Direct versus measurement-assisted bipartite entanglement in multiqubit systems and their dynamical generation in spin systems

Journal Article · Mon Aug 15 04:00:00 EDT 2005 · Physical Review. A

DOI:https://doi.org/10.1103/PhysRevA.72.022321· OSTI ID:20718080

Koniorczyk, Matyas; Rapcan, Peter; Buzek, Vladimir ^[1]

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1. Research Centre for Quantum Information, Institute of Physics, Slovak Academy of Sciences Dubravska cesta 9, 845 11 Bratislava (Slovakia)

We consider multiqubit systems and relate quantitatively the problems of generating cluster states with high values of concurrence of assistance, and of generating states with maximal bipartite entanglement. We prove an upper bound for the concurrence of assistance. We consider dynamics of spin-1/2 systems that model qubits, with different couplings and possible presence of magnetic field, to investigate the appearance of the discussed entanglement properties. We find that states with maximal bipartite entanglement can be generated by an isotropic XY Hamiltonian, and their generation can be controlled by the initial state of one of the spins. The same Hamiltonian is capable of creating states with high concurrence of assistance from a suitably chosen initial state. We show that the production of graph states using the Ising Hamiltonian is controllable via a single-qubit rotation of one spin-1/2 subsystem in the initial multiqubit state. We show that the property of Ising dynamics to convert a product-state basis into a special maximally entangled basis is temporally enhanced by the application of a suitable magnetic field. Similar basis transformations are found to be feasible in the case of isotropic XY couplings with a magnetic field.

• OSTI ID: 20718080
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 2 Vol. 72; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
74 ATOMIC AND MOLECULAR PHYSICS
COUPLING
HAMILTONIANS
ISING MODEL
MAGNETIC FIELDS
QUANTUM COMPUTERS
QUANTUM ENTANGLEMENT
QUANTUM MECHANICS
QUBITS
ROTATION
SPIN
TRANSFORMATIONS