The conductivity and Hall coefficient for various types of t-J ladders are calculated as a function of temperature and frequency by numerical diagonalization. A crossover from incoherent to coherent charge dynamics is found at a temperature Tcoh. There exists another crossover at TPG below which a pseudogap opens in the optical spectra, induced by the opening of a spin gap. In the absence of the spin gap, Tcoh and the coherent weight are suppressed especially with increasing dimensionality. On the contrary, Tcoh is strongly enhanced by the pseudogap formation below TPG, whereas the coherent Drude weight decreases with increasing dimensionality. The Hall coefficient shows a strong crossover at TPG below which it has large amplitude for small doping concentration.
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