A search algorithm for quantum state engineering and metrology

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In this paper we present a search algorithm that finds useful optical quantum states which can be created with current technology.

• We apply the algorithm to the field of quantum metrology with the goal of finding states that can measure a phase shift to a high precision.
• Our algorithm efficiently produces a number of novel solutions: we find experimentally-ready schemes to produce states that show significant improvements over the state-of-the-art, and can measure with a precision that beats the shot noise limit by over a factor of 4.
• Furthermore, these states demonstrate a robustness to moderate/high photon losses, and we present a conceptually simple measurement scheme that saturates the Cram\'er-Rao bound.