13.
E-P Yao, B J Bohn, Y Tong, H Huang, L Polavarapu, J Feldmann
Exciton Diffusion Lengths and Dissociation Rates in CsPbBr3 Nanocrystal–Fullerene Composites: Layer-by-Layer versus Blend Structures Journal Article
In: Advanced Optical Materials, vol. 7, no. 8, pp. 1801776, 2019, ISSN: 2195-1071.
@article{,
title = {Exciton Diffusion Lengths and Dissociation Rates in CsPbBr3 Nanocrystal\textendashFullerene Composites: Layer-by-Layer versus Blend Structures},
author = {E-P Yao and B J Bohn and Y Tong and H Huang and L Polavarapu and J Feldmann},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.201801776},
doi = {10.1002/adom.201801776},
issn = {2195-1071},
year = {2019},
date = {2019-02-18},
journal = {Advanced Optical Materials},
volume = {7},
number = {8},
pages = {1801776},
abstract = {Abstract Solution-processable perovskite nanocrystals (NCs) are gaining increasing interest in the field of photovoltaics because of their enhanced stability compared to their thin-film counterparts. However, the charge transfer dynamics in perovskite NC based light-harvesting systems are not well understood. By applying femtosecond differential transmission (DT) spectroscopy the photoinduced charge transfer from inorganic perovskite CsPbBr3 NCs to the fullerene derivative phenyl-C61-butyric acid methyl ester (PCBM) is investigated for two fundamentally different architectures, namely layer-by-layer heterostructures and blend structures. By varying the thickness of the NC layer on top of the PCBM in the layer-by-layer heterostructure, an exciton diffusion length of 290 ± 28 nm for CsPbBr3 NC is extracted. The diffusion process is followed by an ultrafast exciton dissociation (within 200 fs) at the CsPbBr3 NC/PCBM interface. In blend structures an overall faster charge transfer process is observed. Furthermore, photoconductivity measurements on a blend structure-based photodetector reveal an effective charge extraction from the active layer resulting in a high photosensitivity. DT measurements on this blend structure including adjacent electron- or hole-transport layers give insight into the extraction process and suggest a certain degree of phase segregation, which assists the charge collection.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Solution-processable perovskite nanocrystals (NCs) are gaining increasing interest in the field of photovoltaics because of their enhanced stability compared to their thin-film counterparts. However, the charge transfer dynamics in perovskite NC based light-harvesting systems are not well understood. By applying femtosecond differential transmission (DT) spectroscopy the photoinduced charge transfer from inorganic perovskite CsPbBr3 NCs to the fullerene derivative phenyl-C61-butyric acid methyl ester (PCBM) is investigated for two fundamentally different architectures, namely layer-by-layer heterostructures and blend structures. By varying the thickness of the NC layer on top of the PCBM in the layer-by-layer heterostructure, an exciton diffusion length of 290 ± 28 nm for CsPbBr3 NC is extracted. The diffusion process is followed by an ultrafast exciton dissociation (within 200 fs) at the CsPbBr3 NC/PCBM interface. In blend structures an overall faster charge transfer process is observed. Furthermore, photoconductivity measurements on a blend structure-based photodetector reveal an effective charge extraction from the active layer resulting in a high photosensitivity. DT measurements on this blend structure including adjacent electron- or hole-transport layers give insight into the extraction process and suggest a certain degree of phase segregation, which assists the charge collection.
12.
P Zimmermann, A Hötger, N Fernandez, A Nolinder, K Müller, J J Finley, A W Holleitner
Toward Plasmonic Tunnel Gaps for Nanoscale Photoemission Currents by On-Chip Laser Ablation Journal Article
In: Nano Letters, vol. 19, no. 2, pp. 1172-1178, 2019, ISSN: 1530-6984.
