How Difficult is it to Prepare a Quantum State?

Journal Article · 10 January 2019 · Physical Review Letters

DOI: https://doi.org/10.1103/PhysRevLett.122.010505 · OSTI ID:1492616

Girolami, Davide  ^[1]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of California, Santa Barbara, CA (United States)

Consider a quantum system prepared in an input state. One wants to drive it into a target state. Assuming classical states and operations as free resources, I identify a geometric cost function which quantifies the difficulty of the protocol in terms of how different it is from a classical process. The quantity determines a lower bound to the number of commuting unitary transformations required to complete the task. Lastly, I then discuss the link between the quantum character of a state preparation and the amount of coherence and quantum correlations that are created in the target state.

• Research Organization: Los Alamos National Laboratory (LANL)
• Sponsoring Organization: Laboratory Directed Research and Development (LDRD); USDOE
• Grant/Contract Number: 89233218CNA000001
• OSTI ID: 1492616
• Report Number(s): LA-UR-18-27400
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 1 Vol. 122; ISSN 0031-9007; ISSN PRLTAO
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English