Quantum-enhanced sensing of molecular excited-state dynamics with correlated photons.

Quantum-correlated squeezed photons enable time-energy-resolved sensing of molecular excited-state dynamics, surpassing classical methods with enhanced selectivity and signal intensity.

• Why it matters: Understanding molecular excited-state dynamics is crucial for advancing photocatalysis and optoelectronics, but current classical pump-probe schemes lack the resolution and selectivity needed for detailed insights.
• What they did: A microscopic theory was developed to analyze a pump-probe scheme using spectrally tailored squeezed photons, demonstrating the ability to access molecular correlation functions and suppress ground-state signals.
• The result: The approach allows real-time monitoring of valley excitons and their conversion in a monolayer semiconductor, and shows that intermediate squeezing regimes favor time-resolved spectroscopy, enabling studies of nonequilibrium matter dynamics.