There is more to quantum interferometry than entanglement

Bromley, Thomas R., Silva, Isabela A., Oncebay-Segura, Charlie O., Soares-Pinto, Diogo O., deAzevedo, Eduardo R., Tufarelli, Tommaso and Adesso, Gerardo (2017) There is more to quantum interferometry than entanglement. Physical Review A, 95 (5). 052313/1-052313/10. ISSN 2469-9934

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Entanglement has long stood as one of the characteristic features of quantum mechanics, yet recent developments have emphasized the importance of quantumness beyond entanglement for quantum foundations and technologies. We demonstrate that entanglement cannot entirely capture the worst-case sensitivity in quantum interferometry when quantum probes are used to estimate the phase imprinted by a Hamiltonian, with fixed energy levels but variable eigenbasis, acting on one arm of an interferometer. This is shown by defining a bipartite entanglement monotone tailored to this interferometric setting and proving that it never exceeds the so-called interferometric power, a quantity which relies on more general quantum correlations beyond entanglement and captures the relevant resource. We then prove that the interferometric power can never increase when local commutativity-preserving operations are applied to qubit probes, an important step to validate such a quantity as a genuine quantum correlations monotone. These findings are accompanied by a room-temperature nuclear magnetic resonance experimental investigation, in which two-qubit states with extremal (maximal and minimal) interferometric power at fixed entanglement are produced and characterized.

Item Type: Article
Additional Information: ©2017 American Physical Society
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Mathematical Sciences
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Depositing User: Eprints, Support
Date Deposited: 10 May 2017 12:03
Last Modified: 04 May 2020 18:44

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