Lower Bounds for Learning Quantum States with Single-Copy Measurements

Understand

We study the problems of quantum tomography and shadow tomography using measurements performed on individual, identical copies of an unknown $d$-dimensional state.

• We first revisit a known lower bound due to Haah et al.
• (2017) on quantum tomography with accuracy $\epsilon$ in trace distance, when the measurements choices are independent of previously observed outcomes (i.e., they are nonadaptive).
• We give a succinct proof of this result.