Domain wall structures form spontaneously due to epitaxial misfit during thin film growth.Imaging the dynamics of domains and domain walls at ultrafast timescales can provide fundamental clues to features that impact ...Domain wall structures form spontaneously due to epitaxial misfit during thin film growth.Imaging the dynamics of domains and domain walls at ultrafast timescales can provide fundamental clues to features that impact electrical transport in electronic devices.Recently,deep learning based methods showed promising phase retrieval(PR)performance,allowing intensity-only measurements to be transformed into snapshot real space images.While the Fourier imaging model involves complex-valued quantities,most existing deep learning based methods solve the PR problem with real-valued based models,where the connection between amplitude and phase is ignored.To this end,we involve complex numbers operation in the neural network to preserve the amplitude and phase connection.Therefore,we employ the complex-valued neural network for solving the PR problem and evaluate it on Bragg coherent diffraction data streams collected from an epitaxial La_(2-x)Sr_(x)CuO_(4)(LSCO)thin film using an X-ray Free Electron Laser(XFEL).Our proposed complex-valued neural network based approach outperforms the traditional real-valued neural network methods in both supervised and unsupervised learning manner.Phase domains are also observed from the LSCO thin film at an ultrafast timescale using the complex-valued neural network.展开更多
The past decades have witnessed the development of new X-ray beam sources with brightness growing at a rate surpassing Moore’s law.Current and upcoming diffraction limited and fully coherent X-ray beam sources,includ...The past decades have witnessed the development of new X-ray beam sources with brightness growing at a rate surpassing Moore’s law.Current and upcoming diffraction limited and fully coherent X-ray beam sources,including multi-bend achromat based synchrotron sources and high repetition rate X-ray free electron lasers,puts increasingly stringent requirements on stability and accuracy of X-ray optics systems.Parasitic motion errors at sub-micro radian scale in beam transport and beam conditioning optics can lead to significant loss of coherence and brightness delivered from source to experiment.To address this challenge,we incorporated optical metrology based on interferometric length and angle sensing and real-time correction as part of the X-ray optics motion control system.A prototype X-ray optics system was constructed following the optical layout of a tunable X-ray cavity.On-line interferometric metrology enabled dynamical feedback to a motion control system to track and compensate for motion errors.The system achieved sub-microradian scale performance,as multiple optical elements are synchronously and continuously adjusted.This first proof of principle measurement demonstrated both the potential and necessity of incorporating optical metrology as part of the motion control architecture for large scale X-ray optical systems such as monochromators,delay lines,and in particular,X-ray cavity systems to enable the next generation cavity-based X-ray free electron lasers.展开更多
Unraveling the exact nature of nonequilibrium and correlated interactions is paramount for continued progress in many areas of condensed matter science. Such insight is a prerequisite to develop an engineered approach...Unraveling the exact nature of nonequilibrium and correlated interactions is paramount for continued progress in many areas of condensed matter science. Such insight is a prerequisite to develop an engineered approach for smart materials with targeted properties designed to address standing needs such as efficient light harvesting, energy storage, or information processing. For this goal, it is critical to unravel the dynamics of the energy conversion processes between carriers in the earliest time scales of the excitation dynamics. We discuss the implementation and benefits of attosecond soft x-ray core-level spectroscopy up to photon energies of 600 eV for measurements in solid-state systems. In particular, we examine how the pairing between coherent spectral coverage and temporal resolution provides a powerful new insight into the quantum dynamic interactions that determine the macroscopic electronic and optical response. We highlight the different building blocks of the methodology and point out the important aspects for its application from condensed matter studies to materials as thin as 25 nm. Furthermore, we discuss the technological developments in the field of tabletop attosecond soft x-ray sources with time-resolved measurements at the near and extended edge simultaneously and investigate the exciting prospective of extending such technique to the study of 2-dimensional materials.展开更多
基金supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,under Contract No.DE-SC0012704supported by EPSRC.Work at Argonne National Laboratory was supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,Materials Science and Engineering Division+2 种基金X.H.was supported by the Gordon and Betty Moore Foundation’s EPiQS Initiative through Grant No.GBMF9074S.D.M.and P.G.E.gratefully acknowledge support from the U.S.DOE Office of Science under grant no.DE-FG02-04ER46147from the US NSF through the University of Wisconsin Materials Research Science and Engineering Center(DMR-2309000 and DMR-1720415).
