Unification of dynamical decoupling and the quantum Zeno effect

Journal Article · Mon Mar 01 04:00:00 EST 2004 · Physical Review. A

DOI:https://doi.org/10.1103/PhysRevA.69.032314· OSTI ID:20640840

Facchi, P; Pascazio, S ^[1]; Lidar, D A ^[2]

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1. Dipartimento di Fisica, Universita di Bari I-70126 Bari (Italy)
2. Chemical Physics Theory Group, Chemistry Department, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6 (Canada)

We unify the quantum Zeno effect (QZE) and the 'bang-bang' (BB) decoupling method for suppressing decoherence in open quantum systems: in both cases strong coupling to an external system or apparatus induces a dynamical superselection rule that partitions the open system's Hilbert space into quantum Zeno subspaces. Our unification makes use of von Neumann' s ergodic theorem and avoids making any of the symmetry assumptions usually made in discussions of BB. Thus we are able to generalize the BB to arbitrary fast and strong pulse sequences, requiring no symmetry, and to show the existence of two alternatives to a pulsed BB: continuous decoupling and pulsed measurements. Our unified treatment enables us to derive limits on the efficacy of the BB method: we explicitly show that the inverse QZE implies that the BB can in some cases accelerate, rather than inhibit, decoherence.

• OSTI ID: 20640840
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 3 Vol. 69; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
CORRELATIONS
DECOUPLING
ENERGY LEVELS
HILBERT SPACE
PARTITION
PULSES
QUANTUM MECHANICS
SUPERSELECTION RULES
SYMMETRY