Qubit transfer errors fall to a quadratic level with STIRAP

Hong Jiang, Carlos Barahona-Pascual and Juan José García-Ripoll at the Instituto de Física Fundamental, IFF-CSIC, demonstrate a new approach to quantum state transfer that achieves a quadratic infidelity floor of O((γτ)^2). Their work addresses a gap in the theoretical understanding of where photon travel time is comparable to an emitter’s lifetime, a regime increasingly relevant to current circuit-QED hardware. The researchers used a Delay Differential Equation framework to reveal that emitters spontaneously synchronize into Rabi oscillations driven by photon echoes, enabling more efficient transfer via the STIRAP protocol than existing methods, even when accounting for signal retardation. These results establish photon-echo synchronization as a resource for quantum state transfer. Spectral analysis reveals a complex structure of eigenfrequencies and spectral weights dependent on the coupling parameter γτ and the qubit’s detuning Δ from the quantum link’s modes, providing insight into the behavior of emitters in short quantum links. This detailed understanding…