Significance   Quantum information science has now attracted significant attention, since it has been well proved and is believed to support quantum computation, quantum communication and quantum metrology in the near future. Characteristics of quantum states have opened the opportunities to accomplish tasks beyond classical limits, resulting in a frontier field of quantum technologies. Among them, quantum computation technology can accelerate the speed of computers exponentially with respect to the classical machine. Quantum communication technology guarantees completely secure communication, and quantum measurement technology can greatly optimize the sensitivity and/or resolution of many instruments. These potential accomplishments have led to the development of innovative and advanced applications in various fields, and therefore people are presently struggling to construct efficient quantum information systems and quantum networks. To realize practical quantum information systems and quantum networks, fundamental devices must be firstly well developed. The successful fabrication of superconductor quantum circuit chips led to an achievement of constructing quantum computer consists of 127 qubits. Realization of more general quantum computers needs much larger scaled, more robust, more quantum logic circuit chip consisting of probably superconductors, cold atoms, semiconductors, photonic crystals etc. The primary obstacles in establishing a quantum network involve the distribution of entangled qubits among nodes that are physically distant from each other, which needs high-performance entangled photon source and quantum memory. Among various types of quantum devices, optoelectronic devices play a key and central role, since the advanced microelectronic, optical and optoelectronic platforms enable fabricating the building blocks for most of the quantum information processing systems. Technologies based on optoelectronics have the potential to realize a complete product chain in the field of quantum information. This work shows the study or fabrication of optoelectronic quantum devices including single photon sources, photon entanglers, single photon detectors, quantum memories and opto-electro-mechanical sensors.

  Progress   Single photon emitters refer to the light sources that release light in the form of individual particles or photons. Single photon emitters are the fundamental devices for quantum communication. They are also well used in quantum detection and photonic quantum computation. In this direction, we have studied single photon emitters based on quantum dot (Fig.1), heralded single-photon sources (Fig.2-3), and a quantum random number generator (Fig.4). Quantum entanglement is a phenomenon that arises when a collection of particles is created, interact, or exist in close proximity to each other in such a manner that the individual quantum states of each particle cannot be figured out independently from the states of the others, even if these particles are widely separated. As a fundamental resource, quantum entangled light sources are widely used in quantum information processing. We have made a comprehensive study on the performance improvement (Fig.5-7), chip integration (Fig.8) and application (Fig.9-10) of entangled photon sources. A single photon detector is a photodetector which can respond to incident light signal as weak as one single photon. Single photon detectors play a widespread role in the field of quantum information processing since they serve as key devices for, e.g., readout in quantum computing, receiving in quantum communication and photon measurement in quantum metrology. This research is focused on specially designed single photon avalanche detectors (Fig.11), focal-plane single photon avalanche detectors (Fig.12), and negative feedback avalanche diodes (Fig.12). Moreover, we have proposed fiber Bragg grating sensing system by utilizing single photon detectors (Fig.13). In addition to the optoelectronic devices described above, we have also conducted abundant research on fiber-based quantum memory (Fig.14), optomechanical quantum device (Fig.15) and nano-opto-electro-mechanical system (Fig.16). All our studies will impact on the application of quantum technologies.

  Conclusions and Prospects   In order to realize practical quantum systems in the future, our group have made efforts to create and investigate quantum devices by using optoelectronic techniques. QD-embedded nanocavities were designed to improve the efficiency of and to realize on-demand single photon emitters. Spectral multiplexing technique enabled the fabrication of a heralded single photon source with high purity and speed, approaching on-demand single photon emitting. A quantum random number generator working at room temperature was constructed based on single photon emitting from defects in commercial GaN material. Applying cascaded second-order nonlinear optical process in PPLN waveguides, we developed an entangled photon emitter with fidelity of 97% and noise level nearly 10 times better. Chip-integrated photon entangler with visibility of over 99% was established by fabricating Si₃N₄ micro-rings via micro/nano-processing. Readout circuits were optimized to help fabricating high quality SPAD devices, and SPAD focal plane devices were improved to 128×32 array for single photon and quantum imaging. A quantum memory was achieved to simultaneously store 1 650 single photons at low temperatures, and a few opto-electro-mechanical devices were experimentally tried to obtain quantum-level measurement ability for minor quantities. Our studies might be a step forward to the realization of practical quantum information networks.