Observation of the Transition from Reversible to Irreversible Decoherence of Mesoscopic Quantum Superpositions
The study used circuit QED to test how unitary evolution causes irreversible decoherence in quantum systems. By coupling a photonic cat state to eight nonlinear electronic oscillators (the reservoir), researchers found that increasing the number of coupled qubits makes the loss of quantum coherence permanent. This happens because the information about which path the system took becomes irreversibly spread across many degrees of freedom.