Construction and classification of all equioverlapping measurements in qubit and qutrit systems
Zhihua Guo, Yan Liu, Tsung-Lin Lee, Shunlong Luo · Physical Review A · 2025
The overlap between quantum measurement operators is a fundamental quantity, and the notion of an equioverlapping measurement captures a symmetric feature of quantum measurements in terms of overlap. Such equioverlapping measurements, as a special class of quantum measurements, interpolate between von Neumann measurements and symmetric informationally complete positive operator-valued measures (SIC-POVMs), and exhibit a rich and subtle structure. In this work, we classify and completely determine all equioverlapping measurements in qubit and qutrit systems.