@article{,
title = {Toward Plasmonic Tunnel Gaps for Nanoscale Photoemission Currents by On-Chip Laser Ablation},
author = {P Zimmermann and A H\"{o}tger and N Fernandez and A Nolinder and K M\"{u}ller and J J Finley and A W Holleitner},
url = {https://doi.org/10.1021/acs.nanolett.8b04612},
doi = {10.1021/acs.nanolett.8b04612},
issn = {1530-6984},
year = {2019},
date = {2019-02-13},
journal = {Nano Letters},
volume = {19},
number = {2},
pages = {1172-1178},
abstract = {We demonstrate that prestructured metal nanogaps can be shaped on-chip to below 10 nm by femtosecond laser ablation. We explore the plasmonic properties and the nonlinear photocurrent characteristics of the formed tunnel junctions. The photocurrent can be tuned from multiphoton absorption toward the laser-induced strong-field tunneling regime in the nanogaps. We demonstrate that a unipolar ballistic electron current is achieved by designing the plasmonic junctions to be asymmetric, which allows ultrafast electronics on the nanometer scale.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We demonstrate that prestructured metal nanogaps can be shaped on-chip to below 10 nm by femtosecond laser ablation. We explore the plasmonic properties and the nonlinear photocurrent characteristics of the formed tunnel junctions. The photocurrent can be tuned from multiphoton absorption toward the laser-induced strong-field tunneling regime in the nanogaps. We demonstrate that a unipolar ballistic electron current is achieved by designing the plasmonic junctions to be asymmetric, which allows ultrafast electronics on the nanometer scale.
11.
P Zimmermann, A Hötger, N Fernandez, A Nolinder, K Müller, J J Finley, A W Holleitner
Toward Plasmonic Tunnel Gaps for Nanoscale Photoemission Currents by On-Chip Laser Ablation Journal Article
In: Nano Letters, vol. 19, no. 2, pp. 1172-1178, 2019, ISSN: 1530-6984.
@article{,
title = {Toward Plasmonic Tunnel Gaps for Nanoscale Photoemission Currents by On-Chip Laser Ablation},
author = {P Zimmermann and A H\"{o}tger and N Fernandez and A Nolinder and K M\"{u}ller and J J Finley and A W Holleitner},
url = {https://doi.org/10.1021/acs.nanolett.8b04612},
doi = {10.1021/acs.nanolett.8b04612},
issn = {1530-6984},
year = {2019},
date = {2019-02-13},
journal = {Nano Letters},
volume = {19},
number = {2},
pages = {1172-1178},
abstract = {We demonstrate that prestructured metal nanogaps can be shaped on-chip to below 10 nm by femtosecond laser ablation. We explore the plasmonic properties and the nonlinear photocurrent characteristics of the formed tunnel junctions. The photocurrent can be tuned from multiphoton absorption toward the laser-induced strong-field tunneling regime in the nanogaps. We demonstrate that a unipolar ballistic electron current is achieved by designing the plasmonic junctions to be asymmetric, which allows ultrafast electronics on the nanometer scale.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We demonstrate that prestructured metal nanogaps can be shaped on-chip to below 10 nm by femtosecond laser ablation. We explore the plasmonic properties and the nonlinear photocurrent characteristics of the formed tunnel junctions. The photocurrent can be tuned from multiphoton absorption toward the laser-induced strong-field tunneling regime in the nanogaps. We demonstrate that a unipolar ballistic electron current is achieved by designing the plasmonic junctions to be asymmetric, which allows ultrafast electronics on the nanometer scale.
10.
T Schröder, M B Scheible, F Steiner, J Vogelsang, P Tinnefeld
Interchromophoric Interactions Determine the Maximum Brightness Density in DNA Origami Structures Journal Article
In: Nano Letters, vol. 19, no. 2, pp. 1275-1281, 2019, ISSN: 1530-6984.
