Centre for Quantum Photonics, H. H. Wills Physics Laboratory & Department of Electrical and Electronic Engineering, University of Bristol, Merchant Venturers Building, Woodland Road, Bristol BS8 1UB, UK.
Nat Commun. 2011;2:224. doi: 10.1038/ncomms1228.
Photonics is a leading approach in realizing future quantum technologies and recently, optical waveguide circuits on silicon chips have demonstrated high levels of miniaturization and performance. Multimode interference (MMI) devices promise a straightforward implementation of compact and robust multiport circuits. Here, we show quantum interference in a 2 × 2 MMI coupler with visibility of V=95.6 ± 0.9%. We further demonstrate the operation of a 4 × 4 port MMI device with photon pairs, which exhibits complex quantum interference behaviour. We have developed a new technique to fully characterize such multiport devices, which removes the need for phase-sensitive measurements and may find applications for a wide range of photonic devices. Our results show that MMI devices can operate in the quantum regime with high fidelity and promise substantial simplification and concatenation of photonic quantum circuits.
光子学是实现未来量子技术的主要方法，最近，硅片上的光波导电路已经展示出了高度的小型化和性能。多模干涉（MMI）器件有望实现紧凑而稳健的多端口电路的直接实现。在这里，我们在 2×2 MMI 耦合器中展示了量子干涉，其可见度为 V=95.6±0.9%。我们进一步演示了具有光子对的 4×4 端口 MMI 器件的操作，其表现出复杂的量子干涉行为。我们已经开发出一种新技术来全面表征这种多端口器件，该技术消除了对相敏测量的需求，并且可能适用于各种光子器件。我们的结果表明，MMI 器件可以在高保真度下在量子 regime 中运行，并有望大大简化和级联光子量子电路。
