2020/03/13 by Samuli Autti, Petri J. Heikkinen, Jere T. Mäkinen +3 · 1 citation
Physics and Astronomy · #cond-mat.other #cond-mat.mes-hall
paper · pdf · doi:10.1038/s41563-020-0780-y
7 pages, 2 figures
arxiv created 2020/03/13 · arxiv updated 2020/08/21
Quantum time crystals are systems characterised by spontaneously emerging periodic order in the time domain. A range of such phases has been reported. The concept has even been discussed in popular literature, and deservedly so: while the first speculation on a phase of broken time translation symmetry did not use the name "time crystal", it was later adopted from 1980's popular culture. For the physics community, however, the ultimate qualification of a new concept is its ability to provide predictions and insight. Confirming that time crystals manifest the basic dynamics of quantum mechanics is a necessary step in that direction. We study two adjacent quantum time crystals experimentally. The time crystals, realised by two magnon condensates in superfluid 3He-B, exchange magnons leading to opposite-phase oscillations in their populations -- AC Josephson effect -- while the defining periodic motion remains phase coherent throughout the experiment.