Quench dynamics of a disordered array of dissipative coupled cavities

We investigate the mean-field dynamics of a system of interacting photons in an array of coupled cavities in presence of dissipation and disorder. We follow the evolution of on an initially prepared Fock state, and show how the interplay between dissipation and disorder affects the coherence properties of the cavity emission and that these properties can be used as signatures of the many-body phase of the whole array.Comment: 8 pages, 10 figures, new reference adde

On the radiative lifetime of free-moving two-dimensional excitons

A simple microscopic mechanism explaining the linear dependence of the radiative lifetime of free-moving two-dimensional excitons on their effective temperature is suggested. It is shown that there exists a characteristic effective temperature (of about few Kelvin) defined by the exciton-acoustic phonon interaction at which the radiative lifetime is minimal. Below this temperature the lifetime starts to increase with decreasing temperature. The correspondence with previous theoretical and experimental results is discussed.Comment: 5 pages, 3 figures. Final versio

Creation of entangled states in coupled quantum dots via adiabatic rapid passage

Quantum state preparation through external control is fundamental to established methods in quantum information processing and in studies of dynamics. In this respect, excitons in semiconductor quantum dots (QDs) are of particular interest since their coupling to light allows them to be driven into a specified state using the coherent interaction with a tuned optical field such as an external laser pulse. We propose a protocol, based on adiabatic rapid passage, for the creation of entangled states in an ensemble of pairwise coupled two-level systems, such as an ensemble of QD molecules. We show by quantitative analysis using realistic parameters for semiconductor QDs that this method is feasible where other approaches are unavailable. Furthermore, this scheme can be generically transferred to some other physical systems including circuit QED, nuclear and electron spins in solid-state environments, and photonic coupled cavities.Comment: 10 pages, 2 figures. Added reference, minor changes. Discussion, results and conclusions unchange

Microcavity polariton-like dispersion doublet in resonant Bragg gratings

Periodic structures resonantly coupled to excitonic media allow the existence of extra intragap modes ('Braggoritons'), due to the coupling between Bragg photon modes and 3D bulk excitons. This induces unique and unexplored dispersive features, which can be tailored by properly designing the photonic bandgap around the exciton resonance. We report that one-dimensional Braggoritons realized with semiconductor gratings have the ability to mimic the dispersion of quantum-well microcavity polaritons. This will allow the observation of new nonlinear phenomena, such as slow-light-enhanced nonlinear propagation and an efficient parametric scattering at two 'magic frequencies'

Studying Light-Harvesting Models with Superconducting Circuits

The process of photosynthesis, the main source of energy in the animate world, converts sunlight into chemical energy. The surprisingly high efficiency of this process is believed to be enabled by an intricate interplay between the quantum nature of molecular structures in photosynthetic complexes and their interaction with the environment. Investigating these effects in biological samples is challenging due to their complex and disordered structure. Here we experimentally demonstrate a new approach for studying photosynthetic models based on superconducting quantum circuits. In particular, we demonstrate the unprecedented versatility and control of our method in an engineered three-site model of a pigment protein complex with realistic parameters scaled down in energy by a factor of $10^5$. With this system we show that the excitation transport between quantum coherent sites disordered in energy can be enabled through the interaction with environmental noise. We also show that the efficiency of the process is maximized for structured noise resembling intramolecular phononic environments found in photosynthetic complexes.Comment: 8+12 pages, 4+12 figure

Broadband enhancement of light emission in silicon slot waveguides

We investigate the light emission properties of electrical dipole emitters inside 2-dimensional (2D) and 3-dimensional (3D) silicon slot waveguides and evaluate the spontaneous emission enhancement (F_p) and waveguide coupling ratio (β). Under realistic conditions, we find that greater than 10-fold enhancement in F_p can be achieved, together with a β as large as 0.95. In contrast to the case of high Q optical resonators, such performance enhancements are obtained over a broad wavelength region, which can cover the entire emission spectrum of popular optical dopants such as Er. The enhanced luminescence efficiency and the strong coupling into a limited set of well-defined waveguide modes enables a new class of power-efficient, CMOS-compatible, waveguide-based light sources

Strong and weak coupling limits in optics of quantum well excitons

A transition between the strong (coherent) and weak (incoherent) coupling limits of resonant interaction between quantum well (QW) excitons and bulk photons is analyzed and quantified as a function of the incoherent damping rate caused by exciton-phonon and exciton-exciton scattering. For confined QW polaritons, a second, anomalous, damping-induced dispersion branch arises and develops with increasing damping. In this case, the strong-weak coupling transition is attributed to a critical damping rate, when the intersection of the normal and damping-induced dispersion branches occurs. For the radiative states of QW excitons, i.e., for radiative QW polaritons, the transition is described as a qualitative change of the photoluminescence spectrum at grazing angles along the QW structure. Furthermore, we show that the radiative corrections to the QW exciton states with in-plane wavevector approaching the photon cone are universally scaled by an energy parameter rather than diverge. The strong-weak coupling transition rates are also proportional to the same energy parameter. The numerical evaluations are given for a GaAs single quantum well with realistic parameters.Comment: Published in Physical Review B. 29 pages, 12 figure

Programming Light-Harvesting Efficiency Using DNA Origami.

The remarkable performance and quantum efficiency of biological light-harvesting complexes has prompted a multidisciplinary interest in engineering biologically inspired antenna systems as a possible route to novel solar cell technologies. Key to the effectiveness of biological "nanomachines" in light capture and energy transport is their highly ordered nanoscale architecture of photoactive molecules. Recently, DNA origami has emerged as a powerful tool for organizing multiple chromophores with base-pair accuracy and full geometric freedom. Here, we present a programmable antenna array on a DNA origami platform that enables the implementation of rationally designed antenna structures. We systematically analyze the light-harvesting efficiency with respect to number of donors and interdye distances of a ring-like antenna using ensemble and single-molecule fluorescence spectroscopy and detailed Förster modeling. This comprehensive study demonstrates exquisite and reliable structural control over multichromophoric geometries and points to DNA origami as highly versatile platform for testing design concepts in artificial light-harvesting networks.A. W. C. acknowledges support from the Winton Programme for the Physics of Sustainability. U. F. K. was partly supported by an ERC starting grant (PassMembrane, EY 261101). E. A.H. acknowledges support from Janggen-Pöhn Stiftung and the Schweizerischer Nationalfonds (SNF). P. T. acknowledges support by a starting grant (SiMBA, EU 261162) of the European Research Council (ERC). B. W. gratefully acknowledges support by the Braunschweig International Graduate School of Metrology B-IGSM and the DFG Research Training Group GrK1952/1 ‘Metrology for Complex Nanosystems’. P. M. thankfully acknowledges the support of the EPSRC Centre for Doctoral Training in Sensor Technologies and Applications EP/L015889/1.This is the final version of the article. It first appeared from ACS via https://doi.org/10.1021/acs.nanolett.5b0513