8,525 research outputs found
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
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