  Nonlinear mean field dynamics enables quantum information processing
operations that are impossible in linear one-particle quantum mechanics. In
this approach, a register of bosonic qubits (such as neutral atoms or
polaritons) is initialized into a symmetric product state through condensation,
then subsequently controlled by varying the qubit-qubit interaction. We propose
an experimental implementation of quantum state discrimination, an important
subroutine in quantum computation, with a toroidal Bose-Einstein condensate.
The condensed bosons here are atoms, each in the same superposition of angular
momenta 0 and 1, encoding a qubit. A nice feature of the protocol is that only
readout of individual quantized circulation states (not superpositions) is
required.
