arXiv subjects

H. Thyrrestrup

Publications and source records attributed to H. Thyrrestrup.

5 recordsLinked to original sources

arXiv2025

Deterministic quantum dot single-photon sources: operational principles and state-of-the-art specifications

Non-classical states of light play a fundamental role in quantum technology. From photonic quantum computers and simulators, to quantum communication and sensing, quantum states of light enable performing tasks that may outperform their best classical counterparts. Semiconductor quantum dots embedded in photonic nanostructures offer the most advanced classes of quantum light sources. Importantly, the underlying physics processes determining device performance are today fully understood, and dedicated engineering projects are currently advancing these sources towards real-world quantum technology applications. We review the performance of deterministic single-photon sources based on quantum dots in photonic crystal waveguides, the approach with the highest performance specs since it intrinsically combines suppression of leaky modes and Purcell enhancement to slow-light waveguide mode. Furthermore, we present prototype data from sources that today are commercially available and with performance metrics approaching the ideal.

physics.optics↗

arXiv2015

How to distinguish elastically scattered light from Stokes shifted light for solid-state lighting?

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 $μ_{\mathrm{a}} =\frac{1}{l_{\mathrm{abs}}}$ spectrum is qualitative similar to the absorption coefficient of $\mathrm{YAG:Ce}^{+3}$ in powder, with the $μ_{\mathrm{a}}$ spectrum being wider than the absorption coefficient. We propose a design rule for the solid-state lighting diffuser plates.

physics.optics↗

arXiv2014

Near-unity coupling efficiency of a quantum emitter to a photonic-crystal waveguide

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 $β= 98.43 \pm 0.04\%$ for a quantum dot coupled to a photonic-crystal waveguide, corresponding to a single-emitter cooperativity of $η= 62.7 \pm 1.5$. 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 $β$-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.

quant-ph↗

arXiv2012

Quantifying the intrinsic amount of fabrication disorder in photonic-crystal waveguides from optical far-field intensity measurements

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.

physics.optics↗

arXiv2008

Experimental realization of highly-efficient broadband coupling of single quantum dots to a photonic crystal waveguide

We present time-resolved spontaneous emission measurements of single quantum dots embedded in photonic crystal waveguides. Quantum dots that couple to the photonic crystal waveguide are found to decay up to 27 times faster than uncoupled quantum dots. From these measurements $β$-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 where the enhancement is observed is in excellent agreement with theory taking into account that the light-matter coupling is strongly enhanced due to the significant slow-down of light in the photonic crystal waveguide.

quant-ph↗