  Heralded spontaneous parametric down-conversion (SPDC) has become the
mainstay for single-photon state preparation in present-day photonics
experiments. Because they are heralded, in principle one knows when a single
photon has been prepared. However, the heralding efficiencies in experimentally
realistic SPDC sources are typically very low. To overcome this, multiplexing
techniques have been proposed which employ a bank of SPDC sources in parallel,
and route successfully heralded photons to the output, thereby effectively
boosting the heralding efficiency. However, running a large bank of independent
SPDC sources is costly and requires complex switching. We analyse a
multiplexing technique based on time-bin encoding that allows the heralding
efficiency of just a single SPDC source to be increased. The scheme is simple
and experimentally viable using present-day technology. We analyse the
operation of the scheme in terms of experimentally realistic considerations,
such as losses, detector inefficiency, and pump-power.
