Measurement of Current Correlations and Bond Order Operators in a Chiral Superfluid Phase on a Superconducting Qubit Quantum Simulator

Superconducting qubits are a promising platform for quantum simulation of interacting systems due to site-specific control, flexible tunability and connectivity, and direct mapping to the Bose-Hubbard Hamiltonian. One interesting system is the triangular ladder, where the interplay of particle-particle interactions, geometric frustration, and magnetic flux lead to the existence of Meissner and chiral superfluid phases with distinct particle current signatures. We prepare such states in a superconducting qubit triangular lattice with tunable couplers and distinguish these phases of matter using current correlation measurements across different rungs, performed through an operation that maps current operator eigenstates to particle number eigenstates. Using a similar operation, we also measure the bond order across rungs to detect signatures of a bond-order insulator phase. Such methods have applications for preparing and measuring properties of various strongly interacting many-body phases with distinct geometries.