  A basic feasible probabilistic purification of unknown noisy coherent states,
outgoing from different state preparations with unknown mean number of thermal
photons, is proposed. The scheme is based only on a linear-optical network with
an avalanche photo-diode or heterodyne (homodyne) detection used to post-select
a successful processing. The suggested probabilistic method can produce an
output state with a lower noise than both quantum deterministic and classical
probabilistic distillation method. The purification applied in the state
preparation can increase classical capacity of communication and security of
quantum key distribution.
