Extraordinary exciton conductance induced by strong coupling

We demonstrate that exciton conductance in organic materials can be enhanced by several orders of magnitude when the molecules are strongly coupled to an electromagnetic mode. Using a 1D model system, we show how the formation of a collective polaritonic mode allows excitons to bypass the disordered array of molecules and jump directly from one end of the structure to the other. This finding could have important implications in the fields of exciton transistors, heat transport, photosynthesis, and biological systems in which exciton transport plays a key role.Comment: Main text: 5 pages, 4 figures; Supplemental: 2 pages, 1 figure. Version 2: Updated reference to related work arXiv:1409.2550. Version 3: Updated to version accepted for publication in Physical Review Letter

Cavity-induced modifications of molecular structure in the strong coupling regime

In most theoretical descriptions of collective strong coupling of organic molecules to a cavity mode, the molecules are modeled as simple two-level systems. This picture fails to describe the rich structure provided by their internal rovibrational (nuclear) degrees of freedom. We investigate a first-principles model that fully takes into account both electronic and nuclear degrees of freedom, allowing an exploration of the phenomenon of strong coupling from an entirely new perspective. First, we demonstrate the limitations of applicability of the Born-Oppenheimer approximation in strongly coupled molecule-cavity structures. For the case of two molecules, we also show how dark states, which within the two-level picture are effectively decoupled from the cavity, are indeed affected by the formation of collective strong coupling. Finally, we discuss ground-state modifications in the ultra-strong coupling regime and show that some molecular observables are affected by the collective coupling strength, while others only depend on the single-molecule coupling constant.Comment: 12 pages, 8 figure

Quantum theory of collective strong coupling of molecular vibrations with a microcavity mode

We develop a quantum mechanical formalism to treat the strong coupling between an electromagnetic mode and a vibrational excitation of an ensemble of organic molecules. By employing a Bloch-Redfield-Wangsness approach, we show that the influence of dephasing-type interactions, i.e., elastic collisions with a background bath of phonons, critically depends on the nature of the bath modes. In particular, for long-range phonons corresponding to a common bath, the dynamics of the "bright state" (the collective superposition of molecular vibrations coupling to the cavity mode) is effectively decoupled from other system eigenstates. For the case of independent baths (or short-range phonons), incoherent energy transfer occurs between the bright state and the uncoupled dark states. However, these processes are suppressed when the Rabi splitting is larger than the frequency range of the bath modes, as achieved in a recent experiment [Shalabney et al., Nat. Commun. 6, 5981 (2015)]. In both cases, the dynamics can thus be described through a single collective oscillator coupled to a photonic mode, making this system an ideal candidate to explore cavity optomechanics at room temperature.Comment: 13 pages, 4 figure

Bighorn Sheep (Ovis Canadensis) Ecology and Demography in the North Dakota Badlands

The bighorn sheep (Oyis canadensis califomiana) in the North Dakota Badlands were studied in an effort to obtain baseline ecological data and examine the effects of human disturbance (primarily oil development) on their ranges, habitat use, movements and reproductive performance. The study was conducted from May and April, 1992 and 1993, respectively, through December of each year. Additionally, the summer of 1994 was used to complete habitat classification in the field. Eight bighorn ewes were captured by helicopter and net-gun in each of 2 primary study areas (one highly impacted by oil development and the other less impacted) and fitted with radio collars and ear tags. The radioed ewes were tracked and visually observed at least once a week - more frequently during the lambing season. As time permitted, the demographics and reproductive performance of 7 other free-ranging groups of bighorns were also monitored. The sheep did not occupy different ranges during different times of the year and no seasonal migration occurred. There was a high degree of home range fidelity and bighorns in the primary study areas still occupied the same ranges animals did more than 20 years ago. The non-vegetated habitat, associated with escape terrain, was preferred (P \u3c 0.05) for bedding in all seasons. Grass habitats were generally avoided for bedding in all seasons, except plateau tops in the fall. Trec/Shrub habitats were avoided (P \u3c 0.05) for all activities in all seasons. Within their ranges, sheep used some areas more heavily than others. These areas were always associated with escape terrain. Nearly 60% of their activity occurred on approximately 33% of their range, and 88% of their activity occurred within 100 m of escape terrain. Ewes with lambs were nervous, wary, and quick to flee. They were even more closely associated with the escape terrain. While production was high for some groups, lamb survival (recruitment) was low for most and non-existent for others. Predation and disease appeared to be major factors. Survival of sheep older than 4 months was high, with most mortality (rams) a result of the hurting season. While there was no significant difference in lamb recruitment between the 2 primary study areas (P \u3c 0.05). there were differences when ail areas were combined and categorized by level of disturbance. The recruitment of lambs was significantly higher (P \u3c 0.05) in areas with low levels of human disturbance than it was in areas with moderate or high levels

Discrimination, Retaliation, and the EEOC: The Circuit Split Over the Administrative Exhaustion Requirement in Title VII Claims

Title VII of the Civil Rights Act of 1964 established the procedure by which an individual may bring a claim of employment discrimination. Before an individual can sue an alleged violator of Title VII, that person must first file a charge with the Equal Employment Opportunity Commission (EEOC). In many cases, an individual who does not file an EEOC charge will see his or her case dismissed for failure to adhere to the administrative exhaustion requirement. Although seemingly simple, the administrative exhaustion requirement is not devoid of controversy. For nearly a decade, federal courts have been split over the issue of whether an individual who has filed an employment discrimination charge with the EEOC and who later alleges unlawful retaliation must file a subsequent EEOC charge on the retaliation claim. Some courts have recognized an exception to the administrative exhaustion requirement under circumstances such as these, whereby an individual could allege retaliation for the first time in district court so long as the alleged retaliation is like or reasonably related to the previously alleged discrimination. Other courts have ruled that no exceptions to the administrative exhaustion requirement should be made and that failure to file a subsequent retaliation charge precludes the claim. This Comment first details the purpose of Title VII. This Comment then examines the split among federal courts over whether courts should make exceptions to the administrative exhaustion requirement. Finally, this Comment concludes that to preserve the important functions of the charge-filing process-putting the employer and EEOC on notice of an alleged violation and allowing the employer and aggrieved party to engage in voluntary conciliation proceedings-courts should not make any exceptions to the administrative exhaustion requirement