Ultrabright room-temperature single-photon emission from nanodiamond nitrogen-vacancy centers with sub-nanosecond excited-state lifetime
Simeon Bogdanov, Mikhail Y. Shalaginov, Alexei Lagutchev, Chin‐Cheng Chiang, Deesha Shah, Baburin, Alexander S., Ilya A. Ryzhikov, Ilya A. Rodionov, Alexandra E. Boltasseva, Vladimir M. Shalaev
Ultrafast emission rates obtained from quantum emitters coupled to plasmonic nanoantennas have recently opened fundamentally new possibilities in quantum information and sensing applications. Plasmonic nanoantennas greatly improve the brightness of quantum emitters by dramatically shortening their fluorescence lifetimes. Gap plasmonic nanocavities that support strongly confined modes are of particular interest for such applications. We demonstrate single-photon emission from nitrogen-vacancy (NV) centers in nanodiamonds coupled to nanosized gap plasmonic cavities with internal mode volumes about 10 000 times smaller than the cubic vacuum wavelength. The resulting structures features sub-nanosecond NV excited-state lifetimes and detected photon rates up to 50 million counts per second. Analysis of the fluorescence saturation allows the extraction of the multi-order excitation rate enhancement provided by the nanoantenna. Efficiency analysis shows that the NV center is producing up to 0.25 billion photons per second in the far-field.
Ultrafast emission rates obtained from quantum emitters coupled to plasmonic nanoantennas have recently opened fundamentally new possibilities in quantum information and sensing applications. Plasmonic nanoantennas greatly improve the brightness of quantum emitters by dramatically shortening their fluorescence lifetimes. Gap plasmonic nanocavities that support strongly confined modes are of particular interest for such applications. We demonstrate single-photon emission from nitrogen-vacancy (NV) centers in nanodiamonds coupled to nanosized gap plasmonic cavities with internal mode volumes about 10 000 times smaller than the cubic vacuum wavelength. The resulting structures features sub-nanosecond NV excited-state lifetimes and detected photon rates up to 50 million counts per second. Analysis of the fluorescence saturation allows the extraction of the multi-order excitation rate enhancement provided by the nanoantenna. Efficiency analysis shows that the NV center is producing up to 0.25 billion photons per second in the far-field.
Solid-state quantum emitters are in high demand for emerging technologies such as advanced sensing and quantum information processing. Generally, these emitters are not sufficiently bright for practical applications, and a promising solution consists in coupling them to plasmonic nanostructures. Plasmonic nanostructures support broadband modes, making it possible to speed up the fluorescence emission in room-temperature emitters by several orders of magnitude. However, one has not yet achieved such a fluorescence lifetime shortening without a substantial loss in emission efficiency, largely because of strong absorption in metals and emitter bleaching. Here, we demonstrate ultrabright single-photon emission from photostable nitrogen-vacancy (NV) centers in nanodiamonds coupled to plasmonic nanocavities made of low-loss single-crystalline silver. We observe a 70-fold difference between the average fluorescence lifetimes and a 90-fold increase in the average detected saturated intensity. The nanocavity-coupled NVs produce up to 35 million photon counts per second, several times more than the previously reported rates from room-temperature quantum emitters.
Single-photon sources are essential for quantum technologies, supporting secure communication, quantum computing, and integrated photonic systems. Nitrogen-vacancy (NV) centers in nanodiamonds are robust emitters that operate at room temperature and can be positioned on-chip, but efficient coupling to photonic modes remains challenging. We present the design, fabrication, and experimental characterization of a silicon nitride photonic structure engineered to enhance and extract emission from NV centers. The device features a subwavelength gap between waveguides, a Bragg reflector for emission redirection, and an output waveguide for collection. Simulations guided the optimization of the geometry to increase the spontaneous emission rate through photonic confinement. Nanodiamonds were deposited into the gap using lithographic patterning and drop-casting. Fluorescence lifetime measurements confirm that the structure modifies the emission dynamics of the NV centers. The approach is compatible with scalable fabrication techniques and offers a practical route toward integrated, chip-based single-photon sources.
The nitrogen vacancy center in diamond in its negative charge state is a promising candidate for quantum optic experiments that require single photon emitters. Important benefits of the NV center are its high brightness and photo-stability, even at room temperature. Engineering the emission properties of NV centers with optical resonators is a widely followed approach to meet the requirements for quantum technological applications, but the effect on non-radiative decay paths is yet to be understood. Here we report on modifying the internal quantum efficiency of a single NV center in a nanodiamond coupled to a 1D photonic crystal cavity. We assess the Purcell enhancement via three independent measurement techniques and perform autocorrelation measurements at elevated excitation powers in confocal microscopy. Employing a three-level model allows us to extract the setup efficiency, individual transition rates and thus the internal quantum efficiency of our system. Combining our results, we find that the enhancement of the radiative decay rate via the Purcell effect results in an internal quantum efficiency of 90 % for cavity-coupled NV centers. Our findings will facilitate the realization of nano-scale single photon sources with near-unity internal quantum efficiencies operating at high repetition rates.
Engineering the photo-emission characteristics of single-photon emitters is crucial for the growing field of quantum technologies. We show that the photoluminescence of a single nitrogen-vacancy color center in nanodiamond could be significantly enhanced when attached to a gold film of 50 nm with preserving photophysical properties as a single photon source. The nitrogen-vacancy center on the gold film showed a decreased excited-state lifetime and a modified saturation characteristic. The photoluminescence enhancement was due to the enhanced electric field by the surface plasmon and the energy transfer from the excited state of nitrogen-vacancy centers to the surface plasmon.
Unlocking the quantum potential of nitrogen-vacancy (NV) centers in diamonds has led to innovative advancements in sensing applications. By coupling NV centers with plasmonic nanostructures, ultrasensitive biolabels are envisioned. To this end, we exploit DNA self-assembly to create hybrid plasmonic nanodiamonds, featuring a closed nanocavity encapsulating a single nanodiamond. Correlated spectroscopy reveals enhanced brightness and emission rates, crucial for quantum sensing. This synergy between plasmonics and diamond fluorescence augments photon emission intensity and accelerates emission rates, enabling improved temporal resolution. These nanodiamonds hold promise as stable single-photon sources and versatile platforms for probing quantum effects in biology. This talk highlights the development, properties, and potential applications of these nanodiamonds, bridging quantum sensing and biomedicine, and fostering transformative changes in biophotonics.
Artificially tailoring quantum emitters by coupling them to optical cavities is critical for applications such as all-photonic quantum computing and quantum key distribution. Among quantum emitters, diamond defect centers, with their atomic-like characteristics, have drawn intense interest for quantum applications. However, the spontaneous emission lifetime of single photons from diamond defects has been limited to several hundred picoseconds, partly due to challenges in realizing cavities in diamond with sufficiently small mode volumes. Here, we sandwich an only 10 nm diamond membrane with implanted negatively charged silicon vacancy centers (SiV – ) between a gold mirror and arrays of nanodisks, resulting in ultrafast single-photon sources with lifetimes as short as 5.5 ps. This corresponds to an improvement in the radiative spontaneous emission rate of over 700-fold, also termed the Purcell factor, and is the result of a greatly enhanced local density of states in the ultrasmall mode-volume cavities. Furthermore, the cavity-coupled single SiV – centers exhibit a 4800-fold photoluminescence enhancement with a single-photon generation rate of up to 361 Mcps at room temperature. These results could refine the engineering of diamond defect centers and position other solid-state platforms as strong quantum-information contenders when coupled to ultrasmall mode-volume cavities, thus illustrating the potential for large-scale, artificially tailored single-photon sources.