Waveguide QED Analysis of Quantum-Coherent Links for Modular Quantum Computing

Waveguides potentially offer an effective medium for interconnecting quantum processors within a modular framework, facilitating the coherent quantum state transfer between the qubits across separate chips. In this work, we analyze a quantum communication scenario where two qubits are connected to a shared waveguide, whose resonance frequency may match or not match that of the qubits. Both configurations are simulated from the perspective of quantum electrodynamics (QED) to assess the system behavior and key factors that influence reliable inter-chip communication. The primary performance metrics analyzed are quantum state transfer fidelity and latency, considering the impact of key system parameters such as the qubit-waveguide detuning, coupling strength, waveguide decay rate, and qubit decay rate. We present the system design requirements that yield enhanced state transmission fidelity rates and lowered latency, and discuss the scalability of waveguide-mediated interconnects considering various configurations of the system.