Cooperative robustness to static disorder: Superradiance and localization in a nanoscale ring to model light-harvesting systems found in nature

Abstract

We analyze a 1-d ring structure composed of many two-level systems, in the limit where only one excitation is present. The two-level systems are coupled to a common environment, where the excitation can be lost, which induces super and subradiant behavior, an example of cooperative quantum coherent effect. We consider time-independent random fluctuations of the excitation energies. This static disorder, also called inhomogeneous broadening in literature, induces Anderson localization and is able to quench Superradiance. We identify two different regimes: i) weak opening, in which Superradiance is quenched at the same critical disorder at which the states of the closed system localize; ii) strong opening, with a critical disorder strength proportional to both the system size and the degree of opening, displaying robustness of cooperativity to disorder. Relevance to photosynthetic complexes is discussed.

Water Bridging Dynamics of Polymerase Chain Reaction in the Gauge Theory Paradigm of Quantum Fields

“…These remarks may account for the stability and efficiency of the PCR process against the high temperatures (up to 95 • C) of the various thermal cycles, otherwise inexplicable in a purely statistical approach based on molecular kinematics. These kinds of enhancement phenomena for the coupling constants are well known to occur in superradiance and cooperative two-level systems [33,34]. As a result, the macroscopic stability of the system follows since it is protected against quantum fluctuations in the microscopic short-range dynamics, and, for sufficiently large N, against thermal fluctuations, unless k B T is of the same order or larger than the height of the protective energy gap.…”

Excitation injector in an atomic chain: Long-range transport and efficiency amplification

“…As a matter of fact, it already has proven to be useful in numerous fields such as organic photovoltaic cells [6], quantum information [7], and more generally, nano-scale technologies [1]. In addition, the experimental observations of light-harvesting proteins, such as the FMO complex [8], have also triggered a lot of interest [9][10][11][12]. All these systems require energy to be transported within quantum systems over distances that might be relatively large, and with as little losses as possible.…”

Superradiance at the localization-delocalization crossover in tubular chlorosomes

“…It has been studied for supramolecular complexes and in the light-harvesting apparatus of bacterial photosynthesis [18,19]. In the presence of disorder, static or dynamic, superradiance is quenched, although, in a tight-binding model in a ring superradiance persists for disorder strengths below a critical value even in a regime with strong coupling to the external environment [20]. The optical properties of one-dimensional disordered excitonic systems have been studied extensively, specially in the context of applications to J-aggregates [21,22].…”