Method for Generating Randomly Perturbed Density Operators Subject to
  Different Sets of Constraints
This paper presents a general method for producing randomly perturbed density
operators subject to different sets of constraints. The perturbed density
operators are a specified "distance" away from the state described by the
original density operator. This approach is applied to a bipartite system of
qubits and used to examine the sensitivity of various entanglement measures on
the perturbation magnitude. The constraint sets used include constant energy,
constant entropy, and both constant energy and entropy. The method is then
applied to produce perturbed random quantum states that correspond with those
obtained experimentally for Bell states on the IBM quantum device ibmq_manila.
The results show that the methodology can be used to simulate the outcome of
real quantum devices where noise, which is important both in theory and
simulation, is present.
J. A. Montanez-Barrera R. T. Holladay G. P. Beretta Michael R. von Spakovsky