The chaotic ratchet effect for Bos-Einstein condensed atoms in an optical lattice is investigated. By using the direct perturbation method we obtain the chaotic solution of the condensed system. Theoretical analysis r...The chaotic ratchet effect for Bos-Einstein condensed atoms in an optical lattice is investigated. By using the direct perturbation method we obtain the chaotic solution of the condensed system. Theoretical analysis reveals that the transport of the condensed atoms in the ratchet potential is a chaotic one, and corresponding numerical results agree well with the theoretical results.展开更多
Using time-dependent Ginzburg-Landau formalism,we investigate the multiple reversals of ratchet effects in an unpatterned superconducting strip by the tilted dynamic pinning potential.In the case of collinear sliding ...Using time-dependent Ginzburg-Landau formalism,we investigate the multiple reversals of ratchet effects in an unpatterned superconducting strip by the tilted dynamic pinning potential.In the case of collinear sliding potential and Lorentz force,vortices are always confined in the channels induced by sliding potential.However,due to the inclination angle of sliding pinning potential with respect to the Lorentz force,vortices could be driven out of the channels,and unexpected results with multiple reversals of vortex rectifications are observed.The mechanism of multiple reversals of vortex rectifications is explored by analyzing different vortex motion scenarios with increasing ac current amplitudes.The multiple reversals of transverse and longitudinal ratchet effects can be highly controlled by ac amplitude and dynamic pinning velocity.What's more,at certain large current the ratchet effect reaches strongest within a wide range of pinning sliding velocity.展开更多
Using a two-dimensional ensemble Monte Carlo (EMC) method, electronic nanometer devices with different parameters are studied in detail. Calculation results show that at nanoscale the electric properties of interface ...Using a two-dimensional ensemble Monte Carlo (EMC) method, electronic nanometer devices with different parameters are studied in detail. Calculation results show that at nanoscale the electric properties of interface inside the devices play an important role in determining the working properties of the devices. By properly arranging device structures, surface charges originated from device fabrication can be exploited to produce a predetermined electric potential in the devices. Based on this fact, two structures that can lead to an asymmetric potential along their nanochannel are proposed for designing strong nonlinear devices. Further studies indicate that Ratchet effect brought by the asymmetric potential results in diode-like current-voltage characteristics of the devices. Through optimizing device parameters, zero threshold voltage can be achieved, which is desired for detecting applications. Moreover, since the devices are at nanoscale, simulation results reveal that used as rectifiers the working frequencies can be up to a few THz.展开更多
We employed molecular dynamics simulations to investigate the directed transport of a double-stranded oligonucleotide(ds DNA)through a single-walled carbon nanotube(SWNT)powered by external mechanical vibrations.It is...We employed molecular dynamics simulations to investigate the directed transport of a double-stranded oligonucleotide(ds DNA)through a single-walled carbon nanotube(SWNT)powered by external mechanical vibrations.It is thermodynamically favorable for ds DNA to adsorb inside the SWNT,and its transport through the nanotube is challenging due to the high energy barrier.However,we demonstrate that mechanical vibrations at specific frequencies can effectively drive the ds DNA through the nanotube based on a ratchet effect.The system is driven away from thermal equilibrium,and the spatial inversion symmetry is broken by mechanical vibrations.This study provides valuable insights into the mechanisms of mechanically activated DNA transport and highlights the potential of using SWNTs as nanoscale conduits for ds DNA delivery in nanobiotechnology and biomedicine.展开更多
基金the Key Research Foundation of the Education Bureau of Hunan Province of China under Grant No.08A015the Natural Science Foundation of Hunan Province of China under Grant No.06JJ2014 and 04JJ40006the National Natural Science Foundation of China under Grant No.10575034
文摘The chaotic ratchet effect for Bos-Einstein condensed atoms in an optical lattice is investigated. By using the direct perturbation method we obtain the chaotic solution of the condensed system. Theoretical analysis reveals that the transport of the condensed atoms in the ratchet potential is a chaotic one, and corresponding numerical results agree well with the theoretical results.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11702034,11972298,and 11702218)the China Postdoctoral Science Foundation(Grant No.2019M663