Highly pure and stable single photon source directly coupled to a fiber

Highly pure and stable single photon source is established. Well-prepared pillar array which involve InAs QDs is directly contacted to a fiber end-surface, and cooled in a liquid He bath. Auto-correlation measurement shows that it works as a highly pure single photon source providing g
⁽²⁾
(0) <; 0.1 not only in the weak excitation case but also in the moderately strong excitation one. This photon source is quite rigid against the external disturbance such as cooling-heating cycle and vibration, with a long term stability. Such a pure and stable single photon source is quite promising to build up fiber-based quantum information technology to the actual stage.