We have numerically investigated the doped t-J ladder using exact
diagonalization. We have studied both the limit of strong inter-chain coupling
and isotropic coupling. The ladder scales to the Luther-Emery liquid regime in
the strong inter-chain coupling limit. In this strong coupling limit there is a
simple picture of the excitation spectrum that can be continued to explain the
behavior at isotropic coupling. At J=0 we have indications of a ferromagnetic
ground state. At a large J/t the ladder is phase separated into holes and a
Heisenberg ladder. At intermediate coupling the ground state shows hole pairing
with a modified d-wave symmetry. The excitation spectrum separates into a
limited number of quasiparticles which carry charge +∣e∣ and spin 21​ and a triplet magnon mode. At half-filling the former vanish but the latter
evolves continuously into the magnon band of the spin liquid. At low doping the
quasiparticles form a dilute Fermi gas with a strong attraction but
simultaneously the Fermi wave vector, as would be measured in photoemission, is
large. The dynamical structure factors are calculated and are found to be very
similar to calculations on 2D clusters