Group Seminar at LMU: Chiral orbital order of interacting bosons without higher bands
Prof. Marco DiLiberto, University of Padova
Group Seminar at LMU seminar room H107 and zoom
Tuesday, May 2nd, 09:00am (MEZ)
Ultracold atoms loaded into higher Bloch bands provide an elegant setting for realizing many-body quantum states that spontaneously break time-reversal symmetry through the formation of chiral orbital order. The applicability of this strategy remains nonetheless limited due to the finite lifetime of atoms in high-energy bands. Here we introduce an alternative framework, suitable for bosonic gases, which builds on assembling square plaquettes pierced by a π flux (half a magnetic-flux quantum). This setting is shown to be formally equivalent to an interacting bosonic gas loaded into p-orbitals, and we explore the consequences of the resulting chiral orbital order, both for weak and strong on-site interactions. We demonstrate the emergence of a chiral superfluid vortex lattice, exhibiting a long-lived gapped collective mode that is characterized by local chiral currents. This chiral superfluid phase is shown to undergo a phase transition to a chiral Mott insulator for sufficiently strong interactions. Our work establishes coupled π-flux plaquettes as a practical route for the emergence of orbital order and chiral phases of matter.
Marco Di Liberto and Nathan Goldman
Phys. Rev. Research 5, 023064 – Published 27 April 2023