Hamiltonian benchmark of a solid-state spin-photon interface for computation
Phys. Rev. B 114, 115306 – Published 28 August, 2026
DOI: https://doi.org/10.1103/x983-pznx
Abstract
Quantum interfaces are a cornerstone of photonic quantum computing protocols. They consist of quantum emitters coupled to propagating light pulses, enabling the reversible transfer of information between emitter degrees of freedom, such as energy or spin, and photonic degrees of freedom, including polarization or photon number. In practice, propagating light pulses are multimode wave packets and can undergo substantial spectral distortions during their interactions with the emitters. This effect introduces an intrinsic source of decoherence that has been largely overlooked in early proposals based on idealized monochromatic fields. Here, we investigate the consequences of this decoherence for three key protocols implemented with a solid-state spin-photon interface: the generation of photon-number superposition states, the realization of a controlled photon-photon gate, and the generation of photonic cluster states. Our analysis is based on a full Hamiltonian description of the joint emitter-field dynamics. The model further incorporates realistic features of the quantum dot spin dynamics, including decoherence induced by hyperfine interactions. From this framework, we derive analytical expressions for the resulting fidelity losses. Our results demonstrate a pronounced degradation of performance for the photon-photon gate, a moderate reduction in the fidelity of linear photonic cluster states, and a negligible impact on the generation of photon-number superpositions. These findings highlight the critical role of multimode effects in assessing the feasibility and scalability of photonic quantum information protocols.
