Pump 'n' Dump - High Fidelity Communication with Lossy Microwave Links: Part 2

We realize a new scheme for entangling two superconducting cavity qubits in separate modules while avoiding link loss. The cavities are connected via a 5cm long superconducting coaxial cable with an FSR of 2 GHz. When we switch on parametric coupling between each module and a single standing mode in the cable, we can treat the cable mode as a 'dump mode' and use interference between the two couplings to generate entanglement. We prepare Bell states in the coherent state basis with 93% state fidelity and 37% success probability. This is possible even though the cable loss rate is 4x faster than our cavity-cable coupling rate, demonstrating our scheme's utility even in the presence of substantial link loss. Finally, we use this Bell state as a resource to deterministically teleport a qubit from one module to another with 90% transfer fidelity. Our work shows standing wave mode communication channels are a useful and still largely unexplored paradigm for near-term modular devices.