Quantum entropy-typical subspace and universal data compression
  The quantum entropy-typical subspace theory is specified. It is shown that any mixed state with von Neumann entropy less than h can be preserved approximately by the entropy-typical subspace with entropy= h. This result implies an universal compression scheme for the case that the von Neumann entropy of the source does not exceed h. 
Jingliang Gao and Yanbo Yang
quant-ph cs.IT math.IT