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arXiv · 1712.06877

Observation of time quasicrystal and its transition to superfluid time crystal

S. Autti·G. E. Volovik·V. B. Eltsov
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Abstract

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. When the drive is turned off, the self-sustained coherent precession lives a macroscopically-long time, now representing a time crystal with broken symmetry with respect to continuous time translations. Additionally, the magnon condensate manifests spin superfluidity, justifying calling the obtained state a time supersolid or a time super-crystal.

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S. Autti, G. E. Volovik, V. B. Eltsov. 2017-12-19. Observation of time quasicrystal and its transition to superfluid time crystal. https://doi.org/10.1103/physrevlett.120.215301

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