NEGATIVE ENTROPY AND INFORMATION IN QUANTUM-MECHANICS

A framework for a quantum mechanical information theory is introduced that is based entirely on density operators, and gives rise to a unifi ed description of classical correlation and quantum entanglement. Unli ke in classical (Shannon) information theory, quantum (von Neumann) co nditional entropies can be negative when considering quantum entangled systems, a fact related to quantum nonseparability. The possibility t hat negative (virtual) information can be carried by entangled particl es suggests a consistent interpretation of quantum informational proce sses. [S0031-9007(97)04813-8].