  We propose a new way of implementing several elementary quantum gates for
qubits in the coherent state basis. The operations are probabilistic and employ
single photon subtractions as the driving force. Our schemes for single-qubit
phase gate and two-qubit controlled phase gate are capable of achieving
arbitrarily large phase shifts with currently available resources, which makes
them suitable for the near-future tests of quantum information processing with
superposed coherent states.
