Taming the Delayed Choice Quantum Eraser

TL;DR

The paper explains that the delayed choice quantum eraser experiment is analogous to a Bell test, showing that its paradoxes are resolved within standard quantum mechanics without invoking backwards-in-time influences.

Contribution

It provides a straightforward account of the delayed choice quantum eraser by drawing an analogy to Bell-type measurements, clarifying that no mysterious backward causation is needed.

Findings

The experiment resembles a Bell scenario, resolving apparent paradoxes.

No backwards-in-time influence is necessary to explain the results.

The de Broglie-Bohm interpretation offers a clear particle trajectory explanation.

Abstract

I discuss the delayed choice quantum eraser experiment (DCQE) by drawing an analogy to a Bell-type measurement and giving a straightforward account in standard quantum mechanics. The delayed choice quantum eraser experiment turns out to resemble a Bell-type scenario in which the paradox's resolution is rather trivial, and so there really is no mystery. At first glance, the experiment suggests that measurements on one part of an entangled photon pair (the idler) can be employed to control whether the measurement outcome of the other part of the photon pair (the signal) produces interference fringes at a screen after being sent through a double slit. Significantly, the choice whether there is interference or not can be made long after the signal photon encounters the screen. The results of the experiment have been alleged to invoke some sort of 'backwards in time influence'. I argue that this issue can be eliminated by taking into proper account the role of the signal photon. Likewise, in the de Broglie-Bohm picture the particle's trajectories can be given a well-defined description at any instant of time during the experiment. Thus, it is again clear that there is no need to resort to any kind of 'backwards in time influence'.