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arXiv · 1311.6321

Generation and stabilization of a three-qubit entangled W state in circuit QED via quantum feedback control

Shang-Yu Huang·Hsi-Sheng Goan·Xin-Qi Li·G. J. Milburn
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Abstract

Circuit cavity quantum electrodynamics (QED) is proving to be a powerful platform to implement quantum feedback control schemes due to the ability to control superconducting qubits and microwaves in a circuit. Here, we present a simple and promising quantum feedback control scheme for deterministic generation and stabilization of a three-qubit $W$ state in the superconducting circuit QED system. The control scheme is based on continuous joint Zeno measurements of multiple qubits in a dispersive regime, which enables us not only to infer the state of the qubits for further information processing but also to create and stabilize the target $W$ state through adaptive quantum feedback control. We simulate the dynamics of the proposed quantum feedback control scheme using the quantum trajectory approach with an effective stochastic maser equation obtained by a polaron-type transformation method and demonstrate that in the presence of moderate environmental decoherence, the average state fidelity higher than $0.9$ can be achieved and maintained for a considerable long time (much longer than the single-qubit decoherence time). This control scheme is also shown to be robust against measurement inefficiency and individual qubit decay rate differences. Finally, the comparison of the polaron-type transformation method to the commonly used adiabatic elimination method to eliminate the cavity mode is presented.

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Shang-Yu Huang, Hsi-Sheng Goan, Xin-Qi Li, G. J. Milburn. 2013-11-25. Generation and stabilization of a three-qubit entangled W state in circuit QED via quantum feedback control. https://doi.org/10.1103/physreva.88.062311

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