Electrical control of the uncertainty in the time of single photon emission events

We report that with appropriate voltage biasing it is possible to reduce the uncertainty in the time at which photons are emitted from a single quantum dot by an arbitrary factor. Using a resonant cavity light-emitting diode, we reduce the photon emission time jitter to one-fifth of the radiative lifetime. This enables us to demonstrate single-photon emission at a repetition rate of $1.07\mathrm{GHz}$ from both the exciton and biexciton states. This idea may lead to a new method by which pairs of indistinguishable photons can be generated for photonic quantum logic experiments.

Figure 1

(Color online) (a) Cut-away composite image based on a white-light photograph of the device. The vertical scale has been exaggerated for clarity. (b) Spectra of light emitted from the central aperture of this sample under fixed dc bias at three different voltages.

Figure 2

(Color online) Intensity of light emitted from the $X$ state as a function of time when the source is driven with nominally $300\mathrm{ps}$ long pulses at a repetition rate of $80\mathrm{MHz}$. These voltage pulses are superimposed on a fixed voltage, $V_{\mathrm{dc}}$, as illustrated in the inserts. Data are shown recorded with $V_{\mathrm{dc}}$ just below the device threshold voltage (open squares), with $V_{\mathrm{dc}}=+1.06\mathrm{V}$ (crosses) and with $V_{\mathrm{dc}}=-0.16\mathrm{V}$ (open circles). These traces are offset by a factor of 10 for clarity. The system response was also recorded using a train of $3\mathrm{ps}$ laser pulses (heavy solid line).

Figure 3

(a) Photoluminescence spectra as a function of voltage for the sample under weak optical excitation. Also shown, as a function of the applied bias, are (b) the wavelength of the $X$ state; (c) the integrated intensities of the $X$ and $X^{n+}$ state; (d) the radiative lifetimes of the $X$ and $X^{n+}$ state.

Figure 4

(a) Intensity dependence of the emission from the $X$ state when the source is driven at $1.07\mathrm{GHz}$ in the reduced-jitter mode. (b) Modeled autocorrelation histograms predicted for jitter-free classical source (dotted line) and single photon source (solid line). (c)–(h) show autocorrelation data recorded from the $X$ and $X_2$ states at different current levels with a $1.07\mathrm{GHz}$ repetition rate.