Backaction-free measurement of quantum correlations via quantum time-domain interferometry

Understand

Time-domain interferometry (TDI) is a method to probe space-time correlations among particles in condensed matter systems.

• Applying TDI to quantum systems raises the general question, whether two-time correlations can be reliably measured without adverse impact of the measurement backaction onto the dynamics of the system.
• Here, we show that a recently developed quantum version of TDI (QTDI) indeed can access the full quantum-mechanical two-time correlations without backaction.
• We further generalize QTDI to weak classical continuous-mode coherent input states, alleviating the need for single-photon input fields.