Nuclear Numerical Range and Quantum Error Correction Codes for non-unitary noise models
arXiv:1610.00930 · doi:10.1007/s11128-016-1484-8
Abstract
We introduce a notion of nuclear numerical range defined as the set of expectation values of a given operator among normalized pure states, which belong to the nucleus of an auxiliary operator . This notion proves to be applicable to investigate models of quantum noise with block-diagonal structure of the corresponding Kraus operators. The problem of constructing a suitable quantum error correction code for this model can be restated as a geometric problem of finding intersection points of certain sets in the complex plane. This technique, worked out in the case of two-qubit systems, can be generalized for larger dimensions.
22 pages, 3 figures