Creation of Two-Particle Entanglement in Open Macroscopic Quantum Systems

Journal Article · Sun Jan 01 00:00:00 EST 2012 · Advances in Mathematical Physics

DOI:https://doi.org/10.1155/2012/375182· OSTI ID:1198083

Merkli, M. ^[1]; Berman, G. P. ^[2]; Borgonovi, F. ^[3]; Tsifrinovich, V. I. ^[4]

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1. Department of Mathematics and Statistics, Memorial University of Newfoundland, St. John’s, NL, Canada A1C 5S7
2. Theoretical Division, Los Alamos National Laboratory, MS B213, Los Alamos, NM 87545, USA
3. Dipartimento di Matematica e Fisica, and Interdisciplinary Laboratories for Advanced Materials Physics, Università Cattolica, Via Musei 41, 25121 Brescia, Italy, Istituto Nazionale di Fisica Nucleare, Sezione di Pavia, Via Bassi 6, 27100 Pavia, Italy
4. Department of Applied Physics, Polytechnic Institute of NYU, 6 MetroTech Center, Brooklyn, NY 11201, USA

We consider an open quantum system of $N$ not directly interacting spins (qubits) in contact with both local and collective thermal environments. The qubit-environment interactions are energy conserving. We trace out the variables of the thermal environments and $N-2$ qubits to obtain the time-dependent reduced density matrix for two arbitrary qubits. We numerically simulate the reduced dynamics and the creation of entanglement (concurrence) as a function of the parameters of the thermal environments and the number of qubits, $N$ . Our results demonstrate that the two-qubit entanglement generally decreases as $N$ increases. We show analytically that, in the limit $N\to \infty$ , no entanglement can be created. This indicates that collective thermal environments cannot create two-qubit entanglement when many qubits are located within a region of the size of the environment coherence length. We discuss possible relevance of our consideration to recent quantum information devices and biosystems.

• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: DEAC52-06NA25396
• OSTI ID: 1198083
• Journal Information: Advances in Mathematical Physics, Journal Name: Advances in Mathematical Physics Vol. 2012; ISSN 1687-9120
• Publisher: Hindawi Publishing Corporation
• Country of Publication: Country unknown/Code not available
• Language: English