Quantum simulation of Bose-Hubbard ladders on superconducting qubits

Superconducting qubits are a promising platform for quantum simulation due to their natural implementation of the Bose-Hubbard Hamiltonian and flexibility in tuning system parameters. In these systems, a combination of onsite interactions and interference effects from synthetic magnetic fields gives rise to interesting quantum many-body dynamics and phases. Ladders of coupled one-dimensional chains are among the simplest lattices where effects from a magnetic field can be observed, and their reduced dimensionality maximizes the influence of onsite interactions. On a superconducting qubit device, tunablility of hopping strengths and synthetic magnetic fluxes enables access to various phases in this system. Here, we present the implementation of a ladder with superconducting qubits and demonstrate site-selective state preparation and microwave spectroscopy of many-particle states as well as site-specific correlation measurements, enabling exploration of interesting quantum many-body phases.