Experimental approaches to the quantum measurement paradox

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Jeff S. Lundeen, Aephraim M. Steinberg

It has been proposed that the ability to perform joint weak measurements on postselected systems would allow us to study quantum paradoxes. These measurements can investigate the history of those particles that contribute to the paradoxical outcome. Here we experimentally perform weak measurements of joint (i.e., nonlocal) observables. In an implementation of Hardy's paradox, we weakly measure the locations of two photons, the subject of the conflicting statements behind the paradox. Remarkably, the resulting weak probabilities verify all of these statements but, at the same time, resolve the paradox.

László E. Szabó

Ming-Cheng Chen, Chang Liu, Yi-Han Luo +7 more

We experimentally demonstrate that when three single photons transmit through two polarization channels, in a well-defined pre- and postselected ensemble, there are no two photons in the same polarization channel by weak-strength measurement, a counterintuitive quantum counting effect called the quantum pigeonhole paradox. We further show that this effect breaks down in second-order measurement. These results indicate the existence of the quantum pigeonhole paradox and its operating regime.

Jeff S. Lundeen, Aephraim M. Steinberg

Hardy's Paradox brings to light some of the striking difficulties in the interpretation of indirect quantum measurements. We weakly measure the location of the particles in Hardy's Paradox. The results provide a self-consistent resolution.

一広 横田