Coherent storage and manipulation of broadband photons via dynamically controlled Autler–Townes splitting

Photonic quantum information technologies rely on quantum memory for long-lived storage and coherent manipulation of short pulses of non-classical light. The optical quantum memories explored over the past two decades are based on various coherent light–matter interaction schemes, but despite impressive progress, practical memories featuring efficient, broadband and long-lived operation remain elusive, due to the technical demands and inherent limitations of the established schemes. Here, we introduce a technique for high-speed quantum memory and manipulation that overcomes these obstacles. This scheme relies on dynamically controlled absorption of light via the ‘Autler–Townes effect’, which mediates reversible transfer between photonic coherence and the collective ground-state coherence of the storage medium. We experimentally demonstrate proof-of-concept storage and signal processing capabilities of our protocol in a laser-cooled gas of rubidium atoms, including storage of nanoseconds-long single-photon-level laser pulses for up to a microsecond. This approach opens up new avenues in quantum optics, with immediate applications on atomic and solid-state platforms. A broadband-light storage technique using the Autler–Townes effect is demonstrated in a system of cold Rb atoms. It overcomes both inherent and technical limitations of the established schemes for high-speed and long-lived optical quantum memories.