  Quantum memories are an integral component of quantum repeaters - devices
that will allow the extension of quantum key distribution to communication
ranges beyond that permissible by passive transmission. A quantum memory for
this application needs to be highly efficient and have coherence times
approaching a millisecond. Here we report on work towards this goal, with the
development of a $^{87}$Rb magneto-optical trap with a peak optical depth of
1000 for the D2 $F=2 \rightarrow F'=3$ transition using spatial and temporal
dark spots. With this purpose-built cold atomic ensemble to implement the
gradient echo memory (GEM) scheme. Our data shows a memory efficiency of $80\pm
2$% and coherence times up to 195 $\mu$s, which is a factor of four greater
than previous GEM experiments implemented in warm vapour cells.
