Optimally Weighted Constrained Shadow Tomography for Reduced Density Matrices

arXiv:2611.01079v1 Announce Type: new Abstract: Accurate measurement of reduced density matrices (RDMs) is central to quantum simulations of many-fermion systems, but the required measurement resources remain a significant challenge. Constrained shadow tomography (CST) combines randomized measurements with $N$-representability conditions to reconstruct physically valid RDMs from limited measurement data. Here we improve CST by orthogonalizing the measurement constraints and using the resulting singular values to determine the relative weight of each independent measurement direction according to how strongly it is sampled by the quantum computer.