Single-photon nonlinear optics with a semiconductor quantum dot

Frank Bello, D. Sanvitto, Fabrice P. Laussy +6 more

Stephen Hughes, C. Roy

L.M. Wells, Sokratis Kalliakos, B. Villa +6 more

Quantum-dot-based nonlinearities are an important building block for logic operations in quantum information processing. The authors build on theoretical proposals by using the nonlinear effects of a spin-photon interaction and measuring the resultant phase shifts of scattered light pulses induced by a semiconductor quantum dot. Phase rotations of almost 80\ifmmode^\circ\else\textdegree\fi{} are achieved at the single-photon level, and phase switching is demonstrated. These findings highlight the importance of semiconductor quantum dots as a nonlinear medium for developing quantum information processing and quantum photonic integrated circuits.

Rudolf Bratschitsch, Alfred Leitenstorfer

In conclusion, we have presented a semiconductor quantum dot as a solid-state system to perform femtosecond quantum optics experiments. The ultrafast dynamics in a single semiconductor quantum dot reveals instantaneous Coulomb renormalization, perturbed free induction decay, and unexpected single-photon gain. It is now possible to prepare, manipulate, and readout this single-electron system on a femtosecond timescale. When driving the dot in the nonlinear regime, it is possible to add single photons to a femtosecond laser pulse. Finally, we have demonstrated means of increasing the coupling of light with objects of nanometer dimensions. We presented dielectric microcavities operating both in the visible and ultraviolet. Alternatively, metal nanoantennas were fabricated. They work as optical counterparts of the well-known radio antennas and concentrate light in the antenna feedgap. We have demonstrated a tunable bowtie nanoantenna and investigated its linear optical properties. We believe that progress in nanotechnology in the next years will further enable us to tailor the interaction of light with single nanoemitters to enter the regime of few-photon femtosecond physics.

A. S. Parkins, Daniel F. Walls, Ataç İmamoğlu

P.-L. Ardelt, M. Koller, Tobias Simmet +7 more

We report nonlinear resonance fluorescence of an individual semiconductor quantum dot. By driving a single semiconductor quantum dot via a two-photon transition, we probe the linewidth of two-photon excitation processes and show that, similar to their single-photon counterparts, they are close to being Fourier limited at low temperatures. The evolution of the population of excitonic states with increasing Rabi energy exhibits a clear S-shaped behavior, indicative of the nonlinear response via the two-photon excitation process. Numerical calculations of the nonlinear response using a four-level atomic system representing the manifold of excitonic and biexcitonic states in the quantum dot are in excellent agreement with our experiments and reveal the effect of interactions with LA phonons in the solid-state environment. Finally, we demonstrate the formation of dressed states emerging from a nonlinear two-photon interaction between the quantum dot and the optical excitation field. The nonlinear optical dressing induces a mixing of all four excitonic states that allows direct optical tuning of the polarization selection rules and energies of the dressed states in the artificial atom. We expect our results to play a pivotal role for the generation of nonclassical photon pairs desired for applications in quantum communication and fundamental experiments on quantum optical properties of photons.