Fig. 2
From: Heisenberg-scaling measurement of the single-photon Kerr non-linearity using mixed states
Experimental setup for measuring the Kerr non-linearity of a single photon. Photon pairs (with wavelengths 785 and 815 nm) are prepared through the spontaneous parametric down conversion process by pumping the BBO crystal with ultraviolet pulses. The 815 nm photons serve as triggers and the heralded 785 nm photons interact with strong probe pulses (800 nm) in an 8 m long photonic crystal fiber (PCF). The acoustic optical modulator (AOM) is used to introduce fluctuation to the probe via modulation in the intensity. After interaction, the state of the single photon is post-selected and the corresponding strong pulses are measured using a full HD oscilloscope (FHO). Analyzing the shift of average photon number of these strong pulses yields an estimation for the interaction strength. For more details, see the main text and Method. BBO -β-barium borate crystal, DM dichroic mirror, SPD: single-photon detector, HWP: half wave plate, QWP: quarter wave plate, M: mirror, FR: Faraday rotator, SF: spectral filter, PBS: polarized beam splitter, APD: amplified photon detector, CU: coincidence unit
