Observation of Bloch Oscillations and Wannier-Stark Localization on a Superconducting Processor

In a crystal lattice system, a conduction electron can exhibit Bloch oscillations and Wannier-Stark localization (WSL) under a constant force, which has been observed in semiconductor superlattice, photonic waveguide array and cold atom systems. Here, we experimentally investigate the Bloch oscillations on a 5-qubit superconducting processor. We simulate the electron movement with spin (or photon) propagation. We find, in the presence of a linear potential, the propagation of a single spin charge is constrained. It tends to oscillate near the neighborhood of initial positions, which is a strong signature of Bloch oscillations and WSL. In addition, we use the maximum probability that a spin charge can propagate from one boundary to another boundary to represent the WSL length, and it is verified that the localization length is inversely correlated to the potential gradient. Remarkably, benefiting from the precise simultaneous readout of the all qubits, we can also study the thermal transport of this system. The experimental results show that, similar to the spin charges, the thermal transport is also blocked under a linear potential. Our work demonstrates possibilities for further simulation and exploration of the Bloch oscillation phenomena and other quantum physics using multiqubit superconducting quantum processor.