  We present results for the binding energies for ^4He and ^3He nuclei
calculated in quenched lattice QCD at the lattice spacing of a =0.128 fm with a
heavy quark mass corresponding to m_pi = 0.8 GeV. Enormous computational cost
for the nucleus correlation functions is reduced by avoiding redundancy of
equivalent contractions stemming from permutation symmetry of protons or
neutrons in the nucleus and various other symmetries. To distinguish a bound
state from an attractive scattering state, we investigate the volume dependence
of the energy difference between the ground state energy of the nucleus channel
and the free multi-nucleon states by changing the spatial extent of the lattice
from 3.1 fm to 12.3 fm. A finite energy difference left in the infinite spatial
volume limit leads to the conclusion that the measured ground states are
bounded. It is also encouraging that the measured binding energies and the
experimental ones show the same order of magnitude.
