Quantum Photonics Research Project

Introduction

The applications of photonic quantum technology include photonic-based quantum computation, quantum communication and quantum sensing. This project aims at developing critical materials and devices for applications in photonic quantum technology. The main focus includes: (1) Single-photon emitters (SPEs), (2) Single-photon detectors (SPDs) and (3) Room-temperature quantum photonic systems, which are the fundamental building blocks in photonic quantum technology.

Laboratory contact number:02-216-7707

Principal investigator
Wen-Hao Chang whchang23@as.edu.tw

Major Milestones of the Project

  1. Developing single-photon emitters with high brightness, high efficiency, high purity and high indistinguishability.
  2. Developing superconducting nanowire single-photon detector using high quality materials to enable devices with high sensitivity, high speed, high efficiency and low noise. 
  3. Developing quantum systems that can be operating at room temperature for applications in quantum light source, quantum communications and quantum sensing. 
     

Pictures of research results

(a) TiN thin film and microwave resonator; (b) Superconducting nanowire single-photon detectors; (c) Room-temperature single-photon emitters based on SiNx/SiO2.

(a) TiN thin film and microwave resonator; (b) Superconducting nanowire single-photon detectors; (c) Room-temperature single-photon emitters based on SiNx/SiO2.

Single-Photon Emitter Achievements and Progress (I): Advancing Highly Compatible Single-Photon Emitters Enabled by Mature Semiconductor Processing. Single-defect states in wide-bandgap materials offer strong potential for quantum technologies. Using silicon-based processes, we develop SiN/SiO₂/Si trilayer single-photon emitters (SPEs) with high purity, bright zero-phonon lines, and Debye–Waller factors up to 0.74, comparable to diamond defect centers. At room temperature, these SPEs exhibit excellent optical performance. SiN films with ultra-low background fluorescence are grown by HDPCVD, followed by annealing and nitrogen incorporation to stabilize charge states and enhance emitter reliability. This approach provides a scalable and controllable platform for advancing quantum photonic devices.

Single-Photon Emitter Achievements and Progress (I): Advancing Highly Compatible Single-Photon Emitters Enabled by Mature Semiconductor Processing.

  • Single-defect states in wide-bandgap materials offer strong potential for quantum technologies. Using silicon-based processes, we develop SiN/SiO₂/Si trilayer single-photon emitters (SPEs) with high purity, bright zero-phonon lines, and Debye–Waller factors up to 0.74, comparable to diamond defect centers.
  • At room temperature, these SPEs exhibit excellent optical performance. SiN films with ultra-low background fluorescence are grown by HDPCVD, followed by annealing and nitrogen incorporation to stabilize charge states and enhance emitter reliability. This approach provides a scalable and controllable platform for advancing quantum photonic devices.
Single-Photon Emitter Achievements and Progress (II): Realizing Quantum-Entangled Photons at Telecom Wavelengths to Advance Quantum Communication Technologies. Entangled photon pairs at telecom wavelengths are essential for quantum communication, distributed quantum computing, and quantum-enhanced sensing. Reliable on-demand sources are required to overcome probabilistic emission limits, interface with quantum repeaters, and enable secure long-distance networks. In the telecom O-band (1260–1360 nm), site-controlled InAsP/InP nanowire quantum dots have been demonstrated as bright sources of single and entangled photons. Using SNSPDs and quantum state tomography, polarization entanglement was confirmed with fine-structure splitting of 4.65 μeV, Bell-state fidelity up to 85%, and concurrence of 75%. Biexciton–exciton cascades under p-shell excitation further revealed highly entangled emission. These results validate nanowire quantum dots as scalable entangled photon sources for telecom networks, with selective-area epitaxy providing precise positioning and waveguide-enhanced brightness, underscoring their strong potential for quantum communication applications.

Single-Photon Emitter Achievements and Progress (II): Realizing Quantum-Entangled Photons at Telecom Wavelengths to Advance Quantum Communication Technologies.

  • Entangled photon pairs at telecom wavelengths are essential for quantum communication, distributed quantum computing, and quantum-enhanced sensing. Reliable on-demand sources are required to overcome probabilistic emission limits, interface with quantum repeaters, and enable secure long-distance networks.
  • In the telecom O-band (1260–1360 nm), site-controlled InAsP/InP nanowire quantum dots have been demonstrated as bright sources of single and entangled photons. Using SNSPDs and quantum state tomography, polarization entanglement was confirmed with fine-structure splitting of 4.65 μeV, Bell-state fidelity up to 85%, and concurrence of 75%. Biexciton–exciton cascades under p-shell excitation further revealed highly entangled emission.
  • These results validate nanowire quantum dots as scalable entangled photon sources for telecom networks, with selective-area epitaxy providing precise positioning and waveguide-enhanced brightness, underscoring their strong potential for quantum communication applications.

Research results video