Information-reality complementarity in photonic weak measurements

The emergence of realistic properties is a key problem in understanding the quantum-to-classical transition. In this respect, measurements represent a way to interface quantum systems with the macroscopic world: these can be driven in the weak regime, where a reduced back-action can be imparted by choosing meter states able to extract different amounts of information. Here we explore the implications of such weak measurement for the variation of realistic properties of two-level quantum systems pre- and postmeasurement, and extend our investigations to the case of open systems implementing the measurements.

Figure 1

Experimental behavior of $\mathrm{\Delta }\mathcal{R}$ as a function of the measurement strength $\epsilon$. The measured values correspond to the points. The blue solid line corresponds to the prediction, and the solid orange line corresponds to the bound (4).

Figure 2

Experimental behavior of $\mathrm{\Delta }I$ as a function of the measurement strength $\epsilon$. The measured values correspond to the points. The red solid line corresponds to the prediction (7).

Figure 3

Experimental behavior of $\mathrm{\Delta }\mathcal{R}$ as a function of the entropy of the initial meter state $S_m$, for $\theta ={16}^{\circ }$. The measured values correspond to the points. The purple solid line corresponds to the prediction.