Optically addressable molecular spin qubits

Solid-state color centers are a promising platform for quantum technologies due to their combination of a ground-state spin which can be initialized and read out optically. However, their top-down architecture makes it challenging to atomistically control their properties. Chemically synthesized molecules provide an alternative bottom-up approach for optically addressable spin systems, offering an intrinsically tunable, scalable and host-agnostic architecture.
Here we realize optically addressable spin qubits in organometallic molecules. We demonstrate optical initialization and readout, and microwave coherent control of ground-state spins in chromium(IV)-based molecules [1]. We generate molecules with a spin-1 ground state that can be interfaced with light through spin-selective optical pumping, and manipulated with microwave fields. We show that minor chemical modifications alter the spin, optical and structural properties of these compounds, highlighting the atomistic tunability offered by a molecular qubit platform. Our results demonstrate the promise of molecular systems for quantum information science, and a route to scalable, portable and tunable qubit architectures.

[1] Bayliss*, Laorenza* et al., Science (in press), arXiv:2004.07998