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Enhancing coherent transport in a photonic network using controllable decoherence.

Biggerstaff DN, Heilmann R, Zecevik AA, Gräfe M, Broome MA, Fedrizzi A, Nolte S, Szameit A, White AG, Kassal I - Nat Commun (2016)

Bottom Line: It has been predicted that the efficiency of coherent transport can be enhanced through dynamic interaction between the system and a noisy environment.We report an experimental simulation of environment-assisted coherent transport, using an engineered network of laser-written waveguides, with relative energies and inter-waveguide couplings tailored to yield the desired Hamiltonian.Controllable-strength decoherence is simulated by broadening the bandwidth of the input illumination, yielding a significant increase in transport efficiency relative to the narrowband case.

View Article: PubMed Central - PubMed

Affiliation: Centre for Engineered Quantum Systems and Centre for Quantum Computation and Communication Technology, School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4072, Australia.

ABSTRACT
Transport phenomena on a quantum scale appear in a variety of systems, ranging from photosynthetic complexes to engineered quantum devices. It has been predicted that the efficiency of coherent transport can be enhanced through dynamic interaction between the system and a noisy environment. We report an experimental simulation of environment-assisted coherent transport, using an engineered network of laser-written waveguides, with relative energies and inter-waveguide couplings tailored to yield the desired Hamiltonian. Controllable-strength decoherence is simulated by broadening the bandwidth of the input illumination, yielding a significant increase in transport efficiency relative to the narrowband case. We show integrated optics to be suitable for simulating specific target Hamiltonians as well as open quantum systems with controllable loss and decoherence.

No MeSH data available.


Related in: MedlinePlus

Environment-assisted quantum transport (ENAQT).(a) Photosynthetic antenna complexes are networks of chlorophylls that collect and transfer solar energy. A well-studied example is the Fenna–Matthews–Olson complex of green sulphur bacteria, here depicted as a network of seven sites that transports excitation energy from initial site 1 to target site 3 (adapted with permission from ref. 49). Simulations have suggested that this transport may be enhanced by decoherence567. (b) We simulate an instance of ENAQT on a lattice of four sites, with site 1 initially excited and site 3 the target. If the detuning Δβ of site 4 equals C, one of the system eigenmodes has no occupancy at site 3 and cannot couple to the sink; by broadening the levels, decoherence breaks the condition Δβ=C, allowing all eigenmodes to couple to the sink and thus increasing transport efficiency. (c) Our simulator consists of four coupled waveguides arranged as shown (cross-section). The sink is modelled with a large array of closely coupled waveguides that transport light away from the main four waveguides. At the central wavelength λ0, waveguide 4 has propagation constant β+Δβ, while the others have propagation constant β. (d) Theoretical expectation of transport enhancement for this system, as a function of simulation length z and decoherence strength γ. The red bar indicates the region explored experimentally.
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f1: Environment-assisted quantum transport (ENAQT).(a) Photosynthetic antenna complexes are networks of chlorophylls that collect and transfer solar energy. A well-studied example is the Fenna–Matthews–Olson complex of green sulphur bacteria, here depicted as a network of seven sites that transports excitation energy from initial site 1 to target site 3 (adapted with permission from ref. 49). Simulations have suggested that this transport may be enhanced by decoherence567. (b) We simulate an instance of ENAQT on a lattice of four sites, with site 1 initially excited and site 3 the target. If the detuning Δβ of site 4 equals C, one of the system eigenmodes has no occupancy at site 3 and cannot couple to the sink; by broadening the levels, decoherence breaks the condition Δβ=C, allowing all eigenmodes to couple to the sink and thus increasing transport efficiency. (c) Our simulator consists of four coupled waveguides arranged as shown (cross-section). The sink is modelled with a large array of closely coupled waveguides that transport light away from the main four waveguides. At the central wavelength λ0, waveguide 4 has propagation constant β+Δβ, while the others have propagation constant β. (d) Theoretical expectation of transport enhancement for this system, as a function of simulation length z and decoherence strength γ. The red bar indicates the region explored experimentally.

Mentions: In most studies, ENAQT is about the efficiency of transport from a particular initial site to a particular target site, where the excitation is irreversibly trapped. In the case of a photosynthetic complex (Fig. 1a), trapping describes the transfer of excitons to a reaction center, where they drive charge separation. It can be modelled as irreversible coupling of the target site to a sink at rate κ. The efficiency is usually defined as the probability of finding the exciton in the sink after a certain time or, more commonly, in the long-time limit.


