Transferring quantum states efficiently between distant nodes of an information processing circuit is of paramount importance for scalable quantum computing. We report on an observation of a perfect state transfer protocol on a lattice, thereby demonstrating the general concept of transporting arbitrary quantum information with high fidelity. Coherent transfer over 19 sites is realized by utilizing judiciously designed optical structures consisting of evanescently coupled waveguide elements. We provide unequivocal evidence that such an approach is applicable in the quantum regime, for both bosons and fermions, as well as in the classical limit. Our results illustrate the potential of the perfect state transfer protocol as a promising route towards integrated quantum computing on a chip

We study a system composed of two nonidentical qubits coupled to a singlemode quantum field. We calculate the spectra of the system in the deep-strongcoupling regime via perturbation theory up to second-order corrections and show that it converges to two forced oscillator chains for cases well into that regime. Our predictions are confirmed by the numerical calculation of the spectra using a parity decomposition of the corresponding Hilbert space. The numerical results point to two interesting types of behavior in the ultra-strongcoupling regime: the rotating wave approximation is valid for some particular cases and there exist crossings in the spectra within each parity subspace. We also present the normal modes of the system and give an example of the time evolution of the mean photon number, population inversion, von Neumann entropy and Wootters concurrence in the ultra-strong-and deep-strong-coupling regimes.

Diffraction is one of the universal phenomena of physics, and a way to overcome it has always represented a challenge for physicists. In order to control diffraction, the study of structured waves has become decisive. Here, we present a specific class of nondiffracting spatially accelerating solutions of the Maxwell equations: the Weber waves. These nonparaxial waves propagate along parabolic trajectories while approximately preserving their shape. They are expressed in an analytic closed form and naturally separate in forward and backward propagation. We show that the Weber waves are self-healing, can form periodic breather waves and have a well-defined conserved quantity: the parabolic momentum. We find that our Weber waves for moderate to large values of the parabolic momenta can be described by a modulated Airy function. Because the Weber waves are exact time-harmonic solutions of the wave equation, they have implications for many linear wave systems in nature, ranging from acoustic, electromagnetic and elastic waves to surface waves in fluids and membranes. Gesellschaft and applications, e.g. particle and cell micromanipulation [4,5], plasma physics [6], nonlinear optics [7], plasmonics [8,9] and micromachining [10], among others.Recently, new nondiffractive accelerating waves called 'half a Bessel' waves were theoretically introduced [11] and experimentally verified [12]. These waves propagate along a circular trajectory; during a quarter of the circle they are quasi shape-preserving and after this, diffraction broadening takes over and the waves spread out. The importance of these waves consists in having the same characteristics as the paraxial accelerating beams [1-3] but in the nonparaxial regime, i.e. these waves can bend to broader angles. Therefore, the 'half a Bessel' waves allow one to extrapolate all the intriguing applications of accelerating beams to the nonparaxial regime, and because these waves are solutions to the wave equation, they have implications for many linear wave systems in nature, ranging from acoustic and elastic waves to surface waves in fluids and membranes. Therefore, a natural question is: are there other accelerating nondiffractive solutions to the wave equation?In this paper, we present new nonparaxial spatially accelerating shape-preserving waves: the Weber waves. These nonparaxial waves propagate along parabolic trajectories while approximately preserving their shape within a range of propagation distances. Our Weber waves, like the 'half a Bessel' waves, are self-healing, they can form breather waves, and they are a complete and orthogonal family of waves. The Weber waves naturally separate in forward and backward propagation, and they have an analytic closed-form solution.The 'half a Bessel' waves by construction break the circular symmetry and do not have a well-defined angular momentum. In contrast, we show that the Weber waves have a well-defined conserved quantity: the parabolic momentum. We found that our Weber waves for moderate to large values of the parabolic mom...

We present a class of waveguide arrays that is the classical analog of a quantum harmonic oscillator where the mass and frequency depend on the propagation distance. In these photonic lattices refractive indices and second neighbor couplings define the mass and frequency of the analog quantum oscillator, while first neighbor couplings are a free parameter to adjust the model.The quantum model conserves the Ermakov-Lewis invariant, thus the photonic crystal also posses this symmetry. * bmlara@inaoep.mx 1 arXiv:1403.1498v1 [physics.optics]

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