Can a Future Choice Affect a Past Measurement's Outcome?

TL;DR

This paper explores a quantum experiment where weak and strong measurements on entangled particles reveal a paradoxical situation, suggesting that future choices may influence past measurement outcomes, challenging classical notions of causality.

Contribution

It introduces a novel interpretation of weak measurement outcomes in EPR experiments, proposing that future measurement choices are encoded in earlier weak measurement results, supporting the Two-State-Vector Formalism.

Findings

Bell-inequality violation observed with final strong measurements

Weak measurements statistically align with strong measurement outcomes

Supports the idea of future choices influencing past measurement results

Abstract

An EPR experiment is studied where each particle within the entangled pair undergoes a few weak measurements (WMs) along some pre-set spin orientations, with the outcomes individually recorded. Then the particle undergoes one strong measurement along an orientation chosen at the last moment. Bell-inequality violation is expected between the two final measurements within each EPR pair. At the same time, statistical agreement is expected between these strong measurements and the earlier weak ones performed on that pair. A contradiction seemingly ensues: (i) Bell's theorem forbids spin values to exist prior to the choice of the orientation measured; (ii) A weak measurement is not supposed to determine the outcome of a successive strong one; and indeed (iii) Almost no disentanglement is inflicted by the WMs; and yet (iv) The outcomes of weak measurements statistically agree with those of the strong ones, suggesting the existence of pre-determined values, in contradiction with (i). Although the conflict can be solved by mere mitigation of the above restrictions, the most reasonable resolution seems to be that of the Two-State-Vector Formalism (TSVF), namely, that the choice of the experimenter has been encrypted within the weak measurement's outcomes, even before the experimenters themselves know what their choice will be.