Can weak measurement lend empirical support to quantum retrocausality?

Yakir Aharonov, Eliahu Cohen, Doron Grossman, Avshalom C. Elitzur

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Quantum weak measurement is presented as shedding new light on the retrocausality question. It is shown to leave a system almost unaffected while gathering information about it. Next, an EPR experiment is studied where each particle undergoes a few weak measurements along some pre-set spin orientations. These weak outcomes are individually recorded. Then the particle undergoes a strong measurement along a spin orientation freely chosen at the last moment. Bell-inequality violation is expected between the two final strong measurements within each EPR pair. At the same time, agreement is expected between these strong measurements and the earlier weak ones performed on that pair. A contradiction thereby ensues: i) Bell's theorem forbids spin values to exist prior to the choice of the spin-orientation to be measured; ii) A weak measurement cannot determine the outcome of a successive strong one; and iii) Indeed no disentanglement is inflicted by the weak measurements; yet iv) The weak measurements' outcomes agree with those of the strong ones, suggesting the existence of pre-determined values. The most reasonable resolution seems to be that of the Two-State-Vector Formalism, namely, that the experimenter's choice has been encrypted within the weak measurement's outcomes, even before the experimenter themselves knows what their choice will be. Causal loops are avoided by this anticipation remaining encrypted until the final outcomes enable to decipher it.

Original languageEnglish
Title of host publicationTM 2012 - The Time Machine Factory [Unspeakable, Speakable] on Time Travel in Turin
StatePublished - 2013
EventTime Machine Factory [Unspeakable, Speakable] on Time Travel in Turin, TM 2012 - Turin, Italy
Duration: 14 Oct 201219 Oct 2012

Publication series

NameEPJ Web of Conferences
ISSN (Print)2101-6275
ISSN (Electronic)2100-014X


ConferenceTime Machine Factory [Unspeakable, Speakable] on Time Travel in Turin, TM 2012


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