Demonstration of Scully-Dr\"uhl-type quantum erasers on quantum computers

TL;DR

This paper demonstrates a novel quantum circuit implementation of the Scully-Dürr-type quantum eraser on quantum computers, enabling controlled delayed-choice experiments with high fidelity and addressing philosophical concerns about retrocausality.

Contribution

It introduces a versatile, circuit-based quantum eraser that allows arbitrary erasure adjustments and true delayed-choice operations, improving upon traditional optical methods.

Findings

Interference patterns align with theoretical predictions despite errors

Quantum erasure achieved with delay times up to 1 microsecond

Systematic errors do not significantly affect the results

Abstract

We present a novel quantum circuit that genuinely implements the Scully-Dr\"uhl-type delayed-choice quantum eraser, where the two recorders of the which-way information directly interact with the signal qubit and remain spatially separated. Experiments conducted on IBM Quantum and IonQ processors demonstrate that the recovery of interference patterns, to varying degrees, aligns closely with theoretical predictions, despite the presence of systematic errors. This quantum circuit-based approach, more manageable and versatile than traditional optical experiments, facilitates arbitrary adjustment of the erasure and enables a true random choice in a genuine delayed-choice manner. On the IBM Quantum platform, delay gates can be employed to further defer the random choice, thereby amplifying the retrocausal effect. Since gate operations are executed sequentially in time, the system does not have any involvement of random choice until after the signal qubit has been measured, therefore eliminating any potential philosophical loopholes regarding retrocausality that might exist in other experimental setups. Remarkably, quantum erasure is achieved with delay times up to $\sim1\,\mu\text{s}$ without noticeable decoherence, a feat challenging to replicate in optical setups.