Multiplexed Readout of Four Qubits in 3D cQED Architecture Using Broadband JPA

We propose and demonstrate a frequency-multiplexed readout scheme in 3D 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 of 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. I conclude the talk by discussing some latest results on a new type of qubit-cavity system measured using a 3D waveguide.

In Collaboration with:
Suman Kundu, Nicolas Gheeraert, Sumeru Hazra, Tanay Roy*, Kishor V. Salunkhe, Meghan P. Patankar.

Affiliation: Tata Institute of Fundamental Research, Mumbai
*Present affiliation: Department of Physics and James Franck Institute, University of Chicago