A feasible setup of continuous-variable (CV) quantum non-demolishing (QND)
interaction at a distance is proposed. If two distant experimentalists are able
to locally perform identical QND interactions then the proposed realization
requires only a single quantum channel and classical communication between
them. A possible implementation of the proposed setup in recent quantum optical
laboratories is discussed and an influence of Gaussian noise in the quantum
channel on a quality of the implementation is analyzed. An efficient
realization of the QND interaction at a distance can be a basic step to
possible distributed quantum CV experiments between the distant laboratories.Comment: 5 pages, 2 figure