Circuit modelling of coupling between nanosystems and microwave coplanar waveguides

摘要

Exploiting the coupling between microwave waveguides and nanosystems is emerging as a new, powerful method of probing nanoscale devices. Such 'on-chip spectroscopy' was already demonstrated on superconducting quantum circuits (qubits) and nanoscale magnets. In this paper, we present an equivalent-circuit approach for the simulation and design of the coupled system. The waveguide structure is modelled by finite-element method and a 'modes to nodes' conversion yields to the circuit representation of the electromagnetic field problem. The nanosystem dynamics is modelled by equivalent circuits which are derived from the Landau-Lifshitz equations for nanomagnetic systems and by the Bloch equations for simple two-state quantum-mechanical problems. Interconnection of the two 'circuit modules' gives the model of the entire measurement set-up in a semiclassical approximation. Such 'field coupling' between nanosystems and microwave resonators can provide a novel, practical way for accessing nanoelectronic information processing devices.