As key components of artificial afferent nervous systems,synaptic devices can mimic the physiological synaptic behaviors,which have attracted extensive attentions.Here,a flexible tribotronic artificial synapse(TAS)wit...As key components of artificial afferent nervous systems,synaptic devices can mimic the physiological synaptic behaviors,which have attracted extensive attentions.Here,a flexible tribotronic artificial synapse(TAS)with bioinspired neurosensory behavior is developed.The triboelectric potential generated by the external contact electrification is used as the ion-gel-gate voltage of the organic thin film transistor,which can tune the carriers transport through the migration/accumulation of ions.The TAS successfully demonstrates a series of synaptic behaviors by external stimuli,such as excitatory postsynaptic current,paired-pulse facilitation,and the hierarchical memory process from sensory memory to short-term memory and long-term memory.Moreover,the synaptic behaviors remained stable under the strain condition with a bending radius of 20 mm,and the TAS still exhibits excellent durability after 1000 bending cycles.Finally,Pavlovian conditioning has been successfully mimicked by applying force and vibration as food and bell,respectively.This work demonstrates a bioinspired flexible artificial synapse that will help to facilitate the development of artificial afferent nervous systems,which is great significance to the practical application of artificial limbs,robotics,and bionics in future.展开更多
Periodic structures structured as photonic crystals and optical lattices are fascinating for nonlinear waves engineering in the optics and ultracold atoms communities.Moiréphotonic and optical lattices—two-dimen...Periodic structures structured as photonic crystals and optical lattices are fascinating for nonlinear waves engineering in the optics and ultracold atoms communities.Moiréphotonic and optical lattices—two-dimensional twisted patterns lie somewhere in between perfect periodic structures and aperiodic ones—are a new emerging investigative tool for studying nonlinear localized waves of diverse types.Herein,a theory of two-dimensional spatial localization in nonlinear periodic systems with fractional-order diffraction(linear nonlocality)and moiréoptical lattices is investigated.Specifically,the flat-band feature is well preserved in shallow moiréoptical lattices which,interact with the defocusing nonlinearity of the media,can support fundamental gap solitons,bound states composed of several fundamental solitons,and topological states(gap vortices)with vortex charge s=1 and 2,all populated inside the finite gaps of the linear Bloch-wave spectrum.Employing the linear-stability analysis and direct perturbed simulations,the stability and instability properties of all the localized gap modes are surveyed,highlighting a wide stability region within the first gap and a limited one(to the central part)for the third gap.The findings enable insightful studies of highly localized gap modes in linear nonlocality(fractional)physical systems with shallow moirépatterns that exhibit extremely flat bands.展开更多
Considerable attention has been recently paid to elucidation the linear,nonlinear and quantum physics of moire patterns because of the innate extraordinary physical properties and potential applications.Particularly,m...Considerable attention has been recently paid to elucidation the linear,nonlinear and quantum physics of moire patterns because of the innate extraordinary physical properties and potential applications.Particularly,moire superlattices consisted of two periodic structures with a twist angle offer a new platform for studying soliton theory and its practical applications in various physical systems including optics,while such studies were so far limited to reversible or conservative nonlinear systems.Herein,we provide insight into soliton physics in dissipative physical settings with moire optical lattices,using numerical simulations and theoretical analysis.We reveal linear localization-delocalization transitions,and find that such nonlinear settings support plentiful localized gap modes representing as dissipative gap solitons and vortices in periodic and aperiodic moire optical lattices,and identify numerically the stable regions of these localized modes.Our predicted dissipative localized modes provide insightful understanding of soliton physics in dissipative nonlinear systems since dissipation is everywhere.展开更多
Parity–time(PT) symmetric lattices have been widely studied in controlling the flow of waves, and recently,moiré superlattices, connecting the periodic and non-periodic potentials, have been introduced for explo...Parity–time(PT) symmetric lattices have been widely studied in controlling the flow of waves, and recently,moiré superlattices, connecting the periodic and non-periodic potentials, have been introduced for exploring unconventional physical properties in physics, while the combination of both and nonlinear waves therein remains unclear. Here, we report a theoretical survey of nonlinear wave localizations in PT symmetric moiré optical lattices, with the aim of revealing localized gap modes of different types and their stabilization mechanism.We uncover the formation, properties, and dynamics of fundamental and higher-order gap solitons as well as vortical ones with topological charge, all residing in the finite bandgaps of the underlying linear-Bloch wave spectrum. The stability regions of localized gap modes are inspected in two numerical ways: linear-stability analysis and direct perturbance simulations. Our results provide an insightful understanding of soliton physics in combined versatile platforms of PT symmetric systems and moiré patterns.展开更多
