Interaction-enhanced quantum sensing at infinite temperature

Precision beyond the standard quantum limit, a central goal of modern quantum metrology, is commonly achieved by preparing entangled pure states with highly structured quantum correlations. In this talk, I will introduce sensing protocols in which a scalable metrological advantage arises instead from unentangled states at infinite temperature, enabled by time-reversing the interactions within the sensor. I will discuss two applications: nanoscale magnetometry using the scrambling dynamics of optically dark spins in diamond, and molecular spectroscopy using nuclear magnetic resonance in the zero-to-ultralow-field (ZULF) regime.