Testing multi-photon interference on a silicon chip

Abstract

Multi-photon interference in large multi-port interferometers is key to linear optical quantum computing and in particular to boson sampling. Silicon photonics enables complex interferometric circuits with many components in a small footprint and has the potential to extend these experiments to larger numbers of interfering modes. However, loss has generally limited the implementation of multi-photon experiments in this platform. Here, we make use of high-efficiency grating couplers to combine bright and pure quantum light sources based on ppKTP waveguides with silicon circuits. We interfere up to 5 photons in up to 15 modes, verifying genuine multi-photon interference by comparing the results against various models including partial distinguishability between photons.

Two-boson quantum interference in time

“…More generally, the interference of many photons scattered over many modes in a linear optical network has generated a tremendous interest in the recent years, given the connection with the "boson sampling" problem [i.e., the hardness of computing the permanent of a random matrix (29)], and technological progress in integrated optics now makes it possible to access large optical circuits (see, e.g., ref. 30). In this context, it would be exciting to uncover new consequences of PTR duality and time-like interference.…”

Two-boson quantum interference in time

“…Observing timelike two-photon interference in experiments involving active optical components would then be a highly valuable metrology tool given that the HOM dip is commonly used today as a method to benchmark the reliability of single-particle sources and mode matching. More generally, the interference of many photons scattered over many modes in a linear optical network has generated a tremendous interest in the recent years, given the connection with the "boson sampling" problem, i.e., the hardness of computing the permanent of a random matrix [29], and technological progress in integrated optics now makes it possible to access large optical circuits (see, e.g., [30]). In this context, it would be exciting to uncover new consequences of PTR duality and timelike interference.…”

Reducing $g^{(2)}(0)$ of a parametric down-conversion source via photon-number resolution with superconducting nanowire detectors

“…𝑛 → 0, to minimize the contribution of such higher order-terms [14][15][16]. The increasing demand for higher photon rates to conduct experiments involving a growing number of photons [17][18][19] restricts the possibility of working in this regime. This presents a clear trade-off between photon statistics free from multiphoton noise and detection rates.…”