We demonstrated the photon-number-resolving detection at 1.04 μm by coincidence frequency upconverison. The detection efficiency of 6.8% was obtained. The Poissionian distribution of the up-converted photons was observed directly.
We demonstrate photon-number-resolving detection based on coincidence frequency upconversion. Pumped by synchronized pulses, the photon signal of the coherent state at 1.04 μm was upconverted into visible replicas with preserved photon number distribution. The upconverted photons were then registered by a silicon multipixel photon counter. The photon-number-resolving performance was improved by reducing the background counts with a synchronous pump as the coincidence gate and reducing the intrinsic parametric fluorescence influence with long-wavelength pumping. A total detection efficiency of 3.7% was achieved with a quite low noise probability per pulse of 0.0002.
We experimentally demonstrate a compact synchronized fiber laser system that enables fast and efficient coincidence single-photon frequency upconversion detection. Robust synchronization between the pump and signal pulses was achieved with a long-term stability. Moreover, the synchronized pulses were wellmatching in both of the time and spectrum domains. As a result, a coincidence single-photon frequency upconversion was realized with a conversion efficiency of 91.8% and low background counts around 2.8 × 103s-1.
We have demonstrated upconversion detection at the single photon level in the 2 μm spectral window using a pump wavelength near 1550 nm, a periodically poled lithium niobate (PPLN) waveguide, and a volume Bragg grating (VBG) to reduce noise. We achieve a system photon detection efficiency of 10%, with a noise count rate of 24,500 counts per second, competitive with other 2 μm single photon detection technologies. This detector has potential applications in environmental gas monitoring, life science, and classical and quantum communication.
We demonstrate a time-resolved single-photon detection technique based on ultrafast sum-frequency generation, providing femtosecond measurement capability for single photons in photonic quantum information processing. Noncollinear broadband upconversion in periodically poled MgO-doped stoichiometric lithium tantalate with an ultrafast pump and detection with a Si single-photon counter enable efficient detection of IR photons and temporal resolution of ~150 fs. We utilize the timing resolution to map the generation efficiency profile along the propagation axis of a periodically poled KTiOPO(4) crystal, revealing its local grating quality with millimeter resolution. We also apply the technique to two-photon coincidence measurements and directly demonstrate time anticorrelation between coincident-frequency entangled photons that are parametrically generated under extended phase-matching conditions.