Pure and Efficient Single-Photon Sources by Shortening and Functionalizing Air-Suspended Carbon Nanotubes

A single-photon source (SPS) based on a single-walled carbon nanotube (SWCNT) is a promising candidate for uncooled on-chip quantum information optoelectronics because a single photon can be generated at both room temperature and telecommunication wavelengths on silicon chips. However, for the applications of quantum information, such as quantum computing and quantum cryptography, higher performance SPSs that exhibit both high purity and high efficiency of single-photon generation are required. Here, we theoretically propose high-performance SPSs that simultaneously achieve high-purity and high-efficiency single-photon generation by using short and functionalized air-suspended SWCNTs. The simulated exciton dynamics, time-resolved photoluminescence, and photon correlation properties indicate that exciton–exciton annihilation, end quenching, and trapping in the defect introduced by functionalization such as oxygen or aryl doping play important roles in determining the emission and single-photon properties, which strongly depend on SWCNT length and excitation intensity. We found that high performance SPSs that exhibit simultaneously high single-photon purity of 99.87% and high single-photon generation efficiency of 99.84% can be realized by using air-suspended functionalized SWCNTs with a length of approximately 100 nm under high excitation conditions. This ideal SPS can enable high rate and long-distance quantum key distributions at room temperature.