报告题目 (Title)：Pattern Formation and Exotic Order in Driven-Dissipative Bose-Hubbard Systems（在驱动-耗散的玻色-哈伯德系统中的图案结构产生和新奇序）

报告人 (Speaker)：蔡子 研究员（上海交通大学）

报告时间 (Time)：2021年10月19日(周二) 10:30-12:00

报告地点 (Place)：校本部G309

邀请人(Inviter)：张永平

主办部门：理学院物理系

报告摘要：Modern experimental platforms such as superconducting circuit arrays call for the exploration of bosonic tight-binding models in unconventional situations with no counterpart in real materials. Here we investigate one such situation in which excitations are driven and damped by pairs, leading to pattern formation and exotic bosonic states emerging from a nonequilibrium quantum many-body system. Focusing on a two-dimensional driven-dissipative Bose-Hubbard model, we find that its steady states are characterized by the condensation of bosons around momenta lying on a “Bose surface,” a bosonic analog of the Fermi surface in solid-state systems. The interplay between instabilities generated by the driving, the nonlinear dissipative mode coupling, and the underlying lattice effect allows the system to equilibrate into an exotic superfluid state of bosons condensed on a closed ring in momentum space instead of discrete points. Such an unconventional state with a spatially uniform density distribution goes beyond the traditional scope of pattern formation and thus has no counterpart in the classical literature.