Noise-dependent optimal strategies for quantum metrology

Zixin Huang*, Chiara Macchiavello, Lorenzo Maccone

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


For phase estimation using qubits, we show that for some noise channels, the optimal entanglement-assisted strategy depends on the noise level. We note that there is a nontrivial crossover between the parallel-entangled strategy and the ancilla-assisted strategy: in the former the probes are all entangled; in the latter the probes are entangled with a noiseless ancilla but not among themselves. The transition can be explained by the fact that separable states are more robust against noise and therefore are optimal in the high-noise limit, but they are in turn outperformed by ancilla-assisted ones.

Original languageEnglish
Article number032333
Pages (from-to)032333-1-032333-7
Number of pages7
JournalPhysical Review A: covering atomic, molecular, and optical physics and quantum information
Issue number3
Publication statusPublished - 22 Mar 2018
Externally publishedYes


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