Joint measurability through Naimark's theorem

Abstract

We use Naimark's dilation theorem in order to characterize the joint measurability of two POVMs. Then, we analyze the joint measurability of two commutative POVMs $F_1$ and $F_2$ which are the smearing of two self-adjoint operators $A_1$ and $A_2$ respectively. We prove that the compatibility of $F_1$ and $F_2$ is connected to the existence of two compatible self-adjoint dilations $A_1^{+}$ and $A_2^{+}$ of $A_1$ and $A_2$ respectively. As a corollary we prove that each couple of self-adjoint operators can be dilated to a couple of compatible self-adjoint operators. Next, we analyze the joint measurability of the unsharp position and momentum observables and show that it provides a master example of the scheme we propose. Finally, we give a sufficient condition for the compatibility of two effects.

References in corpus (5)

• Classical Representations of Quantum Mechanics Related to Statistically Complete Observables
• On coexistence and joint measurability of rank-1 quantum observables
• Quantum theory realises all joint measurability graphs
• Compatibility for Probabilistic Theories
• Semispectral Measures and Feller markov Kernels

Cited by in corpus (1)

• POVMs and the Two Theorems of Naimark and Sz.-Nagy