Characterising a solid state qubit via environmental noise RalphJ.F. ClarkT.D. EverittMark PranceH. StiffellR.P. PranceR.J. 2013 We propose a method for characterising the energy level structure of a solid state qubit by monitoring the noise level in its environment. We consider a model persistent current qubit in a lossy reservoir and demonstrate that the noise in a classical bias field is a sensitive function of the applied field.