The nonlinear lattice - a new and nonlinear class of periodic potentials - was recently introduced to generate various nonlinear localized modes. Several attempts failed to stabilize two-dimensional （2D） solitons ag...The nonlinear lattice - a new and nonlinear class of periodic potentials - was recently introduced to generate various nonlinear localized modes. Several attempts failed to stabilize two-dimensional （2D） solitons against their intrinsic critical collapse in Kerr media. Here, we provide a possibility for supporting 2D matter-wave solitons and vortices in an extended setting - the cubic and quintic model - by introducing another nonlinear lattice whose period is controllable and can be different from its cubic counterpart, to its quintic nonlinearity, therefore making a fully ＂nonlinear quasi-crystal＂. A variational approximation based on Gaussian ansatz is developed for the fundamental solitons and in particular, their stability exactly follows the inverted Vakhitov-Kolokolov stability criterion, whereas the vortex solitons are only studied by means of numerical methods. Stability regions for two types of localized mode -- the fundamental and vortex solitons -- are provided. A noteworthy feature of the localized solutions is that the vortex solitons are stable only when the period of the quintic nonlinear lattice is the same as the cubic one or when the quintic nonlinearity is constant, while the stable fundamental solitons can be created under looser conditions. Our physical setting （cubic-quintic model） is in the framework of the Gross-Pitaevskii equation or nonlinear Schr6dinger equation, the predicted localized modes thus may be implemented in Bose-Einstein condensates and nonlinear optical media with tunable cubic and quintic nonlinearities.展开更多
Electromagnetically induced optical(or photonic)lattices via atomic coherence in atomic ensembles have recently received great theoretical and experimental interest.We here conceive a way to generate electromagnetical...Electromagnetically induced optical(or photonic)lattices via atomic coherence in atomic ensembles have recently received great theoretical and experimental interest.We here conceive a way to generate electromagnetically induced moiréoptical lattices—a twisted periodic pattern when two identical periodic patterns(lattices)are overlapped in a twisted angle(θ)—in a three-level coherent atomic gas working under electromagnetically induced transparency.We show that,changing the twisted angle and relative strength between the two constitutive sublattices,the moiréBloch bands that are extremely flattened can always appear,resembling the typical flat-band and moiréphysics found in other contexts.Dynamics of light propagation in the induced periodic structures demonstrating the unique linear localization and delocalization properties are also revealed.Our scheme can be implemented in a Rubidium atomic medium,where the predicted moiréoptical lattices and flattened bands are naturally observable.展开更多
Bose-Einstein condensate(BEC)exhibits a variety of fascinating and unexpected macroscopic phenomena,and has attracted sustained attention in recent years-particularly in the field of solitons and associated nonlinear ...Bose-Einstein condensate(BEC)exhibits a variety of fascinating and unexpected macroscopic phenomena,and has attracted sustained attention in recent years-particularly in the field of solitons and associated nonlinear phenomena.Meanwhile,optical lattices have emerged as a versatile toolbox for understanding the properties and controlling the dynamics of BEC,among which the realization of bright gap solitons is an iconic result.However,the dark gap solitons are still experimentally unproven,and their properties in more than one dimension remain unknown.In light of this,we describe,numerically and theoretically,the formation and stability properties of gap-type dark localized modes in the context of ultracold atoms trapped in optical lattices.Two kinds of stable dark localized modes-gap solitons and soliton clusters-are predicted in both the one-and two-dimensional geometries.The vortical counterparts of both modes are also constructed in two dimensions.A unique feature is the existence of a nonlinear Bloch-wave background on which all above gap modes are situated.By employing linear-stability analysis and direct simulations,stability regions of the predicted modes are obtained.Our results offer the possibility of observing dark gap localized structures with cutting-edge techniques in ultracold atoms experiments and beyond,including in optics with photonic crystals and lattices.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.51922023,61874011)the China Postdoctoral Science Foundation(Grant No.2021M703159)Fundamental Research Funds for the Central Universities(Grant No.E1EG6804).
