How Much Time Does a Measurement Take?

Author(s)

Brasil, Carlos Alexandre ^[1] ; de Castro, L. A. ^[2] ; Napolitano, R. D. J. ^[2]

Affiliation

^[1] Univ Estadual Campinas, Inst Fis Gleb Wataghin, BR-13083970 Campinas, SP - Brazil

^[2] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: FOUNDATIONS OF PHYSICS; v. 43, n. 5, p. 642-655, MAY 2013.
• Web of Science Citations: 3

Abstract

We consider the problem of measurement using the Lindblad equation, which allows the introduction of time in the interaction between the measured system and the measurement apparatus. We use analytic results, valid for weak system-environment coupling, obtained for a two-level system in contact with a measurer (Markovian interaction) and a thermal bath (non-Markovian interaction), where the measured observable may or may not commute with the system-environment interaction. Analysing the behavior of the coherence, which tends to a value asymptotically close to zero, we obtain an expression for the time of measurement which depends only on the system-measurer coupling, and which does not depend on whether the observable commutes with the system-bath interaction. The behavior of the coherences in the case of strong system-environment coupling, found numerically, indicates that an increase in this coupling decreases the measurement time, thus allowing our expression to be considered the upper limit for the duration of the process. (AU)

• FAPESP's process: 09/12460-0 - Quantum error-correction theory during logical operations and finite-duration syndrome measurements
• Grantee: Leonardo Andreta de Castro
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 11/19848-4 - Influence of the quantum measurement time on quantum information related phenomena
• Grantee: Carlos Alexandre Brasil
• Support Opportunities: Scholarships in Brazil - Post-Doctoral