Generation of a frequency-degenerate four-photon entangled state using a silicon nanowire

Lan-Tian Feng,Guo-Ping Guo,Ming Zhang,Mark Tame,Hong-Liang Ren,Ming Li,Zhi-Yuan Zhou,Yang Chen,Guang-Can Guo,Xi-Feng Ren,Dao-Xin Dai

doi:10.1038/s41534-019-0205-4

Abstract

Integrated photonics is becoming an ideal platform for generating two-photon entangled states with high brightness, high stability, and scalability. This high brightness and high quality of photon pair sources encourages researchers further to study and manipulate multiphoton entangled states. Here, we experimentally demonstrate frequency-degenerate four-photon entangled state generation based on a single silicon nanowire 1 cm in length. The polarization encoded entangled states are generated with the help of a Sagnac loop using additional optical elements. The states are analyzed using quantum interference and state tomography techniques. As an example, we show that the generated quantum states can be used to achieve phase super-resolution. Our work provides a method for preparing indistinguishable multi-photon entangled states and realizing quantum algorithms in a compact on-chip setting.

Highlights

Entangled quantum states are useful resources for many applications in quantum information science, including quantum teleportation[1], one-way quantum computation[2,3], quantum simulation[4,5], and quantum metrology[6,7]
Integrated photonics has long been recognized as a promising platform for realizing entangled quantum states due to a low pump power requirement, high stability, and scalability[8,9], as well as showing advantages in portability for distributed quantum networks[10,11,12]
A possible route to overcome the problem of degenerate multiphoton entangled states production is using two lasers with different frequencies to pump the nonlinear material in spontaneous four-wave mixing process (SFWM)

Summary

INTRODUCTION

Entangled quantum states are useful resources for many applications in quantum information science, including quantum teleportation[1], one-way quantum computation[2,3], quantum simulation[4,5], and quantum metrology[6,7]. On the basis of high-brightness and high-quality two-photon sources, we can look further to the preparation of multiphoton quantum states In this situation, manipulating nondegenerate multiphoton quantum states with a single-pump spontaneous four-wave mixing process (SFWM) is the most direct way[17,18]. A possible route to overcome the problem of degenerate multiphoton entangled states production is using two lasers with different frequencies to pump the nonlinear material in SFWM This “dual-pump” technique was introduced in nonlinear integrated optics recently[20,21,22,23,24,25], and has provided advantages over the single-pump process in quantum state manipulation[25,26,27]. Our approach could be further integrated and potentially used for preparing indistinguishable multiphoton entangled states and realizing quantum algorithms in a compact on-chip setting

Experimental setup

DISCUSSION

METHODS