文摘As key components of artificial afferent nervous systems,synaptic devices can mimic the physiological synaptic behaviors,which have attracted extensive attentions.Here,a flexible tribotronic artificial synapse(TAS)with bioinspired neurosensory behavior is developed.The triboelectric potential generated by the external contact electrification is used as the ion-gel-gate voltage of the organic thin film transistor,which can tune the carriers transport through the migration/accumulation of ions.The TAS successfully demonstrates a series of synaptic behaviors by external stimuli,such as excitatory postsynaptic current,paired-pulse facilitation,and the hierarchical memory process from sensory memory to short-term memory and long-term memory.Moreover,the synaptic behaviors remained stable under the strain condition with a bending radius of 20 mm,and the TAS still exhibits excellent durability after 1000 bending cycles.Finally,Pavlovian conditioning has been successfully mimicked by applying force and vibration as food and bell,respectively.This work demonstrates a bioinspired flexible artificial synapse that will help to facilitate the development of artificial afferent nervous systems,which is great significance to the practical application of artificial limbs,robotics,and bionics in future.
基金This work was supported by the National Natural Science Foundation of China(NSFC)(No.12074423)Young Scholar of Chinese Academy of Sciences in Western China(No.XAB2021YN18)China Postdoctoral Science Foundation(No.2023M733722).
文摘Periodic structures structured as photonic crystals and optical lattices are fascinating for nonlinear waves engineering in the optics and ultracold atoms communities.Moiréphotonic and optical lattices—two-dimensional twisted patterns lie somewhere in between perfect periodic structures and aperiodic ones—are a new emerging investigative tool for studying nonlinear localized waves of diverse types.Herein,a theory of two-dimensional spatial localization in nonlinear periodic systems with fractional-order diffraction(linear nonlocality)and moiréoptical lattices is investigated.Specifically,the flat-band feature is well preserved in shallow moiréoptical lattices which,interact with the defocusing nonlinearity of the media,can support fundamental gap solitons,bound states composed of several fundamental solitons,and topological states(gap vortices)with vortex charge s=1 and 2,all populated inside the finite gaps of the linear Bloch-wave spectrum.Employing the linear-stability analysis and direct perturbed simulations,the stability and instability properties of all the localized gap modes are surveyed,highlighting a wide stability region within the first gap and a limited one(to the central part)for the third gap.The findings enable insightful studies of highly localized gap modes in linear nonlocality(fractional)physical systems with shallow moirépatterns that exhibit extremely flat bands.
基金supported by the National Natural Science Foundation of China(NSFC)(12074423,11925108,12301306)the Young Scholar of Chinese Academy of Sciences in western China(XAB2021YN18)+1 种基金the Provisional Science Fund for Distinguished Young Scholars of Shaanxi(2024JC-JCQN-11)the Beijing Natural Science Foundation(1234039).
文摘Considerable attention has been recently paid to elucidation the linear,nonlinear and quantum physics of moire patterns because of the innate extraordinary physical properties and potential applications.Particularly,moire superlattices consisted of two periodic structures with a twist angle offer a new platform for studying soliton theory and its practical applications in various physical systems including optics,while such studies were so far limited to reversible or conservative nonlinear systems.Herein,we provide insight into soliton physics in dissipative physical settings with moire optical lattices,using numerical simulations and theoretical analysis.We reveal linear localization-delocalization transitions,and find that such nonlinear settings support plentiful localized gap modes representing as dissipative gap solitons and vortices in periodic and aperiodic moire optical lattices,and identify numerically the stable regions of these localized modes.Our predicted dissipative localized modes provide insightful understanding of soliton physics in dissipative nonlinear systems since dissipation is everywhere.
