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arXiv · 1908.01120

Geometric pathway to scalable quantum sensing

Mattias T. Johnsson·Nabomita Roy Mukty·Daniel Burgarth·Thomas Volz·Gavin K. Brennen
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Abstract

Entangled resources enable quantum sensing that achieves Heisenberg scaling, a quadratic improvement on the standard quantum limit, but preparing large scale entangled states is challenging in the presence of decoherence. We present a quantum control strategy using highly nonlinear geometric phase gates for preparing entangled states on spin ensembles which can be used for practical precision metrology. The method uses a dispersive coupling of $N$ spins to a common bosonic mode and does not require addressability, special detunings, or interactions between the spins. Using a control sequence that executes Grover's algorithm on a subspace of permutationally symmetric states, a target entangled resource state can be prepared using $O(N^{5/4})$ geometric phase gates. The geometrically closed path of the control operations ensures the gates are insensitive to the initial state of the mode and the sequence has built-in dynamical decoupling providing resilience to dephasing errors.

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Mattias T. Johnsson, Nabomita Roy Mukty, Daniel Burgarth, Thomas Volz, Gavin K. Brennen. 2019-08-03. Geometric pathway to scalable quantum sensing. https://doi.org/10.1103/physrevlett.125.190403

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