  We propose and demonstrate a technique for quantum random number generation
based on the random population of the output spatial modes of a beam splitter
when both inputs are simultaneously fed with indistinguishable weak coherent
states. We simulate and experimentally validate the probability of generation
of random bits as a function of the average photon number per input, and
compare it to the traditional approach of a single weak coherent state
transmitted through a beam-splitter, showing an improvement of up to 32\%. The
ensuing interference phenomenon reduces the probability of coincident counts
between the detectors associated with bits 0 and 1, thus increasing the
probability of occurrence of a valid output. A long bit string is assessed by a
standard randomness test suite with good confidence. Our proposal can be easily
implemented and opens attractive performance gains without a significant
trade-off.
