We address metrological problems where the parameter of interest is encoded in the internal degree of freedom of a discrete-time quantum walker, and provide evidence that coin dimensionality is a potential resource to enhance precision. In particular, we consider estimation problems where the coin parameter governs rotations around a given axis and show that the corresponding quantum Fisher information (QFI) may increase with the dimension of the coin. We determine the optimal initial state of the walker to maximize the QFI and discuss whether, and to what extent, precision enhancement may be achieved by measuring only the position of the walker. Finally, we consider Grover-like encoding of the parameter and compare results with those obtained from rotation encoding.
Coin dimensionality as a resource in quantum metrology involving discrete-time quantum walks / Cavazzoni, Simone; Razzoli, Luca; Ragazzi, Giovanni; Bordone, Paolo; Paris, Matteo G. A.. - In: PHYSICAL REVIEW A. - ISSN 2469-9926. - 109:2(2024), pp. 022432-1-022432-14. [10.1103/PhysRevA.109.022432]
Coin dimensionality as a resource in quantum metrology involving discrete-time quantum walks
Simone Cavazzoni
;Giovanni Ragazzi;Paolo Bordone;
2024
Abstract
We address metrological problems where the parameter of interest is encoded in the internal degree of freedom of a discrete-time quantum walker, and provide evidence that coin dimensionality is a potential resource to enhance precision. In particular, we consider estimation problems where the coin parameter governs rotations around a given axis and show that the corresponding quantum Fisher information (QFI) may increase with the dimension of the coin. We determine the optimal initial state of the walker to maximize the QFI and discuss whether, and to what extent, precision enhancement may be achieved by measuring only the position of the walker. Finally, we consider Grover-like encoding of the parameter and compare results with those obtained from rotation encoding.File | Dimensione | Formato | |
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