1,445 research outputs found

    Some Quantum Dynamical Semi-groups with Quantum Stochastic Dilation

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    We consider the GNS Hilbert space H\mathcal{H} of a uniformly hyper-finite CC^*- algebra and study a class of unbounded Lindbladian arises from commutators. Exploring the local structure of UHF algebra, we have shown that the associated Hudson-Parthasarathy type quantum stochastic differential equation admits a unitary solution. The vacuum expectation of homomorphic co-cycle, implemented by the Hudson-Parthasarathy flow, is conservative and gives the minimal semi-group associated with the formal Lindbladian. We also associate conservative minimal semi-groups to another class of Lindbladian by solving the corresponding Evan-Hudson equation

    Multi-Qubit Joint Measurements in Circuit QED: Stochastic Master Equation Analysis

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    We derive a family of stochastic master equations describing homodyne measurement of multi-qubit diagonal observables in circuit quantum electrodynamics. In the regime where qubit decay can be neglected, our approach replaces the polaron-like transformation of previous work, which required a lengthy calculation for the physically interesting case of three qubits and two resonator modes. The technique introduced here makes this calculation straightforward and manifestly correct. Using this technique, we are able to show that registers larger than one qubit evolve under a non-Markovian master equation. We perform numerical simulations of the three-qubit, two-mode case from previous work, obtaining an average post-measurement state fidelity of 94%\sim 94\%, limited by measurement-induced decoherence and dephasing.Comment: 22 pages, 9 figures. Comments welcom