13 research outputs found
Topologically-protected single-photon sources with topological slow light photonic crystal waveguides
Slow light waveguides are advantageous for implementing high-performance
single-photon sources required for scalable operation of integrated quantum
photonic circuits (IQPCs), though such waveguides are known to suffer from
propagation loss due to backscattering. A way to overcome the drawback is to
use topological photonics, in which robust waveguiding in
topologically-protected optical modes has recently been demonstrated. Here, we
report single-photon sources using single quantum dots (QDs) embedded in
topological slow light waveguides based on valley photonic crystals. We observe
Purcell-enhanced single-photon emission from a QD into a topological slow light
mode with a group index over 20 and its robust propagation even under the
presence of sharp bends. These results pave the way for the realization of
robust and high-performance single-photon sources indispensable for IQPCs
Coupling of a Single Tin-vacancy Center to a Photonic Crystal Cavity in Diamond
We demonstrate optical coupling between a single tin-vacancy (SnV) center in
diamond and a free-standing photonic crystal nanobeam cavity. The cavities are
fabricated using quasi-isotropic etching and feature experimentally measured
quality factors as high as ~11,000. We investigate the dependence of a single
SnV center's emission by controlling the cavity wavelength using a
laser-induced gas desorption technique. Under resonance conditions, we observe
an intensity enhancement of the SnV emission by a factor of 12 and a 16-fold
reduction of the SnV lifetime. Based on the large enhancement of the SnV
emission rate inside the cavity, we estimate the Purcell factor for the SnV
zero-phonon line to be 37 and the coupling efficiency of the SnV center to the
cavity, the beta factor, to be 95%. Our work paves the way for the realization
of quantum photonic devices and systems based on efficient photonic interfaces
using the SnV color center in diamond
High Q-factor diamond optomechanical resonators with silicon vacancy centers at millikelvin temperatures
Phonons are envisioned as coherent intermediaries between different types of
quantum systems. Engineered nanoscale devices such as optomechanical crystals
(OMCs) provide a platform to utilize phonons as quantum information carriers.
Here we demonstrate OMCs in diamond designed for strong interactions between
phonons and a silicon vacancy (SiV) spin. Using optical measurements at
millikelvin temperatures, we measure a linewidth of 13 kHz (Q-factor of
~440,000) for 6 GHz acoustic modes, a record for diamond in the GHz frequency
range and within an order of magnitude of state-of-the-art linewidths for OMCs
in silicon. We investigate SiV optical and spin properties in these devices and
outline a path towards a coherent spin-phonon interface.Comment: 18 pages, 11 figure
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High-Q cavity interface for color centers in thin film diamond
Quantum information technology offers the potential to realize unprecedented computational resources via secure channels distributing entanglement between quantum computers. Diamond, as a host to optically-accessible spin qubits, is a leading platform to realize quantum memory nodes needed to extend such quantum links. Photonic crystal (PhC) cavities enhance light-matter interaction and are essential for an efficient interface between spins and photons that are used to store and communicate quantum information respectively. Here, we demonstrate one- and two-dimensional PhC cavities fabricated in thin-film diamonds, featuring quality factors (Q) of 1.8 × 105 and 1.6 × 105, respectively, the highest Qs for visible PhC cavities realized in any material. Importantly, our fabrication process is simple and high-yield, based on conventional planar fabrication techniques, in contrast to the previous with complex undercut processes. We also demonstrate fiber-coupled 1D PhC cavities with high photon extraction efficiency, and optical coupling between a single SiV center and such a cavity at 4 K achieving a Purcell factor of 18. The demonstrated photonic platform may fundamentally improve the performance and scalability of quantum nodes and expedite the development of related technologies
Engineering Phonon-Qubit Interactions using Phononic Crystals
The ability to control phonons in solids is key for diverse quantum
applications, ranging from quantum information processing to sensing. Often,
phonons are sources of noise and decoherence, since they can interact with a
variety of solid-state quantum systems. To mitigate this, quantum systems
typically operate at milli-Kelvin temperatures to reduce the number of thermal
phonons. Here we demonstrate an alternative approach that relies on engineering
phononic density of states, drawing inspiration from photonic bandgap
structures that have been used to control the spontaneous emission of quantum
emitters. We design and fabricate diamond phononic crystals with a complete
phononic bandgap spanning 50 - 70 gigahertz, tailored to suppress interactions
of a single silicon-vacancy color center with resonant phonons of the thermal
bath. At 4 Kelvin, we demonstrate a reduction of the phonon-induced orbital
relaxation rate of the color center by a factor of 18 compared to bulk.
Furthermore, we show that the phononic bandgap can efficiently suppress
phonon-color center interactions up to 20 Kelvin. In addition to enabling
operation of quantum memories at higher temperatures, the ability to engineer
qubit-phonon interactions may enable new functionalities for quantum science
and technology, where phonons are used as carriers of quantum information