Fig. 1: Bound states of photons.
From: Formation of robust bound states of interacting microwave photons
a, In a 1D chain of qubits hosting bound states, an initial state with adjacent photons evolves into a superposition of states in which the photons remain bound together. b, Interactions between photons can lead to destructive interference for paths in which photons do not stay together, thus suppressing separation. c, Schematic of the gate sequence used in this work. Each cycle of evolution contains two layers of fSim gates that connect the even and odd pairs, respectively. The fSim gate has three controllable parameters, which set the kinetic energy (θ), the interaction strength (ϕ) and a synthetic magnetic flux (β). The median gate infidelity, measured with cross-entropy benchmarking, is 1.1% (see Supplementary Information).
