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arXiv · 1005.2470

Joint quantum nondemolition measurements of qubits: beyond the mean-field theory

L. F. Wei·J. S. Huang·X. L. Feng·Z. D. Wang·C. H. Oh
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Abstract

We propose an approach to nondestructively detect $N$ qubits by measuring the transmissions of a dispersively-coupled cavity. By taking into account all the cavity-qubits quantum correlations (i.e., beyond the usual coarse-grained/mean-field approximations), it is revealed that for an unknown normalized $N$-qubit state $|\psi_N>=\sum_{k=0}^{2^N-1}\beta_k|k>_N$, each detected peak in the cavity transmitted spectra marks one of the basis states $|k>_N$ and the relative height of such a peak is related to the corresponding superposed-probability $|\beta_k|^2$. Our results are able to unambiguously account for the intriguing multi-peak structures of the spectra observed in a very recent circuit-quantum-electrodynamics experiment [Phys. Rev. A {\bf 81}, 062325 (2010)] with two superconducting qubits.

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L. F. Wei, J. S. Huang, X. L. Feng, Z. D. Wang, C. H. Oh. 2010-05-14. Joint quantum nondemolition measurements of qubits: beyond the mean-field theory. https://arxiv.org/abs/1005.2470

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