Properties of the (Un)Complexity of Subsystems

Abstract

I investigate some properties of proposed definitions for subsystem/mixed state complexity and uncomplexity. A very strong dependence arises on the density matrix's degeneracy which gives a large separation in the scaling of maximum subsystem complexity with number of qubits (linear compared to exponential). I also investigate several cases where the uncomplexity of quantum states are superadditive and present some challenges and progress in showing that the relation holds in complete generality.

7 pages, 3 figures V2: typos fixed and citations added