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Cited by 117Random lasers and scattering mediaQuantum Mechanics and ApplicationsQuantum chaos and dynamical systems

Enhancing coherent transport in a photonic network using controllable decoherence

Open access
Biggerstaff, Devon N., Heilmann, René, Zecevik, Aidan A., Gräfe, Markus, Broome, Matthew A., Fedrizzi, Alessandro, Nolte, Stefan, Szameit, Alexander +2 more·2016·Nature Communications
DOI 10.1038/ncomms11282PMC PMC4835546
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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.

AI snapshot

Written from the paper’s full text.

TL;DR

The paper reports an experimental photonic simulation of environment-assisted quantum transport (ENAQT) in a laser-written four-waveguide network, where decoherence is controlled by broadening the input illumination bandwidth. Broadband illumination produced a significant transport-efficiency enhancement, with the highest ENAQT of (7.6±1.2)% at 95 nm bandwidth.

Key findings

  • The authors demonstrate the first implementation of ENAQT, showing that coherent transport in a coupled, statically disordered system can be enhanced through decoherence.
  • The highest observed ENAQT was (7.6±1.2)% at a bandwidth of 95 nm; in this model the efficiency increases monotonically with decoherence strength, so there is no optimal level of decoherence.
  • At the central wavelength λ0=792.5 nm, one eigenstate of the simulated Hamiltonian has no support on target site 3, giving a maximum infinite-time trapping efficiency of 2/3; off-centre wavelengths increase efficiency above 2/3.
  • The theoretical prediction contains no free parameters and simulates dynamics under the target Hamiltonian with trapping from site 3 and pure dephasing between waveguide 4 and the other three waveguides.

Methods

  • Waveguides were fabricated in high-purity fused silica (Corning 7980) by femtosecond-laser direct writing using 150 fs, 400 μJ, 800 nm pulses at 100 kHz, focused 400 μm below the surface with a ×40 objective and translated at 75 mm min−1 (except waveguide 4). Couplings were determined from isolated waveguide pairs.
  • The four-site network used waveguide 1 as input, waveguide 3 as target, and a long tightly coupled linear waveguide array as sink. Design parameters were Δβ=C=1.0 cm−1, Ctrap=1.5 cm−1, and Csink=1.75 cm−1; although designed for 800 nm, equation (6) was satisfied at λ0=792.5 nm.
  • Decoherence was simulated by averaging over many optical wavelengths using broadband illumination and a wavelength-insensitive output measurement. Efficiency was measured as the fraction of light output in the sink modes using narrowband (<1 nm bandwidth, horizontally polarized, quasi-cw) light from a tunable Ti:sapphire laser over 745–835 nm, with output imaged by a 14× telescope and power measured after isolating system or sink waveguides with a variable slit.

Limitations

  • The paper states that the magnitude of ENAQT was limited by the maximum achievable decoherence, γ=0.02 cm−1, which was small compared with the inverse propagation length; it was limited by laser tunability (Δλ) and by Δβ being constrained via equation (6) to keep C small enough for the tight-binding approximation. These are stated as not fundamental limitations.
  • The paper states that theory–experiment disagreement is small considering factors including off-diagonal decoherence from coupled waveguides, non-perfectly exponential trapping, errors in coupling constants, optical losses, and error in satisfying equation (6); the shaded band represents error if Δβ(λ0) deviated from C(λ0) by up to 10%. Measurement uncertainty was about 8%, with day-to-day writing variability, and x=0.86 meant the decay was not perfectly exponential though effectively irreversible.
  • Evident from the text: the experimental demonstration is for a single four-site statically disordered network and the best fabricated sample; no other network sizes, materials, or device realizations are experimentally tested.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1038/ncomms11282

Cites

57 of 57 references verified0 citation errors · 0 not checkable

Statistics

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Claims the paper makes

0 of 18 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    We report an experimental simulation of environment-assisted coherent transport using an engineered network of laser-written waveguides.

    “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.”
    Quote in the paperSubstantial claim
  • Findingown data

    The highest ENAQT observed was (7.6±1.2)% at a bandwidth of 95 nm.

    “The highest ENAQT observed was (7.6±1.2)% at a bandwidth of 95 nm.”
    Quote in the paperSubstantial claim
  • Findingown data

    The magnitude of ENAQT was limited by the maximum achievable decoherence, which at γ=0.02 cm−1 was small compared with the inverse of the propagation length.