@article{,
title = {Interchromophoric Interactions Determine the Maximum Brightness Density in DNA Origami Structures},
author = {T Schr\"{o}der and M B Scheible and F Steiner and J Vogelsang and P Tinnefeld},
url = {https://doi.org/10.1021/acs.nanolett.8b04845},
doi = {10.1021/acs.nanolett.8b04845},
issn = {1530-6984},
year = {2019},
date = {2019-02-13},
urldate = {2019-02-13},
journal = {Nano Letters},
volume = {19},
number = {2},
pages = {1275-1281},
abstract = {An ideal point light source is as small and as bright as possible. For fluorescent point light sources, homogeneity of the light sources is important as well as that the fluorescent units inside the light source maintain their photophysical properties, which is compromised by dye aggregation. Here we propose DNA origami as a rigid scaffold to arrange dye molecules in a dense pixel array with high control of stoichiometry and dye\textendashdye interactions. In order to find the highest labeling density in a DNA origami structure without influencing dye photophysics, we alter the distance of two ATTO647N dyes in single base pair steps and probe the dye\textendashdye interactions on the single-molecule level. For small distances strong quenching in terms of intensity and fluorescence lifetime is observed. With increasing distance, we observe reduced quenching and molecular dynamics. However, energy transfer processes in the weak coupling regime still have a significant impact and can lead to quenching by singlet-dark-state-annihilation. Our study fills a gap of studying the interactions of dyes relevant for superresolution microscopy with dense labeling and for single-molecule biophysics. Incorporating these findings in a 3D DNA origami object will pave the way to bright and homogeneous DNA origami nanobeads.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
An ideal point light source is as small and as bright as possible. For fluorescent point light sources, homogeneity of the light sources is important as well as that the fluorescent units inside the light source maintain their photophysical properties, which is compromised by dye aggregation. Here we propose DNA origami as a rigid scaffold to arrange dye molecules in a dense pixel array with high control of stoichiometry and dye–dye interactions. In order to find the highest labeling density in a DNA origami structure without influencing dye photophysics, we alter the distance of two ATTO647N dyes in single base pair steps and probe the dye–dye interactions on the single-molecule level. For small distances strong quenching in terms of intensity and fluorescence lifetime is observed. With increasing distance, we observe reduced quenching and molecular dynamics. However, energy transfer processes in the weak coupling regime still have a significant impact and can lead to quenching by singlet-dark-state-annihilation. Our study fills a gap of studying the interactions of dyes relevant for superresolution microscopy with dense labeling and for single-molecule biophysics. Incorporating these findings in a 3D DNA origami object will pave the way to bright and homogeneous DNA origami nanobeads.
9.
J Fichtner, B Garlyyev, S Watzele, H A El-Sayed, J N Schwämmlein, W-J Li, F M Maillard, L Dubau, J Michalička, J M Macak, A W Holleitner, A S Bandarenka
Top-Down Synthesis of Nanostructured Platinum–Lanthanide Alloy Oxygen Reduction Reaction Catalysts: PtxPr/C as an Example Journal Article
In: ACS Applied Materials & Interfaces, vol. 11, no. 5, pp. 5129-5135, 2019, ISSN: 1944-8244.
@article{,
title = {Top-Down Synthesis of Nanostructured Platinum\textendashLanthanide Alloy Oxygen Reduction Reaction Catalysts: PtxPr/C as an Example},
author = {J Fichtner and B Garlyyev and S Watzele and H A El-Sayed and J N Schw\"{a}mmlein and W-J Li and F M Maillard and L Dubau and J Michali\v{c}ka and J M Macak and A W Holleitner and A S Bandarenka},
url = {https://doi.org/10.1021/acsami.8b20174},
doi = {10.1021/acsami.8b20174},
issn = {1944-8244},
year = {2019},
date = {2019-02-06},
journal = {ACS Applied Materials \& Interfaces},
volume = {11},
number = {5},
pages = {5129-5135},
