CMT Seminar: Vanita Srinivasa

Enhanced-Range Entangling Mechanisms for Electron Spin Qubits

Many proposed realizations of quantum information processing rely on rapid and robust entanglement of coherent qubits over a wide range of distances. While solid-state implementations based on electron spin qubits are potentially scalable, spin manipulation and coupling methods that take advantage of rapid control of the electron charge are often limited in range and also remain susceptible to charge noise and relaxation. I will describe our theoretical approaches to addressing these challenges for spin qubits encoded in both single and multiple electrons within coupled quantum dots and hybrid atomic impurity-dot systems.

We find that a two-electron quantum dot mediates a tunable exchange interaction between spatially separated single-electron impurity spin qubits that yields high theoretical fidelities for entangling gates within silicon-based implementations in the presence of charge noise. We also show that the three-electron resonant exchange qubit combines a protected operating point for rapid single-qubit manipulation with an electric dipole moment that enables multiple approaches for long-range entangling gates via a superconducting microwave resonator. These methods are inspired by techniques from circuit quantum electrodynamics, Hartmann-Hahn double resonance in NMR, and the Cirac-Zoller gate for trapped ions.