Fig. 2: Time crystal two-level system.
a The distribution of L (green arrows) confines magnons in two local minima, hosting two adjacent time crystals: one in the bulk of the superfluid (blue blob) and the other one touching the free surface (red blob). In each time crystal, magnetisation is precessing coherently, which couples to measurement circuitry as shown in Fig. 1. b Magnons in the bulk modify the confining trap created by the L distribution. When the bulk population is large (cyan blob), the textural trap is widened (red arrows), which modifies also surface time crystal’s wave function (magenta blob). This increases the coupling between the states. Changes in the trap and the wave functions have been exaggerated for illustrational purposes. c The state of the two-level system (red arrow) can be illustrated using a Bloch sphere where radial distance corresponds to magnon number NB + NS, the relative phase between the time crystals’ precession corresponds to the azimuthal angle ϕ, and the polar angle θ describes the relative weights of the two-level basis states in the “superposition” (see Methods).
