  Brillouin microscopy is an emerging label-free imaging technique to assess
local viscoelastic properties. Quantum-enhanced stimulated Brillouin scattering
is demonstrated for the first time using low power continuous-wave lasers at
795~nm. A signal to noise ratio enhancement of 3.4~dB is reported by using
two-mode intensity-difference squeezed light generated with the four-wave
mixing process in atomic rubidium vapor. The low optical power and the
excitation wavelengths in the water transparency window has the potential to
provide a powerful bio-imaging technique for probing mechanical properties of
biological samples prone to phototoxicity and thermal effects. The performance
enhancement affordable through the use of quantum light may pave the way for
significantly improved sensitivity that cannot be achieved classically. The
proposed new way of utilizing squeezed light for enhanced stimulated Brillouin
scattering can be easily adapted for both spectroscopic and imaging
applications in materials science and biology.
