We demonstrate a hybrid on-chip photonics platform based on crystalline silicon resonators and waveguides patterned on top of silicon carbide. The devices were fabricated with membrane transfer followed by standard electron beam patterning procedures. The platform allows the integration of high quality silicon photonics with color centers in silicon carbide operating in the near infrared for spin-photon interfaces used in quantum information processing applications. We measure waveguide-coupled ring resonators with loaded quality factors up to 23 000 at cryogenic temperatures.

We present progress towards a bidirectional coherent microwave-to-optical photon converter using an ensemble of rare-earth ions coupled to integrated photonic and microwave resonators. © 2019 The Author(s)

Quantum interconnects allow disparate quantum systems to be entangled, leading to more powerful integrated quantum technology and increases in scalability. The foundation for such technology, including photonic quantum memories and coherent microwave-to-optical (M2O) transducers, have already been developed in rare-earth ion (REI) crystals. Here we demonstrate improved REI quantum device functionality in an on-chip platform that dramatically strengthens the ions’ interactions with optical fields and integrates with planar microwave technology. Using a photonic crystal nanobeam fabricated in a Nd-doped yttrium vanadate (YVO) crystal, we harness the enhanced ion-photon interactions that create single photon Rabi frequencies as large as 60 MHz. In particular, the large AC Stark shift is used to control an ensemble of approximately 4000 ions for photonic quantum memory applications. We demonstrate AC Stark shift control of the storage time in the atomic frequency comb protocol as well as the possibility of memories based on an all-optical variation of the hybrid photon echo rephasing protocol. The spin state of the REIs can also be addressed directly through the integration of microwave striplines and coplanar waveguide cavities. The achievement of optically detected magnetic resonance in on-chip waveguides and nanophotonic cavities in Nd:YVO will be presented along with the initial progress of achieving coherent M2O conversion using Raman heterodyne spectroscopy. With photonic quantum memories and sources, single ion qubits, and quantum M2O all feasible in the one integrated platform, REI technology is a promising platform for enabling large scale integration of diverse quantum resources.

We present hybrid crystalline-silicon (c-Si) ring resonators on top of 4H silicon carbide with measured quality factor ~9600 for coupling to spin qubits like divacancies and Cr ions for future applications in quantum information networks.