Readout for phase qubits without Josephson junctions
Matthias Steffen, Shwetank Kumar, David Peter Divincenzo, George Keefe, M. B. Ketchen, Mary Beth Rothwell, Jim Rozen · Applied Physics Letters · 2010
We present a readout scheme for phase qubits which eliminates the read-out superconducting quantum interference device so that the entire qubit and measurement circuitry only require a single Josephson junction. Our scheme capacitively couples the phase qubit directly to a transmission line and detects its state after the measurement pulse by determining a frequency shift observable in the forward scattering parameter of the readout microwaves. This readout is extendable to multiple phase qubits coupled to a common readout line and can in principle be used for other flux biased qubits having two quasistable readout configurations.