  It has recently been shown theoretically that elastic scattering in the Fermi
sea produces quantum mechanically entangled states. The mechanism is similar to
entanglement by a beam splitter in optics, but a key distinction is that the
electronic mechanism works even if the source is in local thermal equilibrium.
An experimental realization was proposed using tunneling between two edge
channels in a strong magnetic field. Here we investigate a low-magnetic field
alternative, using multiple scattering in a quantum dot. Two pairs of
single-channel point contacts define a pair of qubits. If the scattering is
chaotic, a universal statistical description of the entanglement production
(quantified by the concurrence) is possible. The mean concurrence turns out to
be almost independent on whether time-reversal symmetry is broken or not. We
show how the concurrence can be extracted from a Bell inequality using
low-frequency noise measurements, without requiring the tunneling assumption of
earlier work.
