Efficiently Loading a Single Photon into a Single-Sided Fabry-Perot Cavity

We demonstrate that a single photon with an optimal temporal waveform can be efficiently loaded into a cavity. Using heralded narrow-band single photons with exponential growth wave packet shaped by an electro-optical amplitude modulator, whose time constant matches the photon lifetime in the cavity, we demonstrate a loading efficiency of $(87\pm 2)\%$ from free space to a single-sided Fabry-Perot cavity. We further demonstrate directly loading heralded single Stokes photons into the cavity with an efficiency of $(60\pm 5)\%$ without the electro-optical amplitude modulator and verify the time reversal between the frequency-entangled paired photons. Our result and approach may enable promising applications in realizing large-scale quantum networks based on cavity quantum electrodynamics.

Figure 1

Generating and loading heralded single photons into a cavity. (a) The single-sided Fabry-Perot cavity: $r_1=0.9955$, $r_2=0.9998$, and $L=4.625\mathrm{cm}$. (b) Experimental setup. The anti-Stokes photons are modulated by an EOAM triggered by the detection of Stokes photons at the detector $D_s$. (c) Temporal waveforms of heralded anti-Stokes photons measured as a two-photon coincidence between $D_s$ and $D_{as}$. Plot (1) is the waveform without modulation. Plot (2) shows the modulated exponential growth waveform. (d) $g_c^{(2)}$ of the heralded single anti-Stokes photons in plot (1) [panel (c)] as a function of coincidence window width.

Figure 2

Loading a single photon into a cavity with exponential growth waveforms. Panels (a)—(c) are the input single-photon exponential growth waveforms with different time constants ($1/\gamma$). Panels (d)—(f) are the corresponding cavity outputs. The coincidence counts are collected for 1800 s. (g) Loading efficiency $\eta$ as a function of the characteristic time $1/\gamma$.

Figure 3

Loading single photons with nonexponential growth waveforms: (a) An exponential decay waveform with a time constant matching the cavity lifetime, (b) a long Gaussian waveform, and (c) a short Gaussian waveform.

Figure 4

Directly loading a single photon into the cavity without EOAM. (a) [(d)]: Experimental setup for loading heralded anti-Stokes [Stokes] photons into the cavity. (b) [(e)]: Input and output temporal waveforms of heralded anti-Stokes (Stokes) photons. (c) [(f)]: $g_c^{(2)}$ of the heralded anti-Stokes (Stokes) photons as a function of the coincidence time width. The coincidence counts in (b) and (e) are collected over 300 s.