Chicago scientists find new way to link quantum computers across US

Researchers at the University of Chicago have developed a breakthrough method to connect quantum computers over distances exceeding 1,200 miles, vastly surpassing the previous limit of a few kilometers. This advancement hinges on significantly extending the quantum coherence times of individual erbium atoms—from 0.1 milliseconds to over 10 milliseconds—enabling entangled atoms to maintain coherence long enough for long-distance quantum communication. The team demonstrated potential latency as low as 24 milliseconds, theoretically allowing quantum computers to link across distances up to 2,485 miles, such as between Chicago and Colombia. The key innovation lies in the fabrication technique: instead of the traditional Czochralski method, which melts and cools materials to form crystals, the researchers used molecular-beam epitaxy (MBE) to build rare-earth-doped crystals atom by atom. This bottom-up approach produced components with remarkably long-lived quantum coherence and high matrix crystallinity, enabling kilohertz-level optical linewidths and erbium qubit spin coherence times