Multiplexed readout of four qubits in 3D circuit QED architecture using a broadband Josephson parametric amplifier
S. Kundu, Nicolas Gheeraert, Sumeru Hazra, Tanay Roy, Kishor V. Salunkhe, Meghan P. Patankar, Rajamani Vijay · Applied Physics Letters · 2019
We propose and demonstrate a frequency-multiplexed readout scheme in 3D circuit-quantum electrodynamics (cQED) architecture. We use four transmon qubits coupled to individual rectangular cavities which are aperture-coupled to a common rectangular waveguide feedline. A coaxial to waveguide transformer at the other end of the feedline allows one to launch and collect the multiplexed signal. The reflected readout signal is amplified by an impedance-engineered broadband parametric amplifier with 380 MHz bandwidth. This provides us high fidelity single-shot readout of multiple qubits using compact microwave circuitry, an efficient way for scaling up to more qubits in 3D cQED.