Additivity of decoherence measures for multiqubit quantum systems

Abstract

We introduce new measures of decoherence appropriate for evaluation of quantum computing designs. Environment-induced deviation of a quantum system's evolution from controlled dynamics is quantified by a single numerical measure. This measure is defined as a maximal norm of the density matrix deviation. We establish 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. This property is illustrated by exact calculations for a spin-boson model.

4 pages, 1 figure

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• Exact solution of the Hu-Paz-Zhang master equation
• Decoherence and gate performance of coupled solid state qubits
• Quantum measurement and decoherence
• Measures of Decoherence
• Effect of an External Field on Decoherence
• Onset of Decoherence in Open Quantum Systems

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• Collective Decoherence of Nuclear Spin Clusters
• Decoherence dynamics of a qubit coupled to a quantum two-level system
• Decoherence and relaxation of a qubit coupled to an Ohmic bath directly and via an intermediate harmonic oscillator
• 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
• One, Two, and $n$ Qubit Decoherence
• Protecting quantum systems from decoherence with unitary operations