Quantum Measurements with Superconducting Circuits
Tanay Roy, A. M. Vadiraj, Madhavi Chand, Arpit Ranadive, Suman Kundu, Meghan P. Patankar, Rajamani Vijay · Current Science · 2015
We measure the state of a superconducting quantum bit (qubit) coupled to a microwave cavity by scattering a microwave signal from the cavity. The scattered signal is amplified using a low-noise Josephson parametric amplifier. We carried out measurements to infer the coherence properties of the qubit. In the strong measurement regime, we observe quantum jumps between the qubit states in real time, while we observe stochastic quantum trajectories in the weak measurement regime. The coherence times and measurement fidelity obtained are sufficient for implementing quantum error correction.