Robust entanglement in antiferromagnetic Heisenberg chains by single-spin optimal control

Journal Article · Mon Mar 15 00:00:00 EDT 2010 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.81.032312· OSTI ID:21408391

Xiaoting, Wang; Schirmer, S G ^[1]; Bayat, Abolfazl; Bose, Sougato ^[2]

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1. Department of Applied Maths and Theoretical Physics, University of Cambridge, Wilberforce Rd., Cambridge CB3 0WA (United Kingdom)
2. Department of Physics and Astronomy, University College London, Gower St., London WC1E 6BT (United Kingdom)

We demonstrate how near-perfect entanglement (in fact arbitrarily close to maximal entanglement) can be generated between the end spins of an antiferromagnetic isotropic Heisenberg chain of length N, starting from the ground state in the N/2 excitation subspace, by applying a magnetic field along a given direction, acting on a single spin only. Temporally optimal magnetic fields to generate a singlet pair between the two end spins of the chain are calculated for chains up to length 20 using optimal control theory. The optimal fields are shown to remain effective in various nonideal situations including thermal fluctuations, magnetic field leakage, random system couplings, and decoherence. Furthermore, the quality of the entanglement generated can be substantially improved by taking these imperfections into account in the optimization. In particular, the optimal pulse of a given thermal initial state is also optimal for any other initial thermal state with lower temperature.

• OSTI ID: 21408391
• Journal Information: Physical Review. A, Vol. 81, Issue 3; Other Information: DOI: 10.1103/PhysRevA.81.032312; (c) 2010 The American Physical Society; ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
ANTIFERROMAGNETISM
EXCITATION
FLUCTUATIONS
GROUND STATES
LENGTH
MAGNETIC FIELDS
OPTIMAL CONTROL
PULSES
QUANTUM ENTANGLEMENT
RANDOMNESS
SPIN
ANGULAR MOMENTUM
CONTROL
DIMENSIONS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
MAGNETISM
PARTICLE PROPERTIES
VARIATIONS