Multiplexed Readout of Transmon Qubits with Josephson Bifurcation Amplifiers

TL;DR

This paper demonstrates a scalable, high-fidelity multiplexed readout method for four transmon qubits using Josephson bifurcation amplifiers, enabling simultaneous measurement without requiring large bandwidth quantum-limited amplifiers.

Contribution

The authors implement and validate multiplexed qubit readout with Josephson bifurcation amplifiers, showing improved scalability over traditional linear resonator methods.

Findings

Successful simultaneous measurement of four transmon qubits.

Multiplexed Josephson bifurcation provides high-fidelity readout.

Scalability is not limited by bandwidth constraints.

Abstract

Achieving individual qubit readout is a major challenge in the development of scalable superconducting quantum processors. We have implemented the multiplexed readout of a four transmon qubit circuit using non-linear resonators operated as Josephson bifurcation amplifiers. We demonstrate the simultaneous measurement of Rabi oscillations of the four transmons. We find that multiplexed Josephson bifurcation is a high-fidelity readout method, the scalability of which is not limited by the need of a large bandwidth nearly quantum-limited amplifier as is the case with linear readout resonators.