Modular chip-integrated photonic control of artificial atoms in diamond waveguides

A central goal in creating long-distance quantum networks and distributed quantum computing is the development of interconnected and individually controlled qubit nodes. Atom-like emitters in diamond have emerged as a leading system for optically networked quantum memories, motivating the development of visible-spectrum, multi-channel photonic integrated circuit (PIC) systems for scalable atom control. However, it has remained an open challenge to realize optical programmability with a qubit layer that can achieve high optical detection probability over many optical channels. Here, we address this problem by introducing a modular architecture of piezoelectrically actuated atom-control PICs (APICs) and artificial atoms embedded in diamond nanostructures designed for high-efficiency free-space collection. The high-speed four-channel APIC is based on a splitting tree mesh with triple-phase shifter Mach-Zehnder interferometers. This design simultaneously achieves optically broadband operation at visible wavelengths, high-fidelity switching (>40 dB) at low voltages, submicrosecond modulation timescales (>30 MHz), and minimal channel-to-channel crosstalk for repeatable optical pulse carving. Via a reconfigurable free- space interconnect, we use the APIC to address single silicon vacancy color centers in individual diamond waveguides with inverse tapered couplers, achieving efficient single photon detection probabilities (similar to 15%) and second-order autocorrelation measurements g((2))(0) < 0.14 for all channels. The modularity of this distributed APIC-quantum memory system simplifies the quantum control problem, potentially enabling further scaling to thousands of channels. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement