Waveguide-integrated colour centres in silicon carbide with broadband photonic crystal reflectors for efficient readout

TL;DR

This paper demonstrates the design and fabrication of waveguide-integrated silicon carbide colour centres with broadband photonic crystal reflectors, achieving high photon count rates and enabling efficient optical single-shot readout for quantum information applications.

Contribution

It introduces a novel waveguide structure with broadband reflectors for silicon carbide colour centres, enhancing photon collection and readout efficiency at cryogenic temperatures.

Findings

Broadband reflection over 60 THz with >80% peak reflectance.

Achieved photon count rates up to 125 kcps.

Theoretical analysis shows >98% fidelity for single-shot readout.

Abstract

Spin-active colour centres in 4H silicon carbide are promising candidates as building blocks for quantum information applications. To increase the photon count rate of the emitters at low temperatures, the colour centres must be integrated into nanophotonic structures and characterised under cryogenic conditions. Here, we design and fabricate waveguide structures attached with an efficient Dinosaur photonic crystal reflector at one side. The devices show broadband reflection over a range of 60 THz with a peak reflectance above 80 %. Additionally, colour centres were integrated into these structures and characterised at cryogenic conditions. The emission was collected by a tapered-waveguide-tapered-fibre interface. Although the spectral stability of the emitters must be further improved for high excitation powers, the saturation intensity in standard PLE measurements is about 104 kcps. The count rate can be further improved to about 125 kcps with a charge-resonance check measurement scheme. To highlight the relevance of our devices, we theoretically show that these count rates enable optical single-shot readout with a fidelity exceeding 98 %.