Amplitude control of quantum interference

TL;DR

This paper demonstrates that controlling quantum interference oscillations can be achieved by adjusting amplitudes of quantum waves, leading to Bell violations even with many sources, expanding the methods for quantum control.

Contribution

It introduces a novel approach to quantum interference control via amplitude variation, generalizes the Hong-Ou-Mandel experiment, and shows Bell violations with multiple independent sources.

Findings

Amplitude variation induces quantum oscillations and Bell violations.

Bell violations are achievable for arbitrarily large source numbers.

Parity measurements facilitate experimental implementation.

Abstract

Usually, the oscillations of interference effects are controlled by relative phases. We show that varying the amplitudes of quantum waves, for instance by changing the reflectivity of beam splitters, can also lead to quantum oscillations and even to Bell violations of local realism. We first study theoretically a generalization of the Hong-Ou-Mandel experiment to arbitrary source numbers and beam splitter transmittivity. We then consider a Bell type experiment with two independent sources, and find strong violations of local realism for arbitrarily large source number $N$; for small $N$, one operator measures essentially the relative phase of the sources and the other their intensities. Since, experimentally, one can measure the parity of the number of atoms in an optical lattice more easily than the number itself, we assume that the detectors measure parity.