Quantum Darwinism in a Mixed Environment
Abstract
Quantum Darwinism recognizes that we—the observers—acquire our information about the “systems of interest” indirectly from their imprints on the environment. Here, we show that information about a system can be acquired from a mixedstate, or hazy, environment, but the storage capacity of an environment fragment is suppressed by its initial entropy. In the case of good decoherence, the mutual information between the system and the fragment is given solely by the fragment’s entropy increase. For fairly mixed environments, this means a reduction by a factor 1h, where h is the haziness of the environment, i.e., the initial entropy of an environment qubit. Thus, even such hazy environments eventually reveal the state of the system, although now the intercepted environment fragment must be larger by ∼(1h)^{1} to gain the same information about the system.
 Publication:

Physical Review Letters
 Pub Date:
 September 2009
 DOI:
 10.1103/PhysRevLett.103.110402
 arXiv:
 arXiv:0904.0418
 Bibcode:
 2009PhRvL.103k0402Z
 Keywords:

 03.65.Ta;
 03.65.Yz;
 Foundations of quantum mechanics;
 measurement theory;
 Decoherence;
 open systems;
 quantum statistical methods;
 Quantum Physics
 EPrint:
 4 pages, 3 figures