In the quantum optics research area, a central goal is to develop techniques for a complete control of light-matter interaction at the single-quantum level, which underlies the essential physics of many phenomena and applications. A new quantum revolution on optics and photonics is also accelerating the progress of quantum information processing (QIP), with the rapid innovation of the advanced photonic nanomaterials and processing technologies.

Recently, "chiral quantum optics" which leads to a chiral type light-matter interaction, so-called "propagation-direction-dependent" emission, has quickly attracted widespread attentions. Utilizing this kind of chiral interface, people can surely constitute an interesting quantum control of photon-emitter interaction, i.e. the nonreciprocal interaction, and furthermore fabricate a hybrid quantum system with this exciting photon-emitter setup to function some special and interesting quantum operations.

As a point defect in diamond, the nitrogen vacancy (NV) centers integrated in a hybrid quantum system have recently emerged as one of the leading candidates for QIP thanks to their excellent spin properties, such as atom-like properties, solid-state spins without any trap, optical addressable, easy scalability, and longer coherence time even at ambient conditions. In the optical-frequency domain particularly, we can conveniently fabricate the NV center with the optical cavity or optical lattice in a hybrid device, and coherently manipulate the NV center at single-quantum level with enough high efficiency.

This investigation proposed by Dr. Yuan Zhou from the quantum physics group from the School of Science, Hubei University of Automotive Technology (HUAT) in Photonics Research, Vol. 9, No. 3, 2021 (Yuan Zhou, Dong-Yan Lü, Wei-You Zeng. Chiral single-photon switch-assisted quantum logic gate with a nitrogen-vacancy center in a hybrid system[J]. Photonics Research, 2021, 9(3): 03000405) is an interesting and novel proposal for realizing a quantum logic operation and logic gate.

This hybrid system consists of a chiral switch for emitting photon pulse and an optical microcavity embedded with a single NV center, both of which are connected with an optical nanofiber

This interesting hybrid device is fabricated by a chiral photon-pulse switch, a single NV center, and an optical microcavity. For realizing this chiral photon switch, three major different practical routes are available, i.e. the "one-atom router" with cold atom scheme, "the path-encoded photon" with quantum dot system, and the "chiral photon emitter " with surface plasmon (SP) scheme.

The outputs are delivered to the optical microcavity through nanofiber in this hybrid system. A single NV center, driven by a dichromatic microwave field, is planted in the optical microcavity, which will also interact with the optical modes near-resonantly.

Besides, taking all of adverse factors into this theoretical investigation, i.e. the practical noise and experimental imperfection, this whole logic operation is evaluated numerically.

This work may be a useful attempt for implementing quantum manipulation with integrated or hybrid optical quantum devices owing to its inherent innovative and interesting nature, and may evoke wide and fruitful applications in QIP.