Generation of multiphoton quantum states on silicon

Ming Zhang,Xi-Feng Ren,Guo-Ping Guo,Lan-Tian Feng,Guang-Can Guo,Shi-Ming Gao,Yang Chen,Dao-Xin Dai,Zhi-Yuan Zhou,Hao Wu,Ming Li

doi:10.1038/s41377-019-0153-y

Abstract

Multiphoton quantum states play a critical role in emerging quantum technologies and greatly improve our fundamental understanding of the quantum world. Integrated photonics is well recognized as an attractive technology offering great promise for the generation of photonic quantum states with high-brightness, tunability, stability, and scalability. Herein, we demonstrate the generation of multiphoton quantum states using a single-silicon nanophotonic waveguide. The detected four-photon rate reaches 0.34 Hz even with a low-pump power of 600 μW. This multiphoton quantum state is also qualified with multiphoton quantum interference, as well as quantum state tomography. For the generated four-photon states, the quantum interference visibilities are greater than 95%, and the fidelity is 0.78 ± 0.02. Furthermore, such a multiphoton quantum source is fully compatible with the on-chip processes of quantum manipulation, as well as quantum detection, which is helpful for the realization of large-scale quantum photonic integrated circuits (QPICs) and shows great potential for research in the area of multiphoton quantum science.

Highlights

Multiphoton quantum sources are critical resources[1] for quantum communication[2], computation[3,4], simulation[5], and metrology[6]
The pump light went through a 100 GHz bandwidth prefilter, a polarization controller (PC), an optical circulator and was coupled into the part of the photon source with horizontal (H) polarization by controlling the PC
The Sagnac interferometer consists of two halfwave plates (HWPs), two quarter-wave plates (QWPs), a polarization beam splitter (PBS), and an ~1 cm-long silicon spiral waveguide with a simple structure as well as a compact footprint (~170 × 170 μm2)

Summary

Introduction

Multiphoton quantum sources are critical resources[1] for quantum communication[2], computation[3,4], simulation[5], and metrology[6]. Great efforts have been made for the realization of high-quality, bright, and scalable multiphoton quantum states to enable powerful implementations of quantum technologies. The efficiency of the multiplexing process decreases exponentially with the number of entangled photons; it is essential to achieve bright biphoton sources with high fidelity[9]. The strong mode confinement in optical waveguides and the filed enhancement in high-Q optical cavities can greatly enhance the nonlinear optical interactions, so that it is possible to efficiently achieve on-chip multiphoton quantum sources. Chip-based multiple indistinguishable heralded single-photon source preparation[22,23] and the generation of multiphoton quantum state with time-bin encoding[24] have been reported

Methods

Results

Conclusion