002), where only one N-particle subsystem is used.
- OSTI ID:
- 20718477
- Journal Information:
- Physical Review. A, Vol. 72, Issue 3; Other Information: DOI: 10.1103/PhysRevA.72.032104; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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