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Measurability of Wilson loop operators

Beckman, David and Gottesman, Daniel and Kitaev, Alexei and Preskill, John (2002) Measurability of Wilson loop operators. Physical Review D, 65 (6). Art. no. 065022. ISSN 0556-2821. http://resolver.caltech.edu/CaltechAUTHORS:BECprd02

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Abstract

We show that the nondemolition measurement of a spacelike Wilson loop operator W(C) is impossible in a relativistic non-Abelian gauge theory. In particular, if two spacelike-separated magnetic flux tubes both link with the loop C, then a nondemolition measurement of W(C) would cause electric charge to be transferred from one flux tube to the other, a violation of relativistic causality. A destructive measurement of W(C) is possible in a non-Abelian gauge theory with suitable matter content. In an Abelian gauge theory, many cooperating parties distributed along the loop C can perform a nondemolition measurement of the Wilson loop operator if they are equipped with a shared entangled ancilla that has been prepared in advance. We also note that Abelian electric charge (but not non-Abelian charge) can be transported superluminally, without any accompanying transmission of information.


Item Type:Article
Additional Information:©2002 The American Physical Society Received 23 October 2001; published 5 March 2002 We thank Steve Giddings, Anton Kapustin, Michael Nielsen, Edward Witten, and especially Mark Srednicki for helpful discussions and comments. This work was supported in part by the Department of Energy under Grant No. DEFG03-92-ER40701, by the National Science Foundation under Grant No. EIA-0086038, by the Caltech MURI Center for Quantum Networks under ARO Grant No. DAAD19-00-1-0374, by IBM, and by the Clay Mathematics Institute. Some of this work was done at the Aspen Center for Physics.
Record Number:CaltechAUTHORS:BECprd02
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:BECprd02
Alternative URL:http://dx.doi.org/10.1103/PhysRevD.65.065022
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1238
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:05 Jan 2006
Last Modified:26 Dec 2012 08:43

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