Fig. 4
From: Experimental observation of classical analogy of topological entanglement entropy
The designed work flow to obtain the classical analogy of the state |Ξ〉4 in the DSP module. All eight signals in the channels {h1, v1, …, h4, v4} fed into the DSP are digitally down-converted to their own frequencies as planned. After a measuring process through the PROJ part followed by several mixing and filtering processes for multiplex signals, the desired frequency components selected by a collections of FFT-based digital filters {FFT1, …, FFT6} are adjusted by five modulators {d1, …, d5}, respectively, and we collect their joint complex amplitude denoted as A. Also, this procedure can be conveniently adjusted to simulate the state |Φg〉4
