Heterogeneous Integration of Solid-State Quantum Systems with a Foundry Photonics Platform

Abstract

Diamond color centers are promising optically addressable solid-state spins that can be matter-qubits, mediate deterministic interaction between photons, and act as single photon emitters. Useful quantum computers will comprise millions of logical qubits. To become useful in constructing quantum computers, spin-photon interfaces must, therefore, become scalable and be compatible with mass-manufacturable photonics and electronics. Here, we demonstrate the heterogeneous integration of NV centers in nanodiamond with low-fluorescence silicon nitride photonics from a standard 180 nm CMOS foundry process. Nanodiamonds are positioned over predefined sites in a regular array on a waveguide in a single postprocessing step. Using an array of optical fibers, we excite NV centers selectively from an array of six integrated nanodiamond sites and collect the photoluminescence (PL) in each case into waveguide circuitry on-chip. We verify single photon emission by an on-chip Hanbury Brown and Twiss cross-correlation measurement, which is a key characterization experiment otherwise typically performed routinely with discrete optics. Our work opens up a simple and effective route to simultaneously address large arrays of individual optically active spins at scale, without requiring discrete bulk optical setups. This is enabled by the heterogeneous integration of NV center nanodiamonds with CMOS photonics.

Controlling All Degrees of Freedom of the Optical Coupling in Hybrid Quantum Photonics

“…In a final step, referred to as quantum post-processing (QPP), both entities are connected by means of optical coupling. Importantly, high-throughput integration processes are being developed to enable large-scale hybrid quantum photonic devices with simultaneous, multichannel access, and heterogeneous integration based on, for example, standard CMOS foundry processes . Further improvements arise from interaction zones, which are introduced in the photonics material prior to the QPP. , Nevertheless, QPP relies on high-precision yet typically statistical processes which do not enable optimization of the coupling strength.…”