Quantum Abacus
  We show that the U(2) family of point interactions on a line can be utilized to provide the U(2) family of qubit operations for quantum information processing. Qubits are realized as localized states in either side of the point interaction which represents a controllable gate. The manipulation of qubits proceeds in a manner analogous to the operation of an abacus.   Keywords: quantum computation, quantum contact interaction, quantum wire 
Taksu Cheon (Kochi Tech), Izumi Tsutsui (KEK), Tamas Fulop (KEK)