Pis’ma v ZhETF, vol. 105, iss. 2, pp. 110 – 111 2017 January 25 c Role of qubit-cavity entanglement for switching dynamics of quantum interfaces in superconductor metamaterials S.V.Remizov+∗, D. S. Shapiro+∗Ч1), A.N.Rubtsov+# +N.L.Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia ∗V.A.Kotel’nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 125009 Moscow, Russia ЧNational University of Science and Technology MISIS, 119049 Moscow, Russia #Russian Quantum Center, 143025 Skolkovo, Russia Submitted 25 October 2016 Resubmitted 24 November 2016 DOI: 10.7868/S0370274X17020126 Quantum metamaterials are hybrid systems consisting of arrays of qubits coupled to the photon modes of a cavity [1–4]. <...> In solid state structures the qubits are realized using nitrogen-vacancy (NV) centers in diamonds [5], and spins of 31P dopants in 28Si crystals [6] or Cr3+ in Al2O3 samples [7], and superconducting Josephson qubits [8]. <...> Frequency of excitation, given by an energy difference between ground and excited states, can be controllably tuned in a wide range using the external magnetic flux threading a loop of the qubit. <...> Modern technology allows for a production of metematerial structures obeying sophisticated geometry and low decoherence effects. <...> High nonlinearity of the qubit excitation spectrum, combined with low decoherence, gives rise to unusual properties of quantum metamaterials, distinguishing them from the linear-optical metastructures. <...> These unusual features are associated with intrinsic quantum dynamics of qubits and photon degrees of freedom. <...> A textbook example is the rotation on a Bloch sphere of the state of a single qubit subjected to an external field pulse. <...> This 1)e-mail: shapiro.dima@gmail.com 110 article is devoted to the role of quantum entanglement between qubit and cavity modes of the superconducting metamaterial. <...> Whereas it is generally clear that these correlation effects beyond Maxwell–Bloch scheme are revealed in strong-driving regimes, their quantitative role in an experimentally/technologically relevant situation is not yet studied. <...> At the same time, such study is highly motivated by the quantum technology development, because a realization of qubit gates and operation of quantum simulators assume applying <...>