Classical field approach to quantum weak measurements

By generalizing the quantum weak measurement protocol to the case of quantum fields, we show that weak measurements probe an effective classical background field that describes the average field configuration in the spacetime region between pre- and postselection boundary conditions. The classical f...

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Bibliographic Details
Published in:Physical review letters 2014-03, Vol.112 (11), p.110407-110407, Article 110407
Main Authors: Dressel, Justin, Bliokh, Konstantin Y, Nori, Franco
Format: Article
Language:English
Subjects:
Boundary conditions
Dynamics
Equations of motion
Excitation
Operators
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Summary:By generalizing the quantum weak measurement protocol to the case of quantum fields, we show that weak measurements probe an effective classical background field that describes the average field configuration in the spacetime region between pre- and postselection boundary conditions. The classical field is itself a weak value of the corresponding quantum field operator and satisfies equations of motion that extremize an effective action. Weak measurements perturb this effective action, producing measurable changes to the classical field dynamics. As such, weakly measured effects always correspond to an effective classical field. This general result explains why these effects appear to be robust for pre- and postselected ensembles, and why they can also be measured using classical field techniques that are not weak for individual excitations of the field.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.112.110407