Evaluation of Decoherence for Quantum Control and Computing

Abstract

Different approaches in quantifying environmentally-induced decoherence are considered. We identify a measure of decoherence, derived from the density matrix of the system of interest, that quantifies the environmentally induced error, i.e., deviation from the ideal isolated-system dynamics. This measure can be shown to have several useful features. Its behavior as a function of time has no dependence on the initial conditions, and is expected to be insensitive to the internal dynamical time scales of the system, thus only probing the decoherence-related time dependence. For a spin-boson model - a prototype of a qubit interacting with environment - we also demonstrate the property of additivity: in the regime of the onset of decoherence, the sum of the individual qubit error measures provides an estimate of the error for a several-qubit system, even if the qubits are entangled, as expected in quantum-computing applications. This makes it possible to estimate decoherence for several-qubits quantum computer gate designs for which explicit calculations are exceedingly difficult.

25 pages, 1 figure

Cited by in corpus (7)

• Non-Markov dynamics and phonon decoherence of a double quantum dot charge qubit
• Evaluation of Decoherence for Quantum Computing Architectures: Qubit System Subject to Time-Dependent Control
• Decoherence of Josephson charge qubit
• Initial Decoherence and Loss of Entanglement of Open Two-Qubit Systems
• Quantitative Treatment of Decoherence
• Study of the decoherence of a double quantum dot charge qubit via the Redfield equation
• Decoherence of Dynamically Manipulated Qubits