THE QUANTUM CAPACITY BOUNDS OF A LOSSY GAUSSIAN QUANTUM CHANNEL.

Quantum capacity of the lossy Gaussian quantum channel remains an open problem in quantum information theory, although the upper and lower bounds are well-known. We show that for the n-use of the channel, the input of entangled commutative Gaussian state does not improve the lower bound of the capacity. When the total energy is limited, an unfair distribution of the energy among the n-use will improve the lower bound. [ABSTRACT FROM AUTHOR]