  The superconductor-insulator transition (SIT) is an excellent example for a
quantum phase transition at zero temperature, dominated by quantum
fluctuations. These are expected to be very prominent close to the quantum
critical point. So far most of the experimental study of the SIT has
concentrated on transport properties and tunneling experiments which provide
indirect information on criticality close to the transition. Here we present an
experiment uniquely designed to study the evolution of quantum fluctuations
through the quantum critical point. We utilize the Nernst effect, which has
been shown to be effective in probing superconducting fluctuation. We measure
the Nernst coefficient in amorphous indium oxide films tuned through the SIT
and find a large signal on both the superconducting and the insulating sides
which peaks close to the critical point. The transverse Peltier coefficient,
$\alpha_{xy}$ which is the thermodynamic quantity extracted from these
measurements, follows quantum critical scaling with critical exponents $\nu
\sim 0.7$ and $z \sim 1$ which is consistent with a clean XY model in 2+1
dimensions.
