Quantum Optical Waveform Conversion

Proposals for long-distance quantum communication rely on the entanglement of matter-based quantum nodes through optical communications channels, but the entangling light pulses have poor temporal behavior in current experiments. Here we show that nonlinear mixing of a quantum light pulse with a spectrally tailored classical field can compress the quantum pulse by more than a factor of 100 and flexibly reshape its temporal waveform while preserving all quantum properties, including entanglement. Our scheme paves the way for quantum communication at the full data rate of optical telecommunications.

Figure 1

Scheme for quantum optical waveform conversion. The colors under the pulse envelope accurately represent the frequency variation during the pulse length, with the variation of colors greatly exaggerated for clarity.

Figure 2

(a) Escort phase modulation function $\varphi (z)$ and (b) recompression phase modulation function $\gamma (k)$ for conversion from a single-sided exponential waveform to a Gaussian waveform with compression ratio $\tau /\sigma =100$.

Figure 3

Dispersive error induced by quantum waveform conversion. (a) Case 1 of the text. Solid line: perturbative prediction. Points: simulation results. Dashed line: best fit of $1-F=(u/u_{\mathrm{err}}{)}^2$ to simulation points. (b) Error scale $u_{\mathrm{err}}$ as a function of compression ratio $\tau /\sigma$. Solid line: perturbative prediction. Points: simulated values computed from least-squares fits to simulation results. Panels (c) and (d) are the same as (a) and (b) but for case 2 of the text.