  We present a novel approach to transient Raman spectroscopy, which combines
stochastic probe pulses and a covariance-based detection to measure stimulated
Raman signals in alpha-quartz. A coherent broadband pump is used to
simultaneously impulsively excite a range of different phonon modes, and the
phase, amplitude, and energy of each mode are independently recovered as a
function of the pump-probe delay by a noisy-probe and covariance-based
analysis. Our experimental results and the associated theoretical description
demonstrate the feasibility of 2D-Raman experiments based on the stochastic
probe schemes, with new capabilities not available in equivalent
mean-value-based 2D-Raman techniques. This work unlocks the gate for nonlinear
spectroscopies to capitalize on the information hidden within the noise and
overlooked by a mean-value analysis.
