EQuAL Seminar: Shreyas Pathasarathy

Engineering Novel Qubit Systems by Harnessing the Solid-state Environment

The nitrogen vacancy (NV) center is a spin qubit in diamond that is often thought of as an isolated atom-like defect due to a few remarkable properties: efficient spin initialization via optical pumping, relatively high fluorescence, and a rigid “vacuum-like” host lattice that can facilitate millisecond-long spin coherence times at room temperature. Its immense sensing utility comes from combining these atom-like properties with practical advantages of solid-state devices: nanoscale spatial resolution (due to confinement to single lattice sites) and strong coupling to fields of interest (due to device geometries that can minimize sensor-target separation). In this EQuAL seminar, I will describe how surmounting current limitations on NV-based sensors requires a more detailed microscopic understanding of the role of the solid-state environment. I will introduce our tools for understanding the plethora of interactions that we often lump together as “decoherence,” and discuss how that understanding can open up exciting new possibilities: interesting hybrid qubit architectures for quantum simulation and dense ensembles of sensors for interaction-assisted sensing schemes. The theme I will emphasize is that combining principles from areas spanning atomic and many-body physics, NMR/EPR, and materials science is a potentially rewarding path towards scaling spin systems without losing atomic-level control over their properties.