Fig. 1: Experimental setup and current measurement in a many-body system with complex tunnelling.
From: Strongly interacting Meissner phases in large bosonic flux ladders
a, HBH model on two leg ladders, parameterized by a real-valued tunnel coupling J along the leg direction, complex-valued tunnel coupling Keirφ along the rung direction and a repulsive on-site interaction U. Here r is the rung index, and l = 1 and 2 indexes the leg. Persistent particle currents emerge due to the synthetic magnetic field (middle ladder, blue arrows). b, Measurement of currents in a many-body system with complex tunnelling. After quenching the interactions to zero via a Feshbach resonance, the leg current operator is measured via a DW basis rotation with real coupling (right), whereas for the rung current operator, it has to be performed in a driven DW with complex coupling (left). \({\hat{\sigma }}_{x}\) is the Pauli X operator and T is the tunnelling time in the DW (as defined in the main text).
