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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.


Experimental setup and waveguide design.(a) Predicted dynamics of light in our waveguide array, as a function of z. The inset shows the predicted device output distribution for input at wavelength λ0. The sink array is sufficiently long that light reflecting from the far boundary fails to couple back into the system waveguides during the simulation. (b) A fibre-coupled, tunable Ti:sapphire laser in quasi-cw mode undergoes polarization control (Pol) before it is imaged into the sample using a 15 mm focal-length aspheric lens. The output is imaged via a 14 × telescope onto a variable slit, which collectively measures the total intensity output from the system, bath or all the waveguides using a large-area power-meter (PM). Alternatively, the output can be imaged onto a CCD camera for alignment and diagnostics. (c) CCD images of the output after 15 cm when illuminated at λ0=792.5 nm and at 830 nm. As designed, the light in the system waveguides is evenly distributed at λ0 apart from the target site, which is dark. In contrast, the target site is much brighter at 830 nm, indicating that more light will couple into the sink—a sign of ENAQT.
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f2: Experimental setup and waveguide design.(a) Predicted dynamics of light in our waveguide array, as a function of z. The inset shows the predicted device output distribution for input at wavelength λ0. The sink array is sufficiently long that light reflecting from the far boundary fails to couple back into the system waveguides during the simulation. (b) A fibre-coupled, tunable Ti:sapphire laser in quasi-cw mode undergoes polarization control (Pol) before it is imaged into the sample using a 15 mm focal-length aspheric lens. The output is imaged via a 14 × telescope onto a variable slit, which collectively measures the total intensity output from the system, bath or all the waveguides using a large-area power-meter (PM). Alternatively, the output can be imaged onto a CCD camera for alignment and diagnostics. (c) CCD images of the output after 15 cm when illuminated at λ0=792.5 nm and at 830 nm. As designed, the light in the system waveguides is evenly distributed at λ0 apart from the target site, which is dark. In contrast, the target site is much brighter at 830 nm, indicating that more light will couple into the sink—a sign of ENAQT.

Mentions: On the basis of measurements of couplings and propagation constants in isolated pairs of waveguides (see Methods xsection), we selected the following design parameters: Δβ=C=1.0 cm−1, Ctrap=1.5 cm−1, and Csink=1.75 cm−1 (Fig. 1c). Figure 2a shows numerical modelling of light propagation given these parameters. Although these were designed for a center wavelength of 800 nm, variations in the implementation of the waveguide parameters resulted in equation 6 being satisfied at λ0=792.5 nm.


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)

Experimental setup and waveguide design.(a) Predicted dynamics of light in our waveguide array, as a function of z. The inset shows the predicted device output distribution for input at wavelength λ0. The sink array is sufficiently long that light reflecting from the far boundary fails to couple back into the system waveguides during the simulation. (b) A fibre-coupled, tunable Ti:sapphire laser in quasi-cw mode undergoes polarization control (Pol) before it is imaged into the sample using a 15 mm focal-length aspheric lens. The output is imaged via a 14 × telescope onto a variable slit, which collectively measures the total intensity output from the system, bath or all the waveguides using a large-area power-meter (PM). Alternatively, the output can be imaged onto a CCD camera for alignment and diagnostics. (c) CCD images of the output after 15 cm when illuminated at λ0=792.5 nm and at 830 nm. As designed, the light in the system waveguides is evenly distributed at λ0 apart from the target site, which is dark. In contrast, the target site is much brighter at 830 nm, indicating that more light will couple into the sink—a sign of ENAQT.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Experimental setup and waveguide design.(a) Predicted dynamics of light in our waveguide array, as a function of z. The inset shows the predicted device output distribution for input at wavelength λ0. The sink array is sufficiently long that light reflecting from the far boundary fails to couple back into the system waveguides during the simulation. (b) A fibre-coupled, tunable Ti:sapphire laser in quasi-cw mode undergoes polarization control (Pol) before it is imaged into the sample using a 15 mm focal-length aspheric lens. The output is imaged via a 14 × telescope onto a variable slit, which collectively measures the total intensity output from the system, bath or all the waveguides using a large-area power-meter (PM). Alternatively, the output can be imaged onto a CCD camera for alignment and diagnostics. (c) CCD images of the output after 15 cm when illuminated at λ0=792.5 nm and at 830 nm. As designed, the light in the system waveguides is evenly distributed at λ0 apart from the target site, which is dark. In contrast, the target site is much brighter at 830 nm, indicating that more light will couple into the sink—a sign of ENAQT.
Mentions: On the basis of measurements of couplings and propagation constants in isolated pairs of waveguides (see Methods xsection), we selected the following design parameters: Δβ=C=1.0 cm−1, Ctrap=1.5 cm−1, and Csink=1.75 cm−1 (Fig. 1c). Figure 2a shows numerical modelling of light propagation given these parameters. Although these were designed for a center wavelength of 800 nm, variations in the implementation of the waveguide parameters resulted in equation 6 being satisfied at λ0=792.5 nm.

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.