Yang Jiaying, Khanahmadi Maryam, Strandberg Ingrid, Gaikwad Akshay, Castillo-Moreno Claudia, Kockum Anton Frisk, Ullah Muhammad Asad, Johansson Göran, Eriksson Axel Martin, Gasparinetti Simone
Chalmers University of Technology, Department of Microtechnology and Nanoscience, SE-412 96 Göteborg, Sweden.
Ericsson Research, Ericsson AB, SE-164 83 Stockholm, Sweden.
Phys Rev Lett. 2025 Jun 20;134(24):240803. doi: 10.1103/PhysRevLett.134.240803.
A distributed quantum computing network requires a quantum communication channel between spatially separated processing units. In superconducting circuits, such a channel can be implemented based on propagating microwave photons to encode and transfer quantum information between an emitter and a receiver. However, traveling microwave photons can be lost during the transmission, leading to the failure of information transfer. Heralding protocols can be used to detect such photon losses. In this Letter, we propose such a protocol and experimentally demonstrate a frequency-bin encoding method of microwave photonic modes using superconducting circuits. We deterministically encode the quantum information from a superconducting qubit by simultaneously emitting its information into two photonic modes at different frequencies, with a process fidelity of 94.9%. The frequency-bin-encoded photonic modes can be used, at the receiver processor, to detect the occurrence of photon loss. Our Letter thus provides a reliable method to implement high-fidelity quantum state transfer in a distributed quantum computing network, incorporating error detection to enhance performance and accuracy.
