Selectively Activated Photon-Hopping, Cross-Kerr, and Two-Mode Squeezing via Flux Modulation of a Tunable Coupler

Access to a wide variety of qubit-qubit interactions on a single device is desirable for the analog simulation of disparate quantum systems. At the most basic level, a plaquette containing two superconducting transmon qubits connected both capacitively and inductively by a flux-tunable coupler has shown promise for accessing distinct coupling regimes, such as those in which the single excitation transfer coupling dominates over the cross-Kerr (ZZ) coupling, and vice versa. Access to these regimes and others on a larger device is expected to allow for the analog simulation of several physical phenomena including fractional Bloch oscillations, various spin-spin interactions, and lattice gauge theories. In this work, we show theoretically and demonstrate experimentally the ability to selectively enter into regimes in which the system dynamics are dominated by either single photon-hopping, two-mode squeezing, or cross-Kerr interactions. The primary interaction is solely determined by the DC flux bias point and choice of modulation frequency for the AC flux threading the tunable coupler. The ability to tune into and out of these coupling regimes demonstrates the ability of superconducting devices containing tunable couplers to perform as versatile analog quantum simulators.