文摘Domain wall structures form spontaneously due to epitaxial misfit during thin film growth.Imaging the dynamics of domains and domain walls at ultrafast timescales can provide fundamental clues to features that impact electrical transport in electronic devices.Recently,deep learning based methods showed promising phase retrieval(PR)performance,allowing intensity-only measurements to be transformed into snapshot real space images.While the Fourier imaging model involves complex-valued quantities,most existing deep learning based methods solve the PR problem with real-valued based models,where the connection between amplitude and phase is ignored.To this end,we involve complex numbers operation in the neural network to preserve the amplitude and phase connection.Therefore,we employ the complex-valued neural network for solving the PR problem and evaluate it on Bragg coherent diffraction data streams collected from an epitaxial La_(2-x)Sr_(x)CuO_(4)(LSCO)thin film using an X-ray Free Electron Laser(XFEL).Our proposed complex-valued neural network based approach outperforms the traditional real-valued neural network methods in both supervised and unsupervised learning manner.Phase domains are also observed from the LSCO thin film at an ultrafast timescale using the complex-valued neural network.
基金support from the Laboratory Directed Research and Development program at the SLAC National Accelerator Laboratorythe National Science Foundation under Grant No.NSF-2011786Use of the Linac Coherent Light Source(LCLS),SLAC National Accelerator Laboratory,is supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences under Contract No.DE-AC02-76SF00515.
文摘The past decades have witnessed the development of new X-ray beam sources with brightness growing at a rate surpassing Moore’s law.Current and upcoming diffraction limited and fully coherent X-ray beam sources,including multi-bend achromat based synchrotron sources and high repetition rate X-ray free electron lasers,puts increasingly stringent requirements on stability and accuracy of X-ray optics systems.Parasitic motion errors at sub-micro radian scale in beam transport and beam conditioning optics can lead to significant loss of coherence and brightness delivered from source to experiment.To address this challenge,we incorporated optical metrology based on interferometric length and angle sensing and real-time correction as part of the X-ray optics motion control system.A prototype X-ray optics system was constructed following the optical layout of a tunable X-ray cavity.On-line interferometric metrology enabled dynamical feedback to a motion control system to track and compensate for motion errors.The system achieved sub-microradian scale performance,as multiple optical elements are synchronously and continuously adjusted.This first proof of principle measurement demonstrated both the potential and necessity of incorporating optical metrology as part of the motion control architecture for large scale X-ray optical systems such as monochromators,delay lines,and in particular,X-ray cavity systems to enable the next generation cavity-based X-ray free electron lasers.
基金J.B.acknowledges financial support from the European Research Council for ERC Advanced Grant"TRANSFORMER"(788218)ERC Proof of Concept Grant"miniX"(840010),FET-OPEN"PETACom"(829153),FET-OPEN"OPTOlogic"(899794)+5 种基金FET-OPEN"Twisted Nano(101046424),Laserlab-Europe(871124),Marie Sktodowska-Curie ITN"smart-X"(860553)MINECO for Plan Nacional PID2020-112664 GB-I00AGAUR for 2017 SGR 1639,MINECO for"Severo Ochoa"(CEX2019-000910-S)Fundacio Cellex Barcelona,the CERCA Programme/Generalitat de Catalunyathe Alexander von Humboldt Foundation for the Friedrich Wilhelm Bessel Prize.S.S.acknowledges Marie Sktodowska-Curie grant agreement no.713729(COFUND)M.R.and A.M.S.acknowledge Marie Sktodowska-Curie Grant agreement no.754510(PROBIST)。
文摘Unraveling the exact nature of nonequilibrium and correlated interactions is paramount for continued progress in many areas of condensed matter science. Such insight is a prerequisite to develop an engineered approach for smart materials with targeted properties designed to address standing needs such as efficient light harvesting, energy storage, or information processing. For this goal, it is critical to unravel the dynamics of the energy conversion processes between carriers in the earliest time scales of the excitation dynamics. We discuss the implementation and benefits of attosecond soft x-ray core-level spectroscopy up to photon energies of 600 eV for measurements in solid-state systems. In particular, we examine how the pairing between coherent spectral coverage and temporal resolution provides a powerful new insight into the quantum dynamic interactions that determine the macroscopic electronic and optical response. We highlight the different building blocks of the methodology and point out the important aspects for its application from condensed matter studies to materials as thin as 25 nm. Furthermore, we discuss the technological developments in the field of tabletop attosecond soft x-ray sources with time-resolved measurements at the near and extended edge simultaneously and investigate the exciting prospective of extending such technique to the study of 2-dimensional materials.
