Observation of time quasicrystal and its transition to superfluid time crystal

Understand

We report experimental realization of a quantum time quasicrystal, and its transformation to a quantum time crystal.

• We study Bose-Einstein condensation of magnons, associated with coherent spin precession, created in a flexible trap in superfluid $^3$He-B.
• Under a periodic drive with an oscillating magnetic field, the coherent spin precession is stabilized at a frequency smaller than that of the drive, demonstrating spontaneous breaking of discrete time translation symmetry.
• The induced precession frequency is incommensurate with the drive, and hence the obtained state is a time quasicrystal.