  We show that a large entangled current can be produced from a very simple
passive device: a cluster of three resonant quantum dots, tunnel coupled to one
input lead and two output leads. The device can function in a `clean' mode,
when almost all emitted electrons are paired in Bell states, or a `dirty' mode
with a far higher emission rate but a significant portion of non-entangled
electrons. Subsequent charge detection can enhance performance by identifying
the pairs that are most likely to be entangled. The device is robust to
specific choice of system parameters and therefore lends itself to immediate
experimental demonstration. Applications include quantum repeaters and
unconditionally secure interfaces.
