  We derive an effective field theory for the isotropic-nematic quantum phase
transition of fractional quantum Hall (FQH) states. We demonstrate that for a
system with an isotropic background the low-energy effective theory of the
nematic order parameter has $z=2$ dynamical scaling exponent, due to a Berry
phase term of the order parameter, which is related to the non-dissipative Hall
viscosity. Employing the composite fermion theory with a quadrupolar
interaction between electrons, we show that a sufficiently attractive
quadrupolar interaction triggers a phase transition from the isotropic FQH
fluid into a nematic fractional quantum Hall phase. By investigating the
spectrum of collective excitations, we demonstrate that the mass gap of
Girvin-MacDonald-Platzman (GMP) mode collapses at the isotropic-nematic quantum
phase transition. On the other hand, Laughlin quasiparticles and the Kohn
collective mode remain gapped at this quantum phase transition, and Kohn's
theorem is satisfied. The leading couplings between the nematic order parameter
and the gauge fields include a term of the same form as Wen-Zee term. A
disclination of the nematic order parameter carries an unquantized electric
charge. We also discuss the relation between nematic degrees of freedom and the
geometrical response of the fractional quantum Hall fluid.