    “In our experiment, the magnitude of ENAQT was limited by the maximum achievable decoherence, which at γ=0.02 cm−1 was small compared with the inverse of the propagation length.”
    Quote in the paperSubstantial claim
  • Findingown data

    The output distribution shows a significant difference between illumination at λ0 and an off-centre wavelength.

    “Examples of the output distribution are given in Fig. 2c, showing the significant difference between illumination at λ0 and an off-centre wavelength.”
    Quote in the paperNot a substantial claim
  • Findingown data

    Angles of 120° between the plane and the other system waveguides minimize non-neighbour coupling.

    “Waveguide 3 and the sink waveguides are in a plane parallel to the surface, while angles of 120° between this plane and the other system waveguides minimize non-neighbour coupling.”
    Quote in the paperSubstantial claim
  • May combine two claims. 17
  • Classified as probably not a substantial claim. 17
  • The quote only partly states this claim. 1

  • May combine two claims.

    Findingown data

    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.

    “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.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    At the central simulation wavelength λ0, one of the eigenstates of H has no support on site 3, while the remaining three eigenstates all have substantial support on site 3.

    “In this case, one of the eigenstates of H has no support on site 3, , while the remaining three eigenstates all have substantial support on site 3.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The theoretical simulation models decoherence as pure dephasing between waveguide 4 and the other three waveguides at rate γ.

  • Classified as probably not a substantial claim.

    Findingown data

    The measured efficiency (fraction of light output in the sink modes) for wavelengths ranging from 745 to 835 nm.

    “Figure 3a shows the measured efficiency (fraction of light output in the sink modes) for wavelengths ranging from 745 to 835 nm.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    Unlike in other examples of ENAQT, the efficiency increases monotonically with the strength of decoherence, meaning there is no optimal level of decoherence in this model.

    “Unlike in other examples of ENAQT5, the efficiency increases monotonically with the strength of decoherence, meaning there is no optimal level of decoherence in this model.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [5] Rebentrost, P., Mohseni, M., Kassal, I., Lloyd, S. & Aspuru-Guzik, A. Environment-assisted quantum transport. New J. Phys. 11, 033003 (2009). source

      Not checked in the free run.

    • The authors state this as an assumption: The theoretical simulation models decoherence as pure dephasing between waveguide 4 and the other three waveguides at rate γ.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingreasoning

    In the best sample, the writing speed was decreased by 12%.

    “In the best sample, the writing speed was decreased by 12%.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingcitation

    The system-sink population transfer can be modelled as a constant effective rate if x=... In our case, although x=0.86 meant the decay was not perfectly exponential, it was nevertheless effectively irreversible.

    “The system-sink population transfer can be modelled as a constant effective rate43 if . In our case, although x=0.86 meant that the decay was not perfectly exponential, it was nevertheless effectively irreversible, considering that sufficiently many sink modes were present to prevent reflection from the far end and back into the main waveguides.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [43] Longhi, S. Nonexponential decay via tunneling in tight-binding lattices and the optical Zeno effect. Phys. Rev. Lett. 97, 110402 (2006). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Variations in the implementation of the waveguide parameters resulted in equation 6 being satisfied at λ0=792.5 nm.

    “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.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning

    We were limited by the tunability of our laser (Δλ) and by the need to keep C small enough to stay in the tight-binding approximation.

    “We were limited by two components of equation (4): the tunability of our laser limited Δλ, while Δβ was limited (via equation (6)) by the need to keep C small enough to stay in the tight-binding approximation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    At other wavelengths, the eigenstate will have some support on waveguide 3 and thus be able to couple to the sink, increasing the efficiency above 2/3.

    “At other wavelengths, will have some support on waveguide 3 and thus be able to couple to the sink, increasing the efficiency above 2/3, as shown in Fig. 1d.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The theoretical simulation models decoherence as pure dephasing between waveguide 4 and the other three waveguides at rate γ.

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Findingreasoning

    The disagreement between theory and experiment is small considering the number of possible contributing factors.

    “The disagreement between theory and experiment is small considering the number of possible contributing factors.”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: The theoretical simulation models decoherence as pure dephasing between waveguide 4 and the other three waveguides at rate γ.

  • May combine two claims. The quote only partly states this claim.

    Findingreasoning

    Because the eigenstate cannot couple to the sink at λ0, the maximum trapping efficiency at infinite time is 2/3.

    “Because cannot couple to the sink—at least at λ0—the maximum trapping efficiency at infinite time is .”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The theoretical simulation models decoherence as pure dephasing between waveguide 4 and the other three waveguides at rate γ.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingreasoning

    Permanent index changes result in elliptical, vertically oriented, single-mode waveguides with modes ∼17 × 19 μm in size at 800 nm.

