  N = 6 superconformal Chern-Simons theory was proposed as gauge theory dual to
Type IIA string theory on AdS4*CP3. We study integrability of the theory from
conformal dimension spectrum of single trace operators at planar limit. At
strong `t Hooft coupling, the spectrum is obtained from excitation energy of
free superstring on OSp(6|2,2)/SO(3,1)xSU(3)xU(1) supercoset. We recall that
the worldsheet theory is integrable classically by utilizing well-known results
concerning sigma model on symmetric space. With R-symmetry group SU(4), we also
solve relevant Yang-Baxter equation for a spin chain system associated with the
single trace operators. From the solution, we construct alternating spin chain
Hamiltonian involving three-site interactions between 4 and 4*. At weak `t
Hooft coupling, we study gauge theory perturbatively, and calculate action of
dilatation operator to single trace operators up to two loops. To ensure
consistency, we computed all relevant Feynman diagrams contributing to the
dilatation opeator. We find that resulting spin chain Hamiltonian matches with
the Hamiltonian derived from Yang-Baxter equation. We further study new issues
arising from the shortest gauge invariant operators transforming as 15 and 1
under SU(4). We observe that `wrapping interactions' are present, compute the
true spectrum and find that the spectrum agrees with prediction from
supersymmetry. We also find that scaling dimension computed naively from
alternating spin chain Hamiltonian coincides with the true spectrum. We solve
Bethe ansatz equations for small number of excitations, and find indications of
correlation between excitations of 4's and 4*'s and of nonexistence of mesonic
(4 4*) bound-state.
