Guo Guangcan's team at CSU reveals new principle of single-photon blocking in integrated optical quantum devices

The team of academician Guangcan Guo at the University of Science and Technology of China (USTC) has made important progress in the theoretical study of integrated photonic chip quantum devices. On July 18, the results were published in the international journal Physical Review Letters under the title "Single-Mode Photon Blockade Enhanced by Bi-Tone Drive". Tone Drive" was published in Physical Review Letters, an internationally recognized journal.

Nonlinear interactions between single photons are a central resource for scalable optical quantum information processing at room temperature. However, direct observation of single-photon level photon interactions in nonlinear optical systems is extremely difficult due to the nonlinear polarizability and optical loss of materials, and therefore conventional single-photon generation methods rely mainly on probabilistic parametric down-conversion and require high pumping optical power.

Changling Zou's group has been working on integrated photonic chip quantum devices in recent years. On the integrated chip, nonlinear optical effects can be greatly enhanced by micro and nano optical structures. Based on the micro-cavity enhanced nonlinear optical effects, physical and applied research at the few-photon, or even single-photon level is carried out. Previously, the use of photonic second-order nonlinearity to achieve deterministic, high-fidelity photon-photon quantum phase gates was proposed in 2020 [Phys. Rev. Applied, 13, 044013 (2020) Editor's Recommendation], which is expected to achieve scalable quantum information processing without components such as atoms and superconducting bits at room temperature.

Recently, the international experimental research on integrated nonlinear photonics has made a rapid development, and the platforms represented by materials such as lithium niobate and indium gallium phosphide have improved the single-photon non-simplicity of optical modes to the order of 1%, providing a new way to realize weak optical quantum effects at room temperature. For example, the blocking effect of single photons can be achieved by coupling multiple microcavities to build multimode quantum interference, or by driving a single microcavity with a pulsed laser, thus filtering out single photons from coherent lasers using integrated photonic devices. However, these research schemes require complex structures, which are difficult to implement based on the existing experimental conditions. In addition, the effect of dynamical blockade in single-mode cavities is poor and the physical mechanism is not yet clear.

Figure 1. Photon blockage in a single-mode nonlinear optical cavity

To address the above challenges, the research group introduces the frequency freedom of photons and proposes to control their dynamical evolution by using two consecutive laser beams in a single optical mode. By exploiting the nonlinear cavity's non-uniform corresponding to different frequency drives, the Bouguer number distribution of different photon number states is precisely regulated at a specific time to generate sub-Poisson quantum statistical optical fields with high fidelity. Based on the reported experimental parameters of the integrated lithium niobate chip, the investigators demonstrated the experimental feasibility of the scheme.

The reviewers agreed that the study has introduced genuinely new physics and revealed the physical nature of kinetic photon blocking; it is the simplest and consumes the least resources of any reported study. It can generate antibunched light with high fidelity and minimal requirements").

Dr. Ming Li and Dr. Yanlei Zhang, Distinguished Associate Researchers of the Key Laboratory of Quantum Information, Chinese Academy of Sciences, are the co-first authors of the paper, and Prof. Changling Zou is the corresponding author. This research was supported by the Ministry of Science and Technology, the National Natural Science Foundation of China, and Anhui Province.

Article Link：

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.043601