Decoherence in a N-qubit solid-state quantum computer

Abstract

We investigate the decoherence process for a quantum register composed of N qubits coupled to an environment. We consider an environment composed of one common phonon bath and several electronic baths. This environment is relevant to the implementation of a charge based solid-state quantum computer. We explicitly compute the time evolution of all off-diagonal terms of the register's reduced density matrix. We find that in realistic configurations, "superdecoherence" and "decoherence free subspaces" do not exist for an N-qubit system. This means that all off-diagonal terms decay like exp(-q(t)N), where q(t) is of the same order as the decay function of a single qubit.

11 pages

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• Universal quantum computation with symmetric qubit clusters coupled to an environment
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• Conditions for superdecoherence
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• 5-qubit quantum error correction in a charge qubit quantum computer
• A Chain-Boson Model for the Decoherence and Relaxation of a Few Coupled SQUIDs in a Phonon Bath