Simultaneous Wavelength Translation and Amplitude Modulation of Single Photons from a Quantum Dot

Hybrid quantum information devices that combine disparate physical systems interacting through photons offer the promise of combining low-loss telecommunications wavelength transmission with high fidelity visible wavelength storage and manipulation. The realization of such systems requires control over the waveform of single photons to achieve spectral and temporal matching. Here, we experimentally demonstrate the simultaneous wavelength translation and amplitude modulation of single photons generated by a quantum dot emitting near 1300 nm with an exponentially decaying waveform (lifetime $\approx 1.5\mathrm{ns}$). Quasi-phase-matched sum-frequency generation with a pulsed 1550 nm laser creates single photons at 710 nm with a controlled amplitude modulation at 350 ps time scales.

Figure 1

Schematic of the experiment for simultaneous wavelength translation and amplitude modulation of single photons from a quantum dot.

Figure 2

(a) PL spectrum of a single QD after 60 s integration showing two excitonic transitions: $X^{+}$ (1296 nm) and $X^0$ (1297 nm). (b),(c) Second-order intensity correlation $g^{(2)}(\tau )$ of single photons up-converted with a cw pump, where $g^2(0)=0.41\pm 0.02$ (c) and a pulsed pump with ${\tau }_{\mathrm{mod}}=500\mathrm{ps}$, where $g^2(0)=0.45\pm 0.03$ (d) for an integration time of 7200 s.

Figure 3

(a),(b) Temporal profile of the up-converted photons using a cw (blue) and ${\tau }_{\mathrm{mod}}=260\mathrm{ps}$ pulsed (maroon) 1550 nm pump on linear (a) and log (b) scales. Inset: 1550 nm pump pulse measured by an optical communications analyzer. (c) The same as (a) but using a reduced timing jitter SPAD. (d) Temporal profile of up-converted photons using ${\tau }_{\mathrm{mod}}=\{0.5,1.25,2.5,5.1\}\mathrm{ns}$ along with a cw pump. All measurements are taken with 1200 s integration.

Figure 4

(a),(b) Temporal profile of the up-converted photons using a cw (blue) and ${\tau }_{\mathrm{mod}}=260\mathrm{ps}$ pulsed (various colors) 1550 nm pump on linear (a) and log (b) scales for delays $\Delta T_{\mathrm{mod}}=\{0.0,0.5,1.0,1.5,2.0,2.5,3.0,3.35\}\mathrm{ns}$. Inset: Similar measurement as (a) but measured with reduced timing jitter SPAD. All measurements are taken with 1200 s integration. (c) Net conversion efficiency and photon count rate as a function of the pump pulse FWHM ${\tau }_{\mathrm{mod}}$. Inset: Focus on the subnanosecond regime.