Fig. 3: The evolution of coherence for three initial quantum states in the \({{{{{{{\mathcal{APT}}}}}}}}\)-symmetric system.
From: Experimental demonstration of coherence flow in PT- and anti-PT-symmetric systems
a The initial state \(\left|H\right\rangle\), b the initial state \((\left|H\right\rangle +\left|V\right\rangle )/\sqrt{2}\), whereas c is for the initial state \((\left|H\right\rangle +\sqrt{3}\left|V\right\rangle )/2\). In a and c, the coherence evolution exhibits periodic backflow when a = 1.5 (black curve) and a = 2.8 (green curve) (the \({{{{{{{\mathcal{APT}}}}}}}}\) symmetry unbroken regime), whereas the PSV of coherence occurs when a = 0.31 (blue curve) and a = 0.47 (red curve) (the \({{{{{{{\mathcal{APT}}}}}}}}\) symmetry broken regime). In b, coherence is conserved and does not change over time t, independent of a. In a and c, T = 2.81 for a = 1.5 and T = 1.20 for a = 2.8. All curves are theoretical results, whereas the dots are the experimental data. The experimental errors of 1 SD are estimated from the statistical variation of photon counts, which satisfy the Poisson distribution.
