Deterministic generation of large-scale photonic GHZ states utilizing spin echo in a solid-state quantum light source
Researchers developed a semiconductor quantum dot device to deterministically generate large-scale photonic Greenberger-Horne-Zeilinger (GHZ) states, involving more than a dozen indistinguishable photons, at rates exceeding 1 GHz. The key innovation is a 'natural spin echo' mechanism that uses opposite spin precession directions in the excited and ground states of the quantum dot to cancel phase accumulation, leading to record entanglement robustness.