Quantum Fisher information as a predictor of decoherence in the preparation of spin-cat states for quantum metrology

Nolan, Samuel and Haine, Simon (2017) Quantum Fisher information as a predictor of decoherence in the preparation of spin-cat states for quantum metrology. Physical Review A, 95 (4). 043642. ISSN 2469-9926

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Abstract

In its simplest form, decoherence occurs when a quantum state is entangled with a second state, but the results of measurements made on the second state are not accessible. As the second state has effectively “measured” the first, in this paper we argue that the quantum Fisher information is the relevant metric for predicting and quantifying this kind of decoherence. The quantum Fisher information is usually used to determine an upper bound on how precisely measurements on a state can be used to estimate a classical parameter, and as such it is an important resource. Quantum-enhanced metrology aims to create nonclassical states with large quantum Fisher information and utilize them in precision measurements. In the process of doing this it is possible for states to undergo decoherence; for instance atom-light interactions used to create coherent superpositions of atomic states may result in atom-light entanglement. Highly nonclassical states, such as spin-cat states (Schrödinger cat states constructed from superpositions of collective spins) are shown to be highly susceptible to this kind of decoherence. We also investigate the required field occupation of the second state, such that this decoherence is negligible.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Mathematics
Research Centres and Groups: Atomic, Molecular and Optical Physics Research Group
Depositing User: Simon Haine
Date Deposited: 21 Jul 2017 13:02
Last Modified: 21 Jul 2017 13:09
URI: http://sro.sussex.ac.uk/id/eprint/69378

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Project NameSussex Project NumberFunderFunder Ref
QBASG1862European Commission704672