Quantum decoherence of two qubits

Journal Article · Thu Oct 15 04:00:00 EDT 2009 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.80.042108· OSTI ID:21316347

Helm, Julius; Strunz, Walter T ^[1]

---

1. Institut fuer Theoretische Physik, Technische Universitaet Dresden, 01062 Dresden (Germany)

It is commonly stated that decoherence in open quantum systems is due to growing entanglement with an environment. In practice, however, surprisingly often decoherence may equally well be described by random unitary dynamics without invoking a quantum environment at all. For a single qubit, for instance, pure decoherence (or phase damping) is always of random unitary type. Here, we construct a simple example of true quantum decoherence of two qubits: we present a feasible phase damping channel of which we show that it cannot be understood in terms of random unitary dynamics. We give a very intuitive geometrical measure for the positive distance of our channel to the convex set of random unitary channels and find remarkable agreement with the so-called Birkhoff defect based on the norm of complete boundedness.

• OSTI ID: 21316347
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 4 Vol. 80; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
DAMPING
DISTANCE
ENVIRONMENT
GEOMETRY
QUANTUM COMPUTERS
QUANTUM DECOHERENCE
QUANTUM ENTANGLEMENT
QUBITS
RANDOMNESS