title: Qubit lattice coherence induced by electromagnetic pulses in superconducting metamaterials.
abstract: Quantum bits (qubits) are at the heart of quantum information processing schemes. Currently, solid-state qubits, and in particular the superconducting ones, seem to satisfy the requirements for being the building blocks of viable quantum computers, since they exhibit relatively long coherence times, extremely low dissipation, and scalability. The possibility of achieving quantum coherence in macroscopic circuits comprising Josephson junctions, envisioned by Legett in the 1980's, was demonstrated for the first time in a charge qubit; since then, the exploitation of macroscopic quantum effects in low-capacitance Josephson junction circuits allowed for the realization of several kinds of superconducting qubits. Furthermore, coupling between qubits has been successfully achieved that was followed by the construction of multiple-qubit logic gates and the implementation of several algorithms. Here it is demonstrated that induced qubit lattice coherence as well as two remarkable quantum coherent optical phenomena, i.e., self-induced transparency and Dicke-type superradiance, may occur during light-pulse propagation in quantum metamaterials comprising superconducting charge qubits. The generated qubit lattice pulse forms a compound "quantum breather" that propagates in synchrony with the electromagnetic pulse. The experimental confirmation of such effects in superconducting quantum metamaterials may open a new pathway to potentially powerful quantum computing.
authors.affiliation: Crete Center for Quantum Complexity and Nanotechnology, Department of Physics, University of Crete, P. O. Box 2208, 71003 Heraklion, Greece.|University of Belgrade, "Vinča" Institute of Nuclear Sciences, Laboratory for Theoretical and Condensed Matter Physics, P.O. Box 522, 11001 Belgrade, Serbia.|National University of Science and Technology MISiS, Leninsky prosp. 4, Moscow, 119049, Russia.
authors.forename: Z
authors.initials: Z
authors.lastname: Ivić
authors.affiliation: Crete Center for Quantum Complexity and Nanotechnology, Department of Physics, University of Crete, P. O. Box 2208, 71003 Heraklion, Greece.|National University of Science and Technology MISiS, Leninsky prosp. 4, Moscow, 119049, Russia.|Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, P.O. Box 1527, 71110 Heraklion, Greece.
authors.forename: N
authors.initials: N
authors.lastname: Lazarides
authors.affiliation: Crete Center for Quantum Complexity and Nanotechnology, Department of Physics, University of Crete, P. O. Box 2208, 71003 Heraklion, Greece.|National University of Science and Technology MISiS, Leninsky prosp. 4, Moscow, 119049, Russia.|Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, P.O. Box 1527, 71110 Heraklion, Greece.|Department of Physics, School of Science and Technology, Nazarbayev University, 53 Kabanbay Batyr Ave., Astana 010000, Kazakhstan.
authors.forename: G P
authors.initials: GP
authors.lastname: Tsironis