Past of a quantum particle

L. Vaidman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

149 Scopus citations

Abstract

Although there is no consensus regarding the "reality" of the past of a quantum particle, in situations where there is only one trajectory with a nonvanishing quantum wave of the particle between its emission and detection points, it seems "safe" to associate the past of the particle with this trajectory. A method for analyzing the past of a quantum particle according to the weak trace it leaves is proposed. Such a trace can be observed via measurements performed on an ensemble of identically pre- and postselected particles. Examples in which this method contradicts the above common sense description of the past of the particle are presented. It is argued that it is possible to describe the past of a quantum particle, but the naive approach has to be replaced by both forward- and backward-evolving quantum states.

Original languageEnglish
Article number052104
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Volume87
Issue number5
DOIs
StatePublished - 3 May 2013

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