  In this paper, we propose a novel quantum multiple access technique based on
optical coherent states. The information of several coherent state optical
qubits is combined into a single qudit, which is the superposition of almost
orthogonal coherent states. The original information is encoded into a new
Hilbert space with the help of a quantum multiplexer (QMUX) and then recovered
at the other end with a quantum demultiplexer (QDEMUX). We introduce the
optical tools that complete the coherence state quantum computation model and
give the desired circuits. The proposed system can admit a number of users
above the optimal limit at the cost of a degradation of the transmitted data.
In this and some other aspects, it can be regarded as a quantum analogue of
classical Code Division Multiple Access techniques.
