Researchers Ji Zou, Valerii K. Kozin, Daniel Loss, and Jelena Klinovaja, affiliated with the University of Basel in Switzerland, have uncovered a novel phenomenon in coupled condensates that could have implications for the energy sector, particularly in the development of advanced energy storage and conversion technologies.
In their study, published in the journal Physical Review Letters, the researchers explored the behavior of three mutually coupled condensates, which are systems where particles occupy the same quantum state. They found that when these condensates are coupled in a nonreciprocal manner, meaning the influence between them is not equal, a rich variety of dynamic phases emerge.
One of the most striking findings was the emergence of an alternating current (ac) Josephson-like effect. Typically, the Josephson effect, which is the flow of current between two superconductors, requires an external bias. However, in this case, the researchers observed an autonomous oscillatory current without any external bias, driven by the interplay between nonreciprocity and nonlinearity in the coupled condensates.
This ac phase is characterized by the emergence of two distinct frequencies. One is associated with the precession of the global U(1) Goldstone mode, a type of collective excitation in the system. The other is linked to a stabilized limit cycle in a five-dimensional phase space, a complex dynamic behavior that the researchers observed.
The researchers also examined how instabilities develop in other phases, such as ferromagnetic and vortex states, and how these instabilities drive transitions into the ac regime. They found that the transition is hysteretic, meaning that phases with different winding numbers destabilize under distinct conditions, reflecting their inherently different nonlinear structures.
The practical applications of this research for the energy sector are still under exploration. However, the discovery of bias-free autonomous oscillatory currents could potentially lead to more efficient energy storage and conversion devices. The rich landscape of dynamical phases uncovered in this study could also inspire new approaches to controlling and manipulating quantum systems for energy applications.
In summary, this research highlights the potential of nonreciprocity-driven novel dynamical phases in a broad class of condensate platforms, opening up new avenues for exploration in the field of energy science and technology.
This article is based on research available at arXiv.