Proposal for a quantum delayed-choice experiment

TL;DR

This paper introduces a framework for analyzing quantum-controlled experiments, exemplified by a quantum version of Wheeler's delayed-choice experiment, revealing new insights into quantum complementarity and the nature of wave-particle duality.

Contribution

It presents a novel framework for quantum-controlled experiments and demonstrates its implications through a quantum delayed-choice experiment, challenging classical notions of complementarity.

Findings

Quantum control enables measuring complementary phenomena simultaneously.

No hidden-variable theories can assign definite 'particle' or 'wave' properties.

Photons can exhibit a morphing behavior between 'particle' and 'wave'.

Abstract

Gedanken experiments are important conceptual tools in the quest to reconcile our classical intuition with quantum mechanics and nowadays are routinely performed in the laboratory. An important open question is the quantum behaviour of the controlling devices in such experiments. We propose a framework to analyse quantum-controlled experiments and illustrate the implications by discussing a quantum version of Wheeler's delayed-choice experiment. The introduction of a quantum-controlled device (i.e., quantum beamsplitter) has several consequences. First, it implies that we can measure complementary phenomena with a single experimental setup, thus pointing to a redefinition of complementarity principle. Second, a quantum control allows us to prove there are no consistent hidden-variable theories in which "particle" and "wave" are realistic properties. Finally, it shows that a photon can have a morphing behaviour between "particle" and "wave"; this further supports the conclusion that "particle" and "wave" are not realistic properties but merely reflect how we 'look' at the photon. The framework developed here can be extended to other experiments, particularly to Bell-inequality tests.