    “Permanent index changes result in the focus, yielding elliptical, vertically oriented, single-mode waveguides with modes ∼17 × 19 μm in size at 800 nm.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    ENAQT can occur on an ordered lattice where all the energies are equal.

    “Although ENAQT can occur on an ordered lattice where all the energies ɛm are equal21, transport enhancement was first explained in disordered systems, which we consider here.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [21] Kassal, I. & Aspuru-Guzik, A. Environment-assisted quantum transport in ordered systems. New J. Phys. 14, 053041 (2012). source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    Integrated optics is suitable for simulating specific target Hamiltonians as well as open quantum systems with controllable loss and decoherence.

    “We show integrated optics to be suitable for simulating specific target Hamiltonians as well as open quantum systems with controllable loss and decoherence.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisenone given

    ENAQT is about the efficiency of transport from a particular initial site to a particular target site, where the excitation is irreversibly trapped.

    “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.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisecitation

    It has been predicted that the efficiency of coherent transport can be enhanced through dynamic interaction between the system and a noisy environment.

    “It has been predicted that the efficiency of coherent transport can be enhanced through dynamic interaction between the system and a noisy environment.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [5] Rebentrost, P., Mohseni, M., Kassal, I., Lloyd, S. & Aspuru-Guzik, A. Environment-assisted quantum transport. New J. Phys. 11, 033003 (2009). source

      Not checked in the free run.

    • cites [6] Plenio, M. B. & Huelga, S. F. Dephasing-assisted transport: quantum networks and biomolecules. New J. Phys. 10, 113019 (2008). source

      Not checked in the free run.

    • cites [7] Chin, A., Datta, A., Caruso, F., Huelga, S. & Plenio, M. Noise-assisted energy transfer in quantum networks and light-harvesting complexes. New J. Phys. 12, 065002 (2010). source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisenone given

    Trapping can be modelled as irreversible coupling of the target site to a sink at rate κ.

    “It can be modelled as irreversible coupling of the target site to a sink at rate κ.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S1 (asserted).

    Premisereasoning

    Increasing fluctuations enhance site-to-site transfer by bringing neighbouring sites into transient resonance more frequently.

    “On that view, increasing fluctuations enhance site-to-site transfer by bringing neighbouring sites into transient resonance more frequently.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    Integrated photonics is well-suited for simulating open quantum systems and capable of implementing a disordered target Hamiltonian with controllable loss.

    “Our results demonstrate that integrated photonics is well-suited for simulating open quantum systems and capable of implementing a disordered target Hamiltonian with controllable loss.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisereasoning

    Adding decoherence diminishes these coherent processes, increasing the transport efficiency to the target.

    “Adding decoherence diminishes these coherent processes, increasing the transport efficiency to the target.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisereasoning

    The resulting decoherence will not only have characteristics of pure dephasing but will also include off-diagonal terms.

    “The resulting decoherence will therefore not only have characteristics of pure dephasing (as in equation (3)), but will also include off-diagonal terms.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based).

    Interpretationnone given

    Analogies with and extensions of our approach will aid in the experimental optimization of transport in other engineered quantum systems.

    “In addition, analogies with and extensions of our approach will aid in the experimental optimization of transport in other engineered quantum systems.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisenone given

    The intrinsic stability of laser-written waveguide arrays renders decoherence challenging to simulate.

    “The intrinsic stability of laser-written waveguide arrays renders decoherence challenging to simulate.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing), S4 (based).

    Premisenone given

    Decoherence-if it is in the site basis-can be modelled as fluctuations of site energies.

    “The second view is that decoherence—if it is in the site basis, as is often assumed—can be modelled as fluctuations of site energies.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisereasoning

    The eigenstates of H are stationary in the absence of decoherence, making it difficult to reach the target if the initial and target sites differ in energy.

    “The third approach is to note that the eigenstates of H are stationary in the absence of decoherence, making it difficult to reach the target if the initial and target sites differ in energy.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Premisenone given

    We chose the network of four sites because it is one of the smallest systems in which ENAQT is possible and because it can give significant enhancements even with relatively weak decoherence.

    “For our simulation, we chose the network of four sites shown in Fig. 1b because it is one of the smallest systems in which ENAQT is possible and because it can give significant enhancements even with relatively weak decoherence.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisereasoning

    The overall strength γ of the decoherence can be quantified as the inverse of the optical coherence length, and is usually proportional to the full-width at half-maximum bandwidth Δλ.

