128 Identical Quantum Sources Integrated on a Single Silica Chip

TL;DR

This paper reports the experimental integration of 128 identical quantum sources on a single silica chip, demonstrating high indistinguishability and brightness, paving the way for scalable on-chip quantum processors.

Contribution

It introduces a method to unify properties of quantum sources on a silica chip, achieving high uniformity and scalability for quantum photonic applications.

Findings

All sources exhibit over 90% Hong-Ou-Mandel interference visibility.

Sources reach MHz brightness suitable for various quantum platforms.

Scalability and uniformity enable large-scale on-chip quantum processing.

Abstract

Quantum technology is playing an increasingly important role due to the intrinsic parallel processing capabilities endorsed by quantum superposition, exceeding upper limits of classical performances in diverse fields. Integrated photonic chip offers an elegant way to construct large-scale quantum systems in a physically scalable fashion, however, nonuniformity of quantum sources prevents all the elements from being connected coherently for exponentially increasing Hilbert space. Here, we experimentally demonstrate 128 identical quantum sources integrated on a single silica chip. By actively controlling the light-matter interaction in femtosecond laser direct writing, we are able to unify the properties of waveguides comprehensively and therefore the spontaneous four-wave mixing process for quantum sources. We verify the indistinguishability of the on-chip sources by a series of heralded two-source Hong-Ou-Mandel interference, with all the dip visibilities above 90%. In addition, the brightness of the sources is found easily reaching MHz and being applicable to both discrete-variable and continuous-variable platform, showing either clear anti-bunching feature or large squeezing parameter under different pumping regimes. The demonstrated scalability and uniformity of quantum sources, together with integrated photonic network and detection, will enable large-scale all-on-chip quantum processors for real-life applications.