Agarwal is a leading quantum-optics theorist whose recent work (with Yakovlev) established quantum-enhanced stimulated Brillouin scattering spectroscopy and imaging, plus fundamental limits of quantum-enhanced sensing, entanglement-assisted spectroscopy and super-resolution. In the broader landscape of NV-centre ensemble quantum sensing (DEER, nano-NMR, T1 relaxometry) operating near pT/sqrt(Hz) sensitivity, this work supplies the estimation-theory backbone for beating classical sensitivity limits.