Qubit lattice coherence induced by electromagnetic pulses in superconducting metamaterials

Shiro Kawabata

Zoran M. Ivić, N. Lazarides, Giorgos P. Tsironis

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.

P. Macha, G. Oelsner, Jan-Michael Reiner +7 more

N. Lazarides, Zoran M. Ivić, George P. Tsironis

Superconducting quantum bits (qubits) are at the heart of quantum information processing schemes since they satisfy the requirements for being the building blocks of viable quantum computers. Here it is shown that quantum coherence, in the form of population inversion pulses, is induced by self-induced transparent electromagnetic pulses propagating in a quantum metamaterial comprising superconducting charge qubits. The experimental confirmation of that effect may open a new pathway to potentially powerful quantum computing.

M. R. Beasley

Zoran M. Ivić, N. Lazarides, Giorgos P. Tsironis

We introduce a quantum superconducting metamaterial design constituted of flux qubits that operate as artificial atoms and analyze the dynamics of an injected electromagnetic pulse in the system. Qubit-photon interaction affects dramatically the nonlinear photon pulse propagation. We find analytically that the well known atomic phenomenon of self induced transparency may occur in this metamaterial as well and may lead to significant control over the optical pulse propagating properties. Specifically, the pulse may be slowed down substantially or even be stopped. These pulse properties depend crucially on the inhomogeneous broadening of the levels of the artificial atoms.