Information-Theoretic Analysis of Weak Measurements and Their Reversal
Provides an information-theoretic characterization of weak measurement dynamics, relevant for quantum information and measurement theory.
The paper analyzes trade-offs in information extraction from quantum systems under null-result weak measurements, quantifying information accumulation over time via Shannon entropy, mutual information, fidelity, and relative entropy for qubit and qutrit systems.
We study trade-off relations in information extraction from quantum systems subject to null-result weak measurements, where the absence of a detected photon continuously updates the system state. We present a detailed analysis of qubit and qutrit systems and investigate a general framework for a multilevel quantum system. We develop a dynamical characterization of null-result weak measurements that quantifies the information extracted over time, revealing the amount of the obtained information and also the rate of the information accumulation. The characterizations are obtained by examining the time-dependent evolution of the information theoretic quantities. More specifically, we consider Shannon entropy, mutual information, fidelity, and relative entropy to characterize the weak measurement dynamics. Our results provide an information theoretic analysis of the weak measurement process and highlight the dynamical nature of information extraction and reversibility in the weak measurement processes.