Cavity QED Based on Collective Magnetic Dipole Coupling: Spin Ensembles as Hybrid Two-Level Systems

Abstract

We analyze the magnetic dipole coupling of an ensemble of spins to a superconducting microwave stripline structure, incorporating a Josephson junction based transmon qubit. We show that this system is described by an embedded Jaynes-Cummings model: in the strong coupling regime, collective spin-wave excitations of the ensemble of electrons pick up the nonlinearity of the cavity mode, such that the two lowest eigenstates of the coupled spin-wave + microwave-cavity + Josephson-junction system define a hybrid two-level system. The proposal described here enables the use of spin ensembles as qubits which can be coherently manipulated and coupled using the same nonlinear-cavity. Possibility of strong-coupling cavity-QED with magnetic-dipole transitions opens up the possibility of extending previously proposed quantum information processing protocols to spins in silicon or graphene, without the need for single-electron confinement.

Locations

• Physical Review Letters - View
• arXiv (Cornell University) - View - PDF
• PubMed - View
• DataCite API - View