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Register a new userOvercoming the rate-directionality tradeoff: a room-temperature ultrabright quantum light source
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Deterministic GHz-rate single photon sources at room-temperature would be essential components for various quantum applications. However, both the slow intrinsic decay rate and the omnidirectional emission of typical quantum emitters are two obstacles towards achieving such a goal which are hard to overcome simultaneously. Here we solve this challenge by a hybrid approach, using a complex monolithic photonic resonator constructed of a gold nanocone responsible for the rate enhancement, and a circular Bragg antenna for emission directionality. A repeatable process accurately binds quantum dots to the tip of the antenna-embedded nanocone. As a result we achieve simultaneous 20-fold emission rate enhancement and record-high directionality leading to an increase in the observed brightness by a factor as large as 580 (120) into an NA = 0.22 (0.5). We project that such miniaturized on-chip devices can reach photon rates approaching 2.3*10^8 single photons/second thus enabling ultra-fast light-matter interfaces for quantum technologies at ambient conditions.
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We demonstrate dispersive readout of the spin of an ensemble of Nitrogen-Vacancy centers in a high-quality dielectric microwave resonator at room temperature. The spin state is inferred from the reflection phase of a microwave signal probing the resonator. Time-dependent tracking of the spin state is demonstrated, and is employed to measure the T1 relaxation time of the spin ensemble. Dispersive readout provides a microwave interface to solid state spins, translating a spin signal into a microwave phase shift. We estimate that its sensitivity can outperform optical readout schemes, owing to the high accuracy achievable in a measurement of phase. The scheme is moreover applicable to optically inactive spin defects and it is non-destructive, which renders it insensitive to several systematic errors of optical readout and enables the use of quantum feedback.
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