Recently, Prof. Zi Cai ’s research team from School of Physics and Astronomy, SJTU published a research paper titled “Symmetry protected topological edge modes and emergent partial time reversal symmetry breaking in open quantum many-body systems” in Physical Review Letters, a top international physics journal.

Symmetry-protected topological edge modes are one of the most remarkable phenomena in topological physics. In this paper, we formulate and quantitatively examine the effect of a quantum bath on these topological edge modes. Using the density matrix renormalization group method, we study the ground state of a composite system of spin-1 quantum chain, where the system and the bath degrees of freedom are treated on the same footing. We focus on the dependence of these edge modes on the global and partial symmetries of system-bath coupling and on the features of the quantum bath. It is shown that the time-reversal symmetry(TRS) plays a special role for an open quantum system, where an emergent partial TRS breaking will result in a TRS-protected topological mode diffusing from the system edge into the bath, thus make it useless for quantum computation.

This work is collaborated with Prof. Wei Li’s group in Beihang University. Zijian Wang, an undergraduate student in Zhiyuan College, is the first author of this paper, and Prof. Wei Li and Zi Cai are the corresponding authors. We acknowledge the grants from the National Key Research and Development Program of China , NSFC of China, and  Shanghai Municipal Science and Technology Major Project .

Link：https://link.aps.org/doi/10.1103/PhysRevLett.126.237201

Zijian Wang#, Qiaoyi Li#, Wei Li* and Zi Cai*,  “Symmetry protected topological edge modes and emergent partial time reversal symmetry breaking in open quantum many-body systems”，Phys. Rev. Lett. 126, 237201 (2021)