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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

Magnitude of observed ENAQT.(a) Transport efficiency—the portion of light that makes it to the sink—as a function of wavelength. The minimum efficiency at λ0=792.5 nm is η=0.636±0.002, slightly less than the theoretical infinite time limit of 2/3. The error bars are s.d. caused by imperfect repeatability in coupling light into the sample and laser power fluctuations. (b) ENAQT—the relative increase in the efficiency over that at λ0—as a function of the optical bandwidth (top horizontal axis) and corresponding decoherence strength γ (bottom horizontal axis). The red points are obtained by averaging the measured efficiencies over a uniform broadband spectrum with width Δλ and centred at λ0. The blue line represents the theoretical ENAQT, calculated based on the model in Fig. 1b and containing no free parameters (it is the cross-section of Fig. 1d along the red line segment). The shaded region represents possible ENAQT if Δβ(λ0) deviates from C(λ0) by up to 10%.
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f3: Magnitude of observed ENAQT.(a) Transport efficiency—the portion of light that makes it to the sink—as a function of wavelength. The minimum efficiency at λ0=792.5 nm is η=0.636±0.002, slightly less than the theoretical infinite time limit of 2/3. The error bars are s.d. caused by imperfect repeatability in coupling light into the sample and laser power fluctuations. (b) ENAQT—the relative increase in the efficiency over that at λ0—as a function of the optical bandwidth (top horizontal axis) and corresponding decoherence strength γ (bottom horizontal axis). The red points are obtained by averaging the measured efficiencies over a uniform broadband spectrum with width Δλ and centred at λ0. The blue line represents the theoretical ENAQT, calculated based on the model in Fig. 1b and containing no free parameters (it is the cross-section of Fig. 1d along the red line segment). The shaded region represents possible ENAQT if Δβ(λ0) deviates from C(λ0) by up to 10%.

Mentions: Our experimental setup is shown in Fig. 2b. We measured the efficiency using narrowband light (less than 1 nm bandwidth and always horizontally polarized for consistency) from a tunable Ti:sapphire laser (Spectra-Physics Tsunami) in quasi-cw mode (Fig. 2b). The output was imaged using a custom-built 14 × magnifying telescope and the optical power was measured using a large-area power-meter after isolating either the system or sink waveguides using a variable slit. Examples of the output distribution are given in Fig. 2c, showing the significant difference between illumination at λ0 and an off-centre wavelength. Figure 3a shows the measured efficiency (fraction of light output in the sink modes) for wavelengths ranging from 745 to 835 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)

Magnitude of observed ENAQT.(a) Transport efficiency—the portion of light that makes it to the sink—as a function of wavelength. The minimum efficiency at λ0=792.5 nm is η=0.636±0.002, slightly less than the theoretical infinite time limit of 2/3. The error bars are s.d. caused by imperfect repeatability in coupling light into the sample and laser power fluctuations. (b) ENAQT—the relative increase in the efficiency over that at λ0—as a function of the optical bandwidth (top horizontal axis) and corresponding decoherence strength γ (bottom horizontal axis). The red points are obtained by averaging the measured efficiencies over a uniform broadband spectrum with width Δλ and centred at λ0. The blue line represents the theoretical ENAQT, calculated based on the model in Fig. 1b and containing no free parameters (it is the cross-section of Fig. 1d along the red line segment). The shaded region represents possible ENAQT if Δβ(λ0) deviates from C(λ0) by up to 10%.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: Magnitude of observed ENAQT.(a) Transport efficiency—the portion of light that makes it to the sink—as a function of wavelength. The minimum efficiency at λ0=792.5 nm is η=0.636±0.002, slightly less than the theoretical infinite time limit of 2/3. The error bars are s.d. caused by imperfect repeatability in coupling light into the sample and laser power fluctuations. (b) ENAQT—the relative increase in the efficiency over that at λ0—as a function of the optical bandwidth (top horizontal axis) and corresponding decoherence strength γ (bottom horizontal axis). The red points are obtained by averaging the measured efficiencies over a uniform broadband spectrum with width Δλ and centred at λ0. The blue line represents the theoretical ENAQT, calculated based on the model in Fig. 1b and containing no free parameters (it is the cross-section of Fig. 1d along the red line segment). The shaded region represents possible ENAQT if Δβ(λ0) deviates from C(λ0) by up to 10%.
Mentions: Our experimental setup is shown in Fig. 2b. We measured the efficiency using narrowband light (less than 1 nm bandwidth and always horizontally polarized for consistency) from a tunable Ti:sapphire laser (Spectra-Physics Tsunami) in quasi-cw mode (Fig. 2b). The output was imaged using a custom-built 14 × magnifying telescope and the optical power was measured using a large-area power-meter after isolating either the system or sink waveguides using a variable slit. Examples of the output distribution are given in Fig. 2c, showing the significant difference between illumination at λ0 and an off-centre wavelength. Figure 3a shows the measured efficiency (fraction of light output in the sink modes) for wavelengths ranging from 745 to 835 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.


Related in: MedlinePlus