Fig. 3
From: Observation of emergent momentum–time skyrmions in parity–time-symmetric non-unitary quench dynamics
Experimental results of n(k, t). Time-evolution of n(k, t) up to t = 6 for quench processes between (a) an initial unitary Floquet operator characterized by \((\theta _1^{\mathrm{i}} = \pi /4,\theta _2^{\mathrm{i}} = - \pi /2)\) and a final unitary Floquet operator characterized by \((\theta _1^{\mathrm{f}} = - \pi /2,\theta _2^{\mathrm{f}} = \pi /3)\) and (b) an initial non-unitary Floquet operator characterized by \((\theta _1^{\mathrm{i}} = \pi /4,\theta _2^{\mathrm{i}} = - \pi /2)\) and a final non-unitary Floquet operator characterized by \(\left( {\theta _1^{\mathrm{f}} = - \pi /2,\theta _2^{\mathrm{f}} = {\mathrm{{arcsin}}}\left( {\frac{1}{\alpha }{\mathrm{{cos}}}\frac{\pi }{6}} \right)} \right)\). The period of oscillations is t0 = 6 for all k. Fixed points (vertical dashed lines) are located at {−π, −π/2, 0, π/2} for unitary dynamics (a) and at {−0.4399π, −0.0099π, 0.5601π, 0.9901π} for non-unitary dynamics (b). Shading indicates experimental error bars that are due to photon-counting statistics
