Europhys. Lett.
Volume 47, Number 4, August 1999
Page(s) 407 - 413
Section General
Published online 01 September 2002
DOI: 10.1209/epl/i1999-00403-3

Europhys. Lett, 47 (4), pp. 407-413 (1999)

Are violations to temporal Bell inequalities there when somebody looks?

T. Calarco 1, M. Cini 2 and R. Onofrio 3

1 Institut für Theoretische Physik, Universität Innsbruck
Technikerstraße 25/2 - 6020 Innsbruck, Austria
ECT*, European Centre forTheoretical Studies in Nuclear Physics and Related Areas
Strada delle Tabarelle 286, 38050 Villazzano (Trento), Italy
2 Dipartimento di Fisica, Università di Roma "La Sapienza''
INFN, Sezione di Roma - P.le Aldo Moro 2, 00185 Roma, Italy
3 Dipartimento di Fisica "G. Galilei'', Università di Padova
Via Marzolo 8, 35131 Padova, Italy
INFM, Sezione di Roma 1 - P.le Aldo Moro 2, 00185 Roma, Italy

(received 21 September 1998; accepted in final form 25 June 1999)

PACS. 03.65Bz - Foundations, theory of measurement, miscellaneous theories (including
Aharonov-Bohm effect, Bell inequalities, Berry's phase).
PACS. 42.50Lc - Quantum fluctuations, quantum noise, and quantum jumps.
PACS. 85.25Dq - Superconducting quantum interference devices (SQUIDs).


The possibility of observing violations of temporal Bell inequalities, originally proposed by Leggett and Garg as a mean of testing the quantum-mechanical delocalization of suitably chosen macroscopic bodies, is discussed by taking into account the effect of the measurement process. A general criterion quantifying this possibility is defined and shown not to be fulfilled by the various experimental configurations proposed so far to test inequalities of different forms.


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