Enhancing coherent transport in a photonic network using controllable decoherence.

Biggerstaff DN, Heilmann R, Zecevik AA, Gräfe M, Broome MA, Fedrizzi A, Nolte S, Szameit A, White AG, Kassal I - Nat Commun (2016)

Environment-assisted quantum transport (ENAQT).(a) Photosynthetic antenna complexes are networks of chlorophylls that collect and transfer solar energy. A well-studied example is the Fenna–Matthews–Olson complex of green sulphur bacteria, here depicted as a network of seven sites that transports excitation energy from initial site 1 to target site 3 (adapted with permission from ref. 49). Simulations have suggested that this transport may be enhanced by decoherence567. (b) We simulate an instance of ENAQT on a lattice of four sites, with site 1 initially excited and site 3 the target. If the detuning Δβ of site 4 equals C, one of the system eigenmodes has no occupancy at site 3 and cannot couple to the sink; by broadening the levels, decoherence breaks the condition Δβ=C, allowing all eigenmodes to couple to the sink and thus increasing transport efficiency. (c) Our simulator consists of four coupled waveguides arranged as shown (cross-section). The sink is modelled with a large array of closely coupled waveguides that transport light away from the main four waveguides. At the central wavelength λ0, waveguide 4 has propagation constant β+Δβ, while the others have propagation constant β. (d) Theoretical expectation of transport enhancement for this system, as a function of simulation length z and decoherence strength γ. The red bar indicates the region explored experimentally.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835546&req=5

f1: Environment-assisted quantum transport (ENAQT).(a) Photosynthetic antenna complexes are networks of chlorophylls that collect and transfer solar energy. A well-studied example is the Fenna–Matthews–Olson complex of green sulphur bacteria, here depicted as a network of seven sites that transports excitation energy from initial site 1 to target site 3 (adapted with permission from ref. 49). Simulations have suggested that this transport may be enhanced by decoherence567. (b) We simulate an instance of ENAQT on a lattice of four sites, with site 1 initially excited and site 3 the target. If the detuning Δβ of site 4 equals C, one of the system eigenmodes has no occupancy at site 3 and cannot couple to the sink; by broadening the levels, decoherence breaks the condition Δβ=C, allowing all eigenmodes to couple to the sink and thus increasing transport efficiency. (c) Our simulator consists of four coupled waveguides arranged as shown (cross-section). The sink is modelled with a large array of closely coupled waveguides that transport light away from the main four waveguides. At the central wavelength λ0, waveguide 4 has propagation constant β+Δβ, while the others have propagation constant β. (d) Theoretical expectation of transport enhancement for this system, as a function of simulation length z and decoherence strength γ. The red bar indicates the region explored experimentally.
Mentions: In most studies, ENAQT is about the efficiency of transport from a particular initial site to a particular target site, where the excitation is irreversibly trapped. In the case of a photosynthetic complex (Fig. 1a), trapping describes the transfer of excitons to a reaction center, where they drive charge separation. It can be modelled as irreversible coupling of the target site to a sink at rate κ. The efficiency is usually defined as the probability of finding the exciton in the sink after a certain time or, more commonly, in the long-time limit.

Bottom Line: It has been predicted that the efficiency of coherent transport can be enhanced through dynamic interaction between the system and a noisy environment.We report an experimental simulation of environment-assisted coherent transport, using an engineered network of laser-written waveguides, with relative energies and inter-waveguide couplings tailored to yield the desired Hamiltonian.Controllable-strength decoherence is simulated by broadening the bandwidth of the input illumination, yielding a significant increase in transport efficiency relative to the narrowband case.

View Article: PubMed Central - PubMed

Affiliation: Centre for Engineered Quantum Systems and Centre for Quantum Computation and Communication Technology, School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4072, Australia.

ABSTRACT
Transport phenomena on a quantum scale appear in a variety of systems, ranging from photosynthetic complexes to engineered quantum devices. It has been predicted that the efficiency of coherent transport can be enhanced through dynamic interaction between the system and a noisy environment. We report an experimental simulation of environment-assisted coherent transport, using an engineered network of laser-written waveguides, with relative energies and inter-waveguide couplings tailored to yield the desired Hamiltonian. Controllable-strength decoherence is simulated by broadening the bandwidth of the input illumination, yielding a significant increase in transport efficiency relative to the narrowband case. We show integrated optics to be suitable for simulating specific target Hamiltonians as well as open quantum systems with controllable loss and decoherence.

No MeSH data available.


Related in: MedlinePlus