8 research outputs found
Engineering chiral light-matter interaction in photonic crystal waveguides with slow light
We design photonic crystal waveguides with efficient chiral light--matter
interfaces that can be integrated with solid-state quantum emitters. By using
glide-plane-symmetric waveguides, we show that chiral light-matter interaction
can exist even in the presence of slow light with slow-down factors of up to
and therefore the light--matter interaction exhibits both strong Purcell
enhancement and chirality. This allows for near-unity directional
-factors for a range of emitter positions and frequencies. Additionally,
we design an efficient mode adapter to couple light from a standard nanobeam
waveguide to the glide-plane symmetric photonic crystal waveguide. Our work
sets the stage for performing future experiments on a solid-state platform
Narrow optical linewidths and spin pumping on charge-tunable close-to-surface self-assembled quantum dots in an ultrathin diode
We demonstrate full charge control, narrow optical linewidths, and optical spin pumping on single self-assembled InGaAs quantum dots embedded in a 162.5ânm-thin diode structure. The quantum dots are just 88nm from the top GaAs surface. We design and realize a pâiânâiân diode that allows single-electron charging of the quantum dots at close-to-zero applied bias. In operation, the current flow through the device is extremely small resulting in low noise. In resonance fluorescence, we measure optical linewidths below 2ÎźeV, just a factor of 2 above the transform limit. Clear optical spin pumping is observed in a magnetic field of 0.5T in the Faraday geometry. We present this design as ideal for securing the advantages of self-assembled quantum dotsâhighly coherent single-photon generation, ultrafast optical spin manipulationâin the thin diodes required in quantum nanophotonics and nanophononics applications
Indistinguishable and efficient single photons from a quantum dot in a planar nanobeam waveguide
We demonstrate a high-purity source of indistinguishable single photons using a quantum dot embedded in a nanophotonic waveguide. The source features a near-unity internal coupling efficiency and the collected photons are efficiently coupled off chip by implementing a taper that adiabatically couples the photons to an optical fiber. By quasiresonant excitation of the quantum dot, we measure a single-photon purity larger than 99.4% and a photon indistinguishability of up to 94Âą1% by using p-shell excitation combined with spectral filtering to reduce photon jitter. A temperature-dependent study allows pinpointing the residual decoherence processes, notably the effect of phonon broadening. Strict resonant excitation is implemented as well as another means of suppressing photon jitter, and the additional complexity of suppressing the excitation laser source is addressed. The paper opens a clear pathway towards the long-standing goal of a fully deterministic source of indistinguishable photons, which is integrated on a planar photonic chip
Chiral quantum optics
At the most fundamental level, the interaction between light and matter is
manifested by the emission and absorption of single photons by single quantum
emitters. Controlling light--matter interaction is the basis for diverse
applications ranging from light technology to quantum--information processing.
Many of these applications are nowadays based on photonic nanostructures
strongly benefitting from their scalability and integrability. The confinement
of light in such nanostructures imposes an inherent link between the local
polarization and propagation direction of light. This leads to {\em chiral
light--matter interaction}, i.e., the emission and absorption of photons depend
on the propagation direction and local polarization of light as well as the
polarization of the emitter transition. The burgeoning research field of {\em
chiral quantum optics} offers fundamentally new functionalities and
applications both for single emitters and ensembles thereof. For instance, a
chiral light--matter interface enables the realization of integrated
non--reciprocal single--photon devices and deterministic spin--photon
interfaces. Moreover, engineering directional photonic reservoirs opens new
avenues for constructing complex quantum circuits and networks, which may be
applied to simulate a new class of quantum many--body systems
Deterministic photon-emitter coupling in chiral photonic circuits
The ability to engineer photon emission and photon scattering is at the heart
of modern photonics applications ranging from light harvesting, through novel
compact light sources, to quantum-information processing based on single
photons. Nanophotonic waveguides are particularly well suited for such
applications since they confine photon propagation to a 1D geometry thereby
increasing the interaction between light and matter. Adding chiral
functionalities to nanophotonic waveguides lead to new opportunities enabling
integrated and robust quantum-photonic devices or the observation of novel
topological photonic states. In a regular waveguide, a quantum emitter radiates
photons in either of two directions, and photon emission and absorption are
reverse processes. This symmetry is violated in nanophotonic structures where a
non-transversal local electric field implies that both photon emission and
scattering may become directional. Here we experimentally demonstrate that the
internal state of a quantum emitter determines the chirality of single-photon
emission in a specially engineered photonic-crystal waveguide. Single-photon
emission into the waveguide with a directionality of more than 90\% is observed
under conditions where practically all emitted photons are coupled to the
waveguide. Such deterministic and highly directional photon emission enables
on-chip optical diodes, circulators operating at the single-photon level, and
deterministic quantum gates. Based on our experimental demonstration, we
propose an experimentally achievable and fully scalable deterministic
photon-photon CNOT gate, which so far has been missing in photonic
quantum-information processing where most gates are probabilistic.Comment: The revised manuscript has been significantly updated and the
experimental demonstration of chiral emission has been include