Coherence protection in coupled quantum systems

Cammack, H. M. and Kirton, P. and Stace, T. M. and Eastham, P. R. and Keeling, J. and Lovett, B. W. (2018) Coherence protection in coupled quantum systems. Physical Review A, 97 (2). 022103. ISSN 2469-9926 (

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The interaction of a quantum system with its environment causes decoherence, setting a fundamental limit on its suitability for quantum information processing. However, we show that if the system consists of coupled parts with different internal energy scales then the interaction of one part with a thermal bath need not lead to loss of coherence from the other. Remarkably, we find that the protected part can remain coherent for longer when the coupling to the bath becomes stronger or the temperature is raised. Our theory will enable the design of decoherence-resistant hybrid quantum computers.