Advancement of estimation fidelity in continuous quantum measurement

Abstract

We estimate an unknown qubit from the long sequence of n random polarization measurements of precision Delta. Using the standard Ito-stochastic equations of the aposteriori state in the continuous measurement limit we calculate the advancement of fidelity. We show that the standard optimum value 2/3 is achieved asymptotically for n >> Delta^2 / 96 >> 1. We append a brief derivation of novel Ito-equations for the estimate state.

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References in corpus (4)

• Continuous quantum measurement and Itô formalism
• Fidelity balance in quantum operations
• A sequence of unsharp measurements enabling a real time visualization of a quantum oscillation
• Density matrix purification due to continuous quantum measurement

Cited by in corpus (4)

• Non-Markovian Toy Quantum Chain
• Coupled Ito equations of continuous quantum state measurement, and estimation
• Estimating the post-measurement state
• Single qubit estimation from repeated unsharp measurements