Observation of measurement-induced entanglement and quantum trajectories of remote superconducting qubits

Understand

The creation of a quantum network requires the distribution of coherent information across macroscopic distances.

• We demonstrate the entanglement of two superconducting qubits, separated by more than a meter of coaxial cable, by designing a joint measurement that probabilistically projects onto an entangled state.
• By using a continuous measurement scheme, we are further able to observe single quantum trajectories of the joint two-qubit state, confirming the validity of the quantum Bayesian formalism for a cascaded system.
• Our results allow us to resolve the dynamics of continuous projection onto the entangled manifold, in quantitative agreement with theory.