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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.

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The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request.

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We appreciate generous technical support from G. Popowich, P. Davis, S. Wilson, S. Hubele, L. Cooke and the following groups for lending us equipment for our initial measurements: J. Beamish, J. P. Davis, F. Hegmann, A. Lvovsky, W. Tittel, R. Wolkow. We also thank B. Sanders, Y.-C. Chen and C. O’Brien for useful discussions. We gratefully acknowledge funding from the Natural Science and Engineering Research Council of Canada (NSERC RGPIN-2014-06618, STPGP 494024–16), Canada Foundation for Innovation (CFI), Canada Research Chairs Program (CRC), Canadian Institute for Advanced Research (CIFAR), Alberta Innovates — Technology Futures (AITF) and the University of Alberta.

Author information

The ATS memory approach was proposed by E.S. with feedback from K.H. and L.J.L. The project was supervised by L.J.L. and E.S. The ultracold atom apparatus was designed by L.J.L., and it was built and commissioned by L.J.L., T.H. and E.S. The design of the experiments, the measurements and the analysis of the results were performed by E.S. and T.H. The numerical modelling of the ATS memory was performed by K.H. with input from E.S. The simulations and numerical analysis were performed by E.S. and A.R. with the guidance of K.H. The manuscript was written by E.S. and L.J.L. with feedback from all co-authors.

Competing interests

The authors declare no competing interests.

Correspondence to Erhan Saglamyurek or Lindsay J. LeBlanc.

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Fig. 1: ATS quantum memory protocol.
Fig. 2: Theoretical analysis of ATS memory performance versus established memory protocols.
Fig. 3: Experimental demonstration of ATS memory in cold atoms.
Fig. 4: Phase preservation and single-photon level operation.
Fig. 5: Dynamic control of memory bandwidth and temporal shaping of signal pulses.
Fig. 6: Demonstration of temporal-beam-splitting.