Indeterminate-length quantum coding
  The quantum analogues of classical variable-length codes are indeterminate-length quantum codes, in which codewords may exist in superpositions of different lengths. This paper explores some of their properties. The length observable for such codes is governed by a quantum version of the Kraft-McMillan inequality. Indeterminate-length quantum codes also provide an alternate approach to quantum data compression. 
Benjamin Schumacher (Kenyon College) and Michael D. Westmoreland   (Denison University)