abstract = {The oxygen reduction reaction (ORR) is of great interest for future sustainable energy conversion and storage, especially concerning fuel cell applications. The preparation of active, affordable, and scalable electrocatalysts and their application in fuel cell engines of hydrogen cars is a prominent step toward the reduction of air pollution, especially in urban areas. Alloying nanostructured Pt with lanthanides is a promising approach to enhance its catalytic ORR activity, whereby the development of a simple synthetic route turned out to be a nontrivial endeavor. Herein, for the first time, we present a successful single-step, scalable top-down synthetic route for Pt\textendashlanthanide alloy nanoparticles, as witnessed by the example of Pr-alloyed Pt nanoparticles. The catalyst was characterized by high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and photoelectron spectroscopy, and its electrocatalytic oxygen reduction activity was investigated using a rotating disk electrode technique. PtxPr/C showed ∼3.5 times higher [1.96 mA/cm2Pt, 0.9 V vs reversible hydrogen electrode (RHE)] specific activity and ∼1.7 times higher (0.7 A/mgPt, 0.9 V vs RHE) mass activity compared to commercial Pt/C catalysts. On the basis of previous findings and characterization of the PtxPr/C catalyst, the activity improvement over commercial Pt/C originates from a lattice strain introduced by the alloying process.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The oxygen reduction reaction (ORR) is of great interest for future sustainable energy conversion and storage, especially concerning fuel cell applications. The preparation of active, affordable, and scalable electrocatalysts and their application in fuel cell engines of hydrogen cars is a prominent step toward the reduction of air pollution, especially in urban areas. Alloying nanostructured Pt with lanthanides is a promising approach to enhance its catalytic ORR activity, whereby the development of a simple synthetic route turned out to be a nontrivial endeavor. Herein, for the first time, we present a successful single-step, scalable top-down synthetic route for Pt–lanthanide alloy nanoparticles, as witnessed by the example of Pr-alloyed Pt nanoparticles. The catalyst was characterized by high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and photoelectron spectroscopy, and its electrocatalytic oxygen reduction activity was investigated using a rotating disk electrode technique. PtxPr/C showed ∼3.5 times higher [1.96 mA/cm2Pt, 0.9 V vs reversible hydrogen electrode (RHE)] specific activity and ∼1.7 times higher (0.7 A/mgPt, 0.9 V vs RHE) mass activity compared to commercial Pt/C catalysts. On the basis of previous findings and characterization of the PtxPr/C catalyst, the activity improvement over commercial Pt/C originates from a lattice strain introduced by the alloying process.
8.
T Wu, Y Luo, S A Maier, L Wei
Phase-matching and Peak Nonlinearity Enhanced Third-Harmonic Generation in Graphene Plasmonic Coupler Journal Article
In: Physical Review Applied, vol. 11, no. 1, pp. 014049, 2019.
@article{,
title = {Phase-matching and Peak Nonlinearity Enhanced Third-Harmonic Generation in Graphene Plasmonic Coupler},
author = {T Wu and Y Luo and S A Maier and L Wei},
url = {https://link.aps.org/doi/10.1103/PhysRevApplied.11.014049},
doi = {10.1103/PhysRevApplied.11.014049},
year = {2019},
date = {2019-01-24},
journal = {Physical Review Applied},
volume = {11},
number = {1},
pages = {014049},
abstract = {Strong nonlinear optical effects generally require giant optical fields interacting with the nonlinear media. Doped graphene hosts electrically tunable plasmons with long lifetimes that interact strongly with light. We investigate a graphene plasmonic coupler and explore two mechanisms to pursue highly efficient third-harmonic generation (THG): (1) phase matching of graphene plasmons at fundamental- and third-harmonic frequencies and (2) peak third-order nonlinear susceptibility of doped graphene. The third-harmonic wave is mainly converted from the evanescent mode of the incident light and the THG efficiency is found to be enhanced by over 10 orders of magnitude compared with a bare monolayer graphene. The significantly enhanced nonlinear optical responses in the graphene plasmonic coupler make this configuration an ideal platform for the development of alternative frequency generators and for signal processing at midinfrared and terahertz frequencies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Strong nonlinear optical effects generally require giant optical fields interacting with the nonlinear media. Doped graphene hosts electrically tunable plasmons with long lifetimes that interact strongly with light. We investigate a graphene plasmonic coupler and explore two mechanisms to pursue highly efficient third-harmonic generation (THG): (1) phase matching of graphene plasmons at fundamental- and third-harmonic frequencies and (2) peak third-order nonlinear susceptibility of doped graphene. The third-harmonic wave is mainly converted from the evanescent mode of the incident light and the THG efficiency is found to be enhanced by over 10 orders of magnitude compared with a bare monolayer graphene. The significantly enhanced nonlinear optical responses in the graphene plasmonic coupler make this configuration an ideal platform for the development of alternative frequency generators and for signal processing at midinfrared and terahertz frequencies.
