A quantum emitter efficiently coupled to a nanophotonic waveguide constitutes a promising system for the realization of single-photon transistors, quantum-logic gates based on giant single-photon ...nonlinearities, and high bit-rate deterministic single-photon sources. The key figure of merit for such devices is the β factor, which is the probability for an emitted single photon to be channeled into a desired waveguide mode. We report on the experimental achievement of β=98.43%±0.04% for a quantum dot coupled to a photonic crystal waveguide, corresponding to a single-emitter cooperativity of η=62.7±1.5. This constitutes a nearly ideal photon-matter interface where the quantum dot acts effectively as a 1D "artificial" atom, since it interacts almost exclusively with just a single propagating optical mode. The β factor is found to be remarkably robust to variations in position and emission wavelength of the quantum dots. Our work demonstrates the extraordinary potential of photonic crystal waveguides for highly efficient single-photon generation and on-chip photon-photon interaction.
We present time-resolved spontaneous emission measurements of single quantum dots embedded in photonic crystal waveguides. Quantum dots that couple to a photonic crystal waveguide are found to decay ...up to 27 times faster than uncoupled quantum dots. From these measurements beta-factors of up to 0.89 are derived, and an unprecedented large bandwidth of 20 nm is demonstrated. This shows the promising potential of photonic crystal waveguides for efficient single-photon sources. The scaled frequency range over which the enhancement is observed is in excellent agreement with recent theoretical proposals taking into account that the light-matter coupling is strongly enhanced due to the significant slow-down of light in the photonic crystal waveguides.
.A numerical investigation of pulse propagation in a quantum dot structure in the regime of electromagnetically induced transparency is reported. The quantum dot is described as a cone on top of a ...wetting layer and the calculated energy levels and dipole moments are used in an effective three-level model. Pulse propagation characteristics such as degree of slowdown, absorption, and pulse distortion are investigated with respect to their dependence on the dephasing rates and pulse width. It is seen how Rabi oscillations can seriously distort the pulse when the spectral width of the pulse becomes too large compared to the width of the EIT window.
We present time-resolved spontaneous emission measurements of a single quantum dot that is temperature tuned around the band edge of a photonic crystal waveguide. 85% efficient coupling to the ...slow-light waveguide mode is obtained.
The behavior of two coupled photonic crystal membrane cavities with quantum dots separated by different number of holes is investigated. The measured spectral splitting with increased coupling is ...verified by 3D calculations and discussed.
Coherent light-matter interactions are key to a range of quantum optical technologies and experiments. We present measurements showing near-life-time limited transitions, for quantum dots embedded in ...nanoguides, demonstrating the robust suppression of environmental decoherence processes.
We have studied the transport of light through phosphor diffuser plates that are used in commercial solid-state lighting modules (Fortimo). These polymer plates contain \(\mathrm{YAG:Ce}^{+3}\) ...phosphor particles that elastically scatter light and Stokes shifts it in the visible wavelength range (400-700 nm). We excite the phosphor with a narrowband light source, and measure spectra of the outgoing light. The Stokes shifted light is separated from the elastically scattered light in the measured spectra and using this technique we isolate the elastic transmission of the plates. This result allows us to extract the transport mean free path \(l_{\mathrm{tr}}\) over the full wavelength range by employing diffusion theory. Simultaneously, we determine the absorption mean free path \(l_{\mathrm{abs}}\) in the wavelength range 400 to 530 nm where \(\mathrm{YAG:Ce}^{+3}\) absorbs. The diffuse absorption \(\mu_{\mathrm{a}} =\frac{1}{l_{\mathrm{abs}}}\) spectrum is qualitative similar to the absorption coefficient of \(\mathrm{YAG:Ce}^{+3}\) in powder, with the \(\mu_{\mathrm{a}}\) spectrum being wider than the absorption coefficient. We propose a design rule for the solid-state lighting diffuser plates.
Residual disorder due to fabrication imperfections has important impact in nanophotonics where it may degrade device performance by increasing radiation loss or spontaneously trap light by Anderson ...localization. We propose and demonstrate experimentally a method of quantifying the intrinsic amount of disorder in state-of-the-art photonic-crystal waveguides from far-field measurements of the Anderson-localized modes. This is achieved by comparing the spectral range that Anderson localization is observed to numerical simulations and the method offers sensitivity down to ~ 1 nm.
A quantum emitter efficiently coupled to a nanophotonic waveguide constitutes a promising system for the realization of single-photon transistors, quantum-logic gates based on giant single-photon ...nonlinearities, and high bit-rate deterministic single-photon sources. The key figure of merit for such devices is the \(\beta\)-factor, which is the probability for an emitted single photon to be channeled into a desired waveguide mode. We report on the experimental achievement of \(\beta = 98.43 \pm 0.04\%\) for a quantum dot coupled to a photonic-crystal waveguide, corresponding to a single-emitter cooperativity of \(\eta = 62.7 \pm 1.5\). This constitutes a nearly ideal photon-matter interface where the quantum dot acts effectively as a 1D "artificial" atom, since it interacts almost exclusively with just a single propagating optical mode. The \(\beta\)-factor is found to be remarkably robust to variations in position and emission wavelength of the quantum dots. Our work demonstrates the extraordinary potential of photonic-crystal waveguides for highly efficient single-photon generation and on-chip photon-photon interaction.
Disorder in photonic-crystal slab waveguides can cause localization of light. Sapienza et al. observed that the interaction of localized light with embedded quantum dots is so strong that it yields a ...considerable Purcell enhancement of the emission rate. This coupling between emitters and these "random cavities" warrants a more detailed investigation.
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