Single photon emission and single spin coherence of a nitrogen vacancy center encapsulated in silicon nitride

Abstract

Finding the right material platform for engineering efficient photonic interfaces to solid state emitters has been a long-standing bottleneck for scaling up solid state quantum systems. In this work, we demonstrate that nitrogen-rich silicon nitride, with its low background auto-fluorescence at visible wavelengths, is a viable quantum photonics platform by showing that nitrogen vacancy centres embedded in nanodiamonds preserve both their quantum optical and spin properties post-encapsulation. Given the variety of high-performance photonic components already demonstrated in silicon nitride, our work opens up a new avenue for building integrated photonic circuits using solid state emitters. arXiv:1909.09383v1 [physics.app-ph] Keywords Colour centre, nanodiamond, silicon nitride, integrated quantum photonics, solid state quantum emitters, atom-like systems

Room-temperature single-photon emitters in silicon nitride

“…However, commonly used stoichiometric Si 3 N 4 has relatively strong background emission in the visible range that hinders quantum measurements, particularly regarding SPEs operating in this spectral region ( 33 ). To make SiN practical for quantum photonic applications in the visible range, nonstoichiometric nitrogen-rich SiN films with low background emission were explored ( 35 , 36 ). It was shown that nitrogen-rich SiN films grown by plasma-enhanced chemical vapor deposition (PECVD) have substantially lower autofluorescence compared to stoichiometric Si 3 N 4 while maintaining a moderate refractive index of ~1.9, suitable for quantum photonic measurements of encapsulated nitrogen vacancy centers ( 36 ).…”

The NV centre coupled to an ultra-small mode volume cavity: a high efficiency source of indistinguishable photons at 200 K

“…These 'bow tie' cavities would show extremely high spontaneous emission enhancements at reasonably low quality factors suitable for enhancing broader ZPL modes. Here, we demonstrate such a cavity design in silicon nitride, compatible with our demonstration of low fluorescence silicon nitride films encapsulating nanodiamond containing single NV centres 9 . With an ultra-small (<< λ 3 ) mode volume, it is possible to achieve a large atom-cavity coupling rate g, which serves to increase the Purcell-enhanced spontaneous emission rate R ∼ g 2 /κ c , where κ c is the cavity linewidth (or leakage rate).…”

“…In this work aimed at NV centres we have developed a planar nanodiamond-silicon nitride cavity design considering robustness to the Q factor and the NV centre position. Following our recent work encapsulating NV centres in silicon nitride 9 , it should be possible to fabricate this design as a step towards on-demand indistinguishable photons above cryogenic temperatures.…”

Silicon Nitride Waveguides with Intrinsic Single-Photon Emitters for Integrated Quantum Photonics

“…Ellipsometry characterization of the samples revealed that the refractive index n of the resultant SiN films was ∼1.7. This value is lower than the typical refractive index of n = 2.0 reported for stoichiometric Si 3 N 4 due to the need for low-autofluorescence SiN. , The waveguides were designed and simulated using a commercial Maxwell solver. We simulated the coupling efficiency β given by the ratio of the light intensity coupled to the fundamental mode of the waveguide to the total emitted light intensity from the dipole.…”

“…While stoichiometric Si 3 N 4 provides ultra-low loss photonic waveguides, the non-stoichiometric nitrogen-rich SiN used in our work offers substantially lower background fluorescence in the visible spectral range. This facilitates the integration with visible-wavelength quantum emitters. , In this work, we demonstrate individually addressable intrinsic single-photon sources in SiN photonic structures. To accomplish this, we grew low-autofluorescence SiN films with bright, stable, room-temperature quantum emitters on SiO 2 -coated silicon substrates.…”