7.
J Li, E Tan, N Keller, Y-H Chen, P M Zehetmaier, A C Jakowetz, T Bein, P Knochel
Cobalt-Catalyzed Electrophilic Aminations with Anthranils: An Expedient Route to Condensed Quinolines Journal Article
In: Journal of the American Chemical Society, vol. 141, no. 1, pp. 98-103, 2019, ISSN: 0002-7863.
@article{,
title = {Cobalt-Catalyzed Electrophilic Aminations with Anthranils: An Expedient Route to Condensed Quinolines},
author = {J Li and E Tan and N Keller and Y-H Chen and P M Zehetmaier and A C Jakowetz and T Bein and P Knochel},
url = {https://doi.org/10.1021/jacs.8b11466},
doi = {10.1021/jacs.8b11466},
issn = {0002-7863},
year = {2019},
date = {2019-01-09},
journal = {Journal of the American Chemical Society},
volume = {141},
number = {1},
pages = {98-103},
abstract = {The reaction of various organozinc pivalates with anthranils provides anilines derivatives, which cyclize under acidic conditions providing condensed quinolines. Using alkenylzinc pivalates, electron-rich arylzinc pivalates or heterocyclic zinc pivalates produces directly the condensed quinolines of which several structures belong to new heterocyclic scaffolds. These N-heterocycles are of particular interest for organic light emitting diodes with their high photoluminescence quantum yields and long exciton lifetimes as well as for hole-transporting materials in methylammonium lead iodide perovskites solar cells due to an optimal band alignment for holes and a large bandgap.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The reaction of various organozinc pivalates with anthranils provides anilines derivatives, which cyclize under acidic conditions providing condensed quinolines. Using alkenylzinc pivalates, electron-rich arylzinc pivalates or heterocyclic zinc pivalates produces directly the condensed quinolines of which several structures belong to new heterocyclic scaffolds. These N-heterocycles are of particular interest for organic light emitting diodes with their high photoluminescence quantum yields and long exciton lifetimes as well as for hole-transporting materials in methylammonium lead iodide perovskites solar cells due to an optimal band alignment for holes and a large bandgap.
6.
M Rück, A S Bandarenka, F Calle-Vallejo, A Gagliardi
Oxygen Reduction Reaction: Rapid Prediction of Mass Activity of Nanostructured Platinum Electrocatalysts Journal Article
In: The Journal of Physical Chemistry Letters, vol. 9, no. 15, pp. 4463-4468, 2018.
@article{nokey,
title = {Oxygen Reduction Reaction: Rapid Prediction of Mass Activity of Nanostructured Platinum Electrocatalysts},
author = {M R\"{u}ck and A S Bandarenka and F Calle-Vallejo and A Gagliardi},
url = {https://doi.org/10.1021/acs.jpclett.8b01864},
doi = {10.1021/acs.jpclett.8b01864},
year = {2018},
date = {2018-07-20},
urldate = {2018-07-20},
journal = {The Journal of Physical Chemistry Letters},
volume = {9},
number = {15},
pages = {4463-4468},
abstract = {Tailored Pt nanoparticle catalysts are promising candidates to accelerate the oxygen reduction reaction (ORR) in fuel cells. However, the search for active nanoparticle catalysts is hindered by the laborious effort of experimental synthesis and measurements. On the other hand, density functional theory-based approaches are still time-consuming and often not efficient. In this study, we introduce a computational model which enables rapid catalytic activity calculation of unstrained pure Pt nanoparticle electrocatalysts. Regarding particle size effects on Pt nanoparticles, experimental catalytic mass activities from previous studies are accurately reproduced by our computational model. Moreover, beyond available experiments, our computational model identifies potential enhancement in mass activity up to 190% over the experimentally detected maximum. Importantly, the rapid activity calculation enabled by our computational model may pave the way for extensive nanoparticle screening to expedite the search for improved electrocatalysts.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Tailored Pt nanoparticle catalysts are promising candidates to accelerate the oxygen reduction reaction (ORR) in fuel cells. However, the search for active nanoparticle catalysts is hindered by the laborious effort of experimental synthesis and measurements. On the other hand, density functional theory-based approaches are still time-consuming and often not efficient. In this study, we introduce a computational model which enables rapid catalytic activity calculation of unstrained pure Pt nanoparticle electrocatalysts. Regarding particle size effects on Pt nanoparticles, experimental catalytic mass activities from previous studies are accurately reproduced by our computational model. Moreover, beyond available experiments, our computational model identifies potential enhancement in mass activity up to 190% over the experimentally detected maximum. Importantly, the rapid activity calculation enabled by our computational model may pave the way for extensive nanoparticle screening to expedite the search for improved electrocatalysts.
