Victor Leong

Hong-Ou-Mandel interference between triggered and heralded single photons from separate atomic systems

We present Hong-Ou-Mandel interference of single photons generated via two different physical processes by two independent atomic systems: scattering by a single atom, and parametric generation via four-wave mixing in a cloud of cold atoms. Without any spectral filtering, we observe a visibility of V=62

Time-resolved scattering of a single photon by a single atom

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Diffraction-limited Fabry–Perot cavity in the near concentric regime

4%. After correcting for accidental coincidences, we obtain V=93

Photon bandwidth dependence of light-matter interaction

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Preparation of single photon states with rising exponential shape

6%. The observed interference demonstrates the compatibility of the two sources, forming the basis for an efficient quantum interface between different physical systems.

Controlling the interference of single photons emitted by independent atomic sources

We experimentally investigate the scattering of heralded photons from a single trapped atom and demonstrate that the atomic dynamics depend on whether the temporal envelope of the photon wave packet is exponentially decaying or rising.

Excitation of a single atom with a temporally shaped light pulses

Nearly concentric optical cavities can be used to prepare optical fields with a very small mode volume. We implement an anaclastic design of such a cavity that significantly simplifies mode matching to the fundamental cavity mode. The cavity is shown to have diffraction-limited performance for a mode volume of . This is in sharp contrast with the behavior of cavities with plano-concave mirrors, where aberrations significantly decrease the coupling of the input mode to the fundamental mode of the cavity and increase the coupling to the higher-order modes. We estimate the related cavity quantum electrodynamics parameters and show that the proposed cavity design allows for strong coupling without a need for high finesse or small physical-cavity volume.

2D Monte Carlo simulation of a silicon waveguide-based single-photon avalanche diode for visible wavelengths

We investigate the scattering of single photons by single atoms and, in particular, the dependence of the atomic dynamics and the scattering probability on the photon bandwidth. We tightly focus the incident photons onto a single trapped 87Rb atom and use the time-resolved transmission to characterize the interaction strength. Decreasing the bandwidth of the single photons from 6 to 2 times the atomic linewidth, we observe an increase in atomic peak excitation and photon scattering probability.

Hong-Ou-Mandel Interference Between Triggered And Heralded Single Photons From Separate Atomic Systems

We prepare single photons with a temporal envelope with rising exponential shape, resembling the time-reversed version of photons from the spontaneous decay process using a parametric conversion process in a cold atomic vapor. The mechanism is based on correlated photon pair preparation and heralding of one photon by the other one after engineering the temporal envelope of the herald.1 Such a temporal single photon profile is ideal for absorption by a two level system.2, 3 We demonstrate this in an experiment showcasing the absorption by a single Rubidium atom.4

Excitation of a single atom with a temporaly shaped light pulses

Hong-Ou-Mandel interference between independent sources is a fundamental primitive of many quantum communication and computation protocols. We present a study of the Hong-Ou-Mandel interference of single photons generated via two different physical processes by two independent atomic systems: scattering by a single atom, and parametric generation via four-wave mixing in a cloud of cold atoms. By controlling the coherence time and central frequency of the heralded single photons generated by four-wave mixing we observe quantum beat and a varying degree of interference.