    “The overall strength γ of the decoherence can be quantified as the inverse of the optical coherence length, , and is usually proportional to the full-width at half-maximum bandwidth Δλ.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisereasoning

    ENAQT can be understood as suppression of destructive interferences, as bringing of neighbouring sites into resonance, or as transitions between otherwise-stationary eigenstates.

    “ENAQT can be understood in several different ways: as suppression of destructive interferences, as bringing of neighbouring sites into resonance, or as transitions between otherwise-stationary eigenstates.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Off-diagonal terms imply that our decoherence could be used to simulate ENAQT in ordered systems, but the effect would be weaker because of the absence of the pure-dephasing contribution when Δβ=0.

    “Indeed, the off-diagonal terms imply that our decoherence could, in principle, be used to simulate ENAQT in ordered systems21, but the effect would be weaker because of the absence of the pure-dephasing contribution when Δβ=0.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [21] Kassal, I. & Aspuru-Guzik, A. Environment-assisted quantum transport in ordered systems. New J. Phys. 14, 053041 (2012). source

      Not checked in the free run.

  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationreasoning

    These are not fundamental limitations, and future improvements that increase γ would result in significantly larger transport enhancement.

    “These are not fundamental limitations, and future improvements that increase γ would result in significantly larger transport enhancement;”
    Quote in the paperSubstantial claim
30 of 30

  • The authors state this as an assumption.

    The theoretical simulation models decoherence as pure dephasing between waveguide 4 and the other three waveguides at rate γ.

    “It is a simulation of the dynamics under the simulated Hamiltonian H, together with trapping from site 3 at the rate κ, discussed in Methods section, and pure dephasing between waveguide 4 and the other three waveguides at the rate γ.”
1 of 1

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Direct laser-written waveguides offer the possibility of implementing complex lattice geometries including the third spatial dimension, and consequently of utilization for investigating systems beyond the standard model, in quantum biophysics, and in quantum artificial life.

    “Special attention is paid to direct laser-written waveguides since they offer the possibility of implementing complex lattice geometries including the third spatial dimension [129, 130], and consequently of utilization for investigating systems beyond the standard model [131], in quantum biophysics [132-134], and in quantum artificial life [135,136].”

    From Integrated photonic quantum walks (2020) · cites this paper as [134]

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Related

Authors
Biggerstaff, D. N., Heilmann, R., Zecevik, A. A., Gräfe, M., Broome, M. A., Fedrizzi, A., Nolte, S., Szameit, A., White, A. G., & Kassal, I.
Affiliations
  • The University of Queensland (AU)
  • Friedrich Schiller University Jena (DE)
Corresponding author
Kassal, Ivan
ORCID
Venue
Nature Communications
Publisher
Springer Science and Business Media LLC
Published
2016-04-15
Volume
7
Issue
1
Pages
11282-11282
ISSN
2041-1723 (ISSN-L)
DOI
10.1038/ncomms11282
PMC
PMC4835546
OpenAlex
W291061745
Semantic Scholar
e51fe9224df9e4592d26d516c8aa907b0e2f7392
Cited by
117
References
57
Citations by year
2026: 8 · 2025: 6 · 2024: 9 · 2023: 9 · 2022: 16 · 2021: 13 · 2020: 8 · 2019: 13 · 2018: 15 · 2017: 12 · 2016: 6 · 2015: 2
FWCI
5.47
Type
journal article
Language
en
Open access
Licence
Locations
  • Nature Communications (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Warwick Research Archive Portal (University of Warwick) (acceptedVersion)
  • TUbilio (Technical University of Darmstadt) (acceptedVersion)
  • Technischen Universität Darmstadt (acceptedVersion, cc-by)
  • arXiv (Cornell University) (submittedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Technischen Universität Darmstadt (submittedVersion)
  • arXiv (Cornell University)
  • Technischen Universität Darmstadt (cc-by)
Funders
  • Deutsche Forschungsgemeinschaft (NO462/6-1, SZ 276/9‐1, SZ276/7-1)
  • German-Israeli Foundation for Scientific Research and Development (1157-127.14/2011)
Topics
  • Physical Sciences › Physics and Astronomy › Acoustics and Ultrasonics › Random lasers and scattering media
  • Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Quantum Mechanics and Applications
  • Physical Sciences › Physics and Astronomy › Statistical and Nonlinear Physics › Quantum chaos and dynamical systems
Keywords
decoherence, optical networks, integrated photonics, laser-written waveguides, open quantum systems, Hamiltonian simulation, transport efficiency

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