5.
A Kuhn, O Gerbig, C Zhu, F Falkenberg, J Maier, B V Lotsch
A new ultrafast superionic Li-conductor: ion dynamics in Li11Si2PS12 and comparison with other tetragonal LGPS-type electrolytes Journal Article
In: Physical Chemistry Chemical Physics, vol. 16, no. 28, pp. 14669-14674, 2014, ISSN: 1463-9076.
@article{nokey,
title = {A new ultrafast superionic Li-conductor: ion dynamics in Li11Si2PS12 and comparison with other tetragonal LGPS-type electrolytes},
author = {A Kuhn and O Gerbig and C Zhu and F Falkenberg and J Maier and B V Lotsch},
url = {http://dx.doi.org/10.1039/C4CP02046D},
doi = {10.1039/C4CP02046D},
issn = {1463-9076},
year = {2014},
date = {2014-05-23},
journal = {Physical Chemistry Chemical Physics},
volume = {16},
number = {28},
pages = {14669-14674},
abstract = {We report on a new ultrafast solid electrolyte of the composition Li11Si2PS12, which exhibits a higher room-temperature Li ion diffusivity than the present record holder Li10GeP2S12. We discuss the high-pressure synthesis and ion dynamics of tetragonal Li11Si2PS12, and comparison is made with our investigations of related members of the LMePS family, i.e. electrolytes of the general formula Li11−xMe2−xP1+xS12 with Me = Ge, Sn : Li10GeP2S12, Li7GePS8, Li10SnP2S12. The structure and dynamics were studied with multiple complementary techniques and the macroscopic diffusion could be traced back to fast Li ion hopping in the crystalline lattice. A clear correlation between the diffusivity and the unit cell volume of the LGPS-type electrolytes was observed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We report on a new ultrafast solid electrolyte of the composition Li11Si2PS12, which exhibits a higher room-temperature Li ion diffusivity than the present record holder Li10GeP2S12. We discuss the high-pressure synthesis and ion dynamics of tetragonal Li11Si2PS12, and comparison is made with our investigations of related members of the LMePS family, i.e. electrolytes of the general formula Li11−xMe2−xP1+xS12 with Me = Ge, Sn : Li10GeP2S12, Li7GePS8, Li10SnP2S12. The structure and dynamics were studied with multiple complementary techniques and the macroscopic diffusion could be traced back to fast Li ion hopping in the crystalline lattice. A clear correlation between the diffusivity and the unit cell volume of the LGPS-type electrolytes was observed.
4.
R Natālija, B Andreas, I Hristo, W Rafał
Sub-20-attosecond timing jitter from a mode-locked 200-MHz All-PM Er:NALM fiber laser Proceedings Article
In: Proc.SPIE, pp. 128650L, 0000.
@inproceedings{nokey,
title = {Sub-20-attosecond timing jitter from a mode-locked 200-MHz All-PM Er:NALM fiber laser},
author = {R Nat\={a}lija and B Andreas and I Hristo and W Rafa\l},
url = {https://doi.org/10.1117/12.2692373},
doi = {10.1117/12.2692373},
booktitle = {Proc.SPIE},
volume = {12865},
pages = {128650L},
abstract = {Our research team has achieved a significant milestone by generating pulses with sub-20-attosecond (as) timing jitter from a 200-MHz all-Polarization-Maintaining (PM) erbium-doped (Er:) Nonlinear Amplifying Loop Mirror (NALM) fiber laser. Accurate measurement of these temporal fluctuations was conducted using the Balanced Optical cross-Correlation (BOC) technique. Through comprehensive investigation, we identified the critical parameters responsible for timing jitter, including dispersion and pump power, and validated their impact. The fine-tuning of the contributing factors allowed us to demonstrate an exceptionally low integrated timing jitter of only 15.59 attoseconds, integrated from 10 kHz to 10 MHz. This accomplishment stands as the lowest value ever documented for any free-running mode-locked fiber lasers that are erbium-doped.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Our research team has achieved a significant milestone by generating pulses with sub-20-attosecond (as) timing jitter from a 200-MHz all-Polarization-Maintaining (PM) erbium-doped (Er:) Nonlinear Amplifying Loop Mirror (NALM) fiber laser. Accurate measurement of these temporal fluctuations was conducted using the Balanced Optical cross-Correlation (BOC) technique. Through comprehensive investigation, we identified the critical parameters responsible for timing jitter, including dispersion and pump power, and validated their impact. The fine-tuning of the contributing factors allowed us to demonstrate an exceptionally low integrated timing jitter of only 15.59 attoseconds, integrated from 10 kHz to 10 MHz. This accomplishment stands as the lowest value ever documented for any free-running mode-locked fiber lasers that are erbium-doped.
3.
R Ovcharenko, X Y Xu, B P Fingerhut
Scalable Distributed Memory Implementation of the Quasi-Adiabatic Propagator Path Integral Journal Article
In: Journal of Chemical Theory and Computation, 0000, ISSN: 1549-9618.
@article{nokey,
title = {Scalable Distributed Memory Implementation of the Quasi-Adiabatic Propagator Path Integral},
author = {R Ovcharenko and X Y Xu and B P Fingerhut},
url = {\<Go to ISI\>://WOS:001735510300001},
doi = {10.1021/acs.jctc.6c00002},
issn = {1549-9618},
journal = {Journal of Chemical Theory and Computation},
abstract = {The accurate simulation of dissipative quantum dynamics subject to a non-Markovian environment poses persistent numerical challenges, in particular, for structured environments, where sharp mode resonances induce long-time system bath correlations. We present a scalable distributed memory implementation of the mask-assisted coarse graining of influence coefficients (MACGIC)-quasi-adiabatic propagator path integral (-QUAPI) method that exploits the memory resources of multiple compute nodes and mitigates the memory bottleneck of the method via a new premerging algorithm and a hash-based look-up (hMACGIC-QUAPI) while preserving numerical accuracy. The source code of the hMACGIC-QUAPI implementation is available in a publicly accessible Git repository under GPL license. The developed distributed memory implementation spreads the paths over the computing nodes by means of the MPI protocol, and efficient high level path management is achieved via the hash map-based implementation with constant access time. The efficiency of the implementation is demonstrated in large-scale dissipative quantum dynamics simulations that account for the coupling to a structured non-Markovian environment containing a sharp resonance, a setup for which convergence properties are investigated in depth. Broad applicability and the nonperturbative nature of the simulation method is illustrated via the tuning of the mode resonance frequency of the structured environment with respect to the characteristic system frequency. The simulations reveal a splitting of resonances due to a strong system-environment interaction and the emergence of sidebands due to multiexcitations of the bosonic mode that are not accounted for in perturbative approaches. The simulations demonstrate the versatility of the new hMACGIC-QUAPI method in the presence of strong non-Markovian system bath correlations.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The accurate simulation of dissipative quantum dynamics subject to a non-Markovian environment poses persistent numerical challenges, in particular, for structured environments, where sharp mode resonances induce long-time system bath correlations. We present a scalable distributed memory implementation of the mask-assisted coarse graining of influence coefficients (MACGIC)-quasi-adiabatic propagator path integral (-QUAPI) method that exploits the memory resources of multiple compute nodes and mitigates the memory bottleneck of the method via a new premerging algorithm and a hash-based look-up (hMACGIC-QUAPI) while preserving numerical accuracy. The source code of the hMACGIC-QUAPI implementation is available in a publicly accessible Git repository under GPL license. The developed distributed memory implementation spreads the paths over the computing nodes by means of the MPI protocol, and efficient high level path management is achieved via the hash map-based implementation with constant access time. The efficiency of the implementation is demonstrated in large-scale dissipative quantum dynamics simulations that account for the coupling to a structured non-Markovian environment containing a sharp resonance, a setup for which convergence properties are investigated in depth. Broad applicability and the nonperturbative nature of the simulation method is illustrated via the tuning of the mode resonance frequency of the structured environment with respect to the characteristic system frequency. The simulations reveal a splitting of resonances due to a strong system-environment interaction and the emergence of sidebands due to multiexcitations of the bosonic mode that are not accounted for in perturbative approaches. The simulations demonstrate the versatility of the new hMACGIC-QUAPI method in the presence of strong non-Markovian system bath correlations.
2.
J Rojas, Z Wang, F Liu, J A Fereiro, D Chryssikos, T Dittrich, D Leister, D Cahen, M Tornow
Current Rectification Via Photosystem I Monolayers Induced by Their Orientation on Hydrophilic Self-Assembled Monolayers on Titanium Nitride Proceedings Article
In: 2024 IEEE 24th International Conference on Nanotechnology (NANO), pp. 266-271, 0000, ISBN: 1944-9380.
@inproceedings{nokey,
title = {Current Rectification Via Photosystem I Monolayers Induced by Their Orientation on Hydrophilic Self-Assembled Monolayers on Titanium Nitride},
author = {J Rojas and Z Wang and F Liu and J A Fereiro and D Chryssikos and T Dittrich and D Leister and D Cahen and M Tornow},
doi = {10.1109/NANO61778.2024.10628956},
isbn = {1944-9380},
booktitle = {2024 IEEE 24th International Conference on Nanotechnology (NANO)},
pages = {266-271},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
1.
X Zhu, P Rinke, D A Egger
Predicting temperature-dependent optoelectronic properties of semiconductor defects with equivariant neural networks Journal Article
In: npj Computational Materials, vol. 12, no. 1, pp. 176, 0000, ISSN: 2057-3960.
@article{nokey,
title = {Predicting temperature-dependent optoelectronic properties of semiconductor defects with equivariant neural networks},
author = {X Zhu and P Rinke and D A Egger},
url = {https://doi.org/10.1038/s41524-026-02111-z},
doi = {10.1038/s41524-026-02111-z},
issn = {2057-3960},
journal = {npj Computational Materials},
volume = {12},
number = {1},
pages = {176},
abstract = {The presence of defects strongly influences semiconductor behavior. However, predicting the electronic properties of defective materials at finite temperatures remains computationally expensive even with density functional theory due to the large number of atoms in the simulation cell and the multitude of thermally accessible configurations. Here, we present a neural network-based framework to investigate the electronic properties of defective semiconductors at finite temperatures efficiently. We develop an active learning approach that integrates two advanced equivariant graph neural networks: MACE for atomic energies and forces and DeepH-E3 for the electronic Hamiltonian. Focusing on representative point defects in GaAs, we demonstrate computational accuracy comparable to density functional theory at a fraction of the computational cost, predicting the temperature-dependent band gap of defective GaAs directly from larger scale molecular dynamics trajectories with an accuracy of few tens of meV. Our results highlight the potential of equivariant neural networks for accurate atomic-scale predictions in complex, dynamically evolving materials.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The presence of defects strongly influences semiconductor behavior. However, predicting the electronic properties of defective materials at finite temperatures remains computationally expensive even with density functional theory due to the large number of atoms in the simulation cell and the multitude of thermally accessible configurations. Here, we present a neural network-based framework to investigate the electronic properties of defective semiconductors at finite temperatures efficiently. We develop an active learning approach that integrates two advanced equivariant graph neural networks: MACE for atomic energies and forces and DeepH-E3 for the electronic Hamiltonian. Focusing on representative point defects in GaAs, we demonstrate computational accuracy comparable to density functional theory at a fraction of the computational cost, predicting the temperature-dependent band gap of defective GaAs directly from larger scale molecular dynamics trajectories with an accuracy of few tens of meV. Our results highlight the potential of equivariant neural networks for accurate atomic-scale predictions in complex, dynamically evolving materials.