Fig. 4: The trajectory evolution of the initial quantum state \(\left(\left|H\right\rangle +\left|V\right\rangle \right)/\sqrt{2}\) shown by a circle on the Bloch sphere in the \({{{{{{{\mathcal{APT}}}}}}}}\)-symmetric system for different values of a.
From: Experimental demonstration of coherence flow in PT- and anti-PT-symmetric systems
a 3D and b overhead views. All curves are theoretical results, whereas squares represent the measured quantum states in our experiment for different evolution times. Different color squares represent different values of a (blue square: a = 0.31, red square: a = 0.47, black square: a = 1.5, green square: a = 2.8). It is noteworthy that the coherences of quantum states on the purple circle are the same. No error bar is plotted, because it is difficult to show the error of a quantum state on the Bloch sphere.