基金National Natural Science Foundation of China(12074423,61690222,61690224)Young Scholars of Chinese Academy of Sciences in Western China Program(XAB2021YN18)
文摘Parity–time(PT) symmetric lattices have been widely studied in controlling the flow of waves, and recently,moiré superlattices, connecting the periodic and non-periodic potentials, have been introduced for exploring unconventional physical properties in physics, while the combination of both and nonlinear waves therein remains unclear. Here, we report a theoretical survey of nonlinear wave localizations in PT symmetric moiré optical lattices, with the aim of revealing localized gap modes of different types and their stabilization mechanism.We uncover the formation, properties, and dynamics of fundamental and higher-order gap solitons as well as vortical ones with topological charge, all residing in the finite bandgaps of the underlying linear-Bloch wave spectrum. The stability regions of localized gap modes are inspected in two numerical ways: linear-stability analysis and direct perturbance simulations. Our results provide an insightful understanding of soliton physics in combined versatile platforms of PT symmetric systems and moiré patterns.
文摘The nonlinear lattice - a new and nonlinear class of periodic potentials - was recently introduced to generate various nonlinear localized modes. Several attempts failed to stabilize two-dimensional （2D） solitons against their intrinsic critical collapse in Kerr media. Here, we provide a possibility for supporting 2D matter-wave solitons and vortices in an extended setting - the cubic and quintic model - by introducing another nonlinear lattice whose period is controllable and can be different from its cubic counterpart, to its quintic nonlinearity, therefore making a fully ＂nonlinear quasi-crystal＂. A variational approximation based on Gaussian ansatz is developed for the fundamental solitons and in particular, their stability exactly follows the inverted Vakhitov-Kolokolov stability criterion, whereas the vortex solitons are only studied by means of numerical methods. Stability regions for two types of localized mode -- the fundamental and vortex solitons -- are provided. A noteworthy feature of the localized solutions is that the vortex solitons are stable only when the period of the quintic nonlinear lattice is the same as the cubic one or when the quintic nonlinearity is constant, while the stable fundamental solitons can be created under looser conditions. Our physical setting （cubic-quintic model） is in the framework of the Gross-Pitaevskii equation or nonlinear Schr6dinger equation, the predicted localized modes thus may be implemented in Bose-Einstein condensates and nonlinear optical media with tunable cubic and quintic nonlinearities.
基金supported by the National Natural Science Foundation of China(Grant Nos.11704066,12074423,12074063),and Jiangxi Provincial Natural Science Foundation(Grant No.20202BABL211013).
文摘Electromagnetically induced optical(or photonic)lattices via atomic coherence in atomic ensembles have recently received great theoretical and experimental interest.We here conceive a way to generate electromagnetically induced moiréoptical lattices—a twisted periodic pattern when two identical periodic patterns(lattices)are overlapped in a twisted angle(θ)—in a three-level coherent atomic gas working under electromagnetically induced transparency.We show that,changing the twisted angle and relative strength between the two constitutive sublattices,the moiréBloch bands that are extremely flattened can always appear,resembling the typical flat-band and moiréphysics found in other contexts.Dynamics of light propagation in the induced periodic structures demonstrating the unique linear localization and delocalization properties are also revealed.Our scheme can be implemented in a Rubidium atomic medium,where the predicted moiréoptical lattices and flattened bands are naturally observable.
基金This work was supported,in part,by the National Natural Science Foundation of China(Project Nos.61690224 and 61690222)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Project No.2016357).
文摘Bose-Einstein condensate(BEC)exhibits a variety of fascinating and unexpected macroscopic phenomena,and has attracted sustained attention in recent years-particularly in the field of solitons and associated nonlinear phenomena.Meanwhile,optical lattices have emerged as a versatile toolbox for understanding the properties and controlling the dynamics of BEC,among which the realization of bright gap solitons is an iconic result.However,the dark gap solitons are still experimentally unproven,and their properties in more than one dimension remain unknown.In light of this,we describe,numerically and theoretically,the formation and stability properties of gap-type dark localized modes in the context of ultracold atoms trapped in optical lattices.Two kinds of stable dark localized modes-gap solitons and soliton clusters-are predicted in both the one-and two-dimensional geometries.The vortical counterparts of both modes are also constructed in two dimensions.A unique feature is the existence of a nonlinear Bloch-wave background on which all above gap modes are situated.By employing linear-stability analysis and direct simulations,stability regions of the predicted modes are obtained.Our results offer the possibility of observing dark gap localized structures with cutting-edge techniques in ultracold atoms experiments and beyond,including in optics with photonic crystals and lattices.
