In a spin nematic state, the annihilation of a pair of topological defects releases quadrupolar waves, reminiscent of gravitational waves in the universe.

Understanding what happens in regimes where quantum mechanics and general relativity interface is of fundamental interest.  That said, it is not an easy thing to find systems in which the effects of both are simultaneously measurable and relevant. Parallels in condensed matter systems can provide experimentally accessible alternatives for a the exploration of a wide array of high-energy and gravitational phenomena beyond experimental control, and additionally bring them into a regime where quantum mechanics also plays a relevant role.
In this work, we show that spin nematics offer a condensed matter avenue to reproduce gravitational waves. In particular, we show that the massless, spin-2 Goldstone Bosons of ferroquadrupolar nematics are in one-to-one correspondence with gravitational waves in flat spacetime, independent of lattice considerations.  We then use simulation to illustrate the generation of such nematic waves, which mediate the attractive interaction between vortices in a two-dimensional realization of the ferroquadrupolar nematic. We also suggest that both the vortices and analogue waves are realizable in spinor condensates.