  Superconducting quantum processors are a compelling platform for analog
quantum simulation due to the precision control, fast operation, and
site-resolved readout inherent to the hardware. Arrays of coupled
superconducting qubits natively emulate the dynamics of interacting particles
according to the Bose-Hubbard model. However, many interesting condensed-matter
phenomena emerge only in the presence of electromagnetic fields. Here, we
emulate the dynamics of charged particles in an electromagnetic field using a
superconducting quantum simulator. We realize a broadly adjustable synthetic
magnetic vector potential by applying continuous modulation tones to all
qubits. We verify that the synthetic vector potential obeys requisite
properties of electromagnetism: a spatially-varying vector potential breaks
time-reversal symmetry and generates a gauge-invariant synthetic magnetic
field, and a temporally-varying vector potential produces a synthetic electric
field. We demonstrate that the Hall effect--the transverse deflection of a
charged particle propagating in an electromagnetic field--exists in the
presence of the synthetic electromagnetic field.
