  We have found a new hidden symmetry of time reversal light-atom interaction
in the photon echo quantum memory with Raman atomic transition. The
time-reversed quantum memory creates generalized conditions for ideal
compression/decompression of time duration of the input light pulses and its
wavelength. Based on a general analytical approach to this scheme, we have
studied the optimal conditions for the light field compression/decompression in
resonant atomic systems characterized by realistic spectral properties.
  The demonstrated necessary conditions for the effective quantum conversion of
the light waveform and wavelength are also discussed for various possible
realizations of the quantum memory scheme. The performed study promises new
capabilities for fundamental study of the light-atom interaction and
deterministic quantum manipulation of the light field, significant for quantum
communication and quantum computing.
