Multi-parameter quantum metrology with discrete-time quantum walks

Abstract

We address multi-parameter quantum estimation for one-dimensional discrete-time quantum walks and its applications to quantum metrology. We use the quantum walker as a probe for unknown parameters encoded on its coin degrees of freedom. We find an analytic expression of the quantum Fisher information matrix for the most general coin operator, and show that only two out of the three coin parameters can be accessed. We also prove that the resulting two-parameter coin model is asymptotically classical i.e. the Uhlmann curvature vanishes. Finally, we apply our findings to relevant case studies, including the simultaneous estimation of charge and mass in the discretized Dirac model.

11 pages, 2 figures

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• Identifying network topologies via quantum walk distributions
• Discrete time quantum walk of locally interacting walkers
• Improving quantum walk metrology with split-step quantum walk
• Optimizing topology for quantum probing with discrete-time quantum walks