Spectrally bright and broad fiber-based heralded single-photon source

We present an experimental characterization of a heralded single-photon source based on spontaneous four-wave mixing in a single-mode microstructure fiber. We measure the second-order correlation function $g^{\left(2\right)}\left(0\right)$ to be far below the classical, Poissonian limit of 1 over a broad spectral range. With single-spatial-mode output, such a spectrally bright and broad fiber-based heralded single-photon source is suitable for a variety of quantum-information applications.

Figure 1

(Color online) Experimental setup. BS: 50:50 beam splitter.

Figure 2

(Color online) $g^{\left(2\right)}\left(0\right)$ for (a) various wavelengths at a bandwidth of $\Delta \lambda =0.9\mathrm{nm}$ and (b) various bandwidths at signal (idler) wavelength of 693 $\left(795\right)\mathrm{nm}$. Inset shows the measured Raman gain spectrum of the fiber. The lower sets of curves are heralded events and the upper sets are unheralded events. The classical, Poissonian, limit of 1 is shown as a dashed, black line. The scattered data points near the classical limit of 1 are measurements for the pulsed laser. For all points, error bars are one standard deviation and represent statistical errors. Lines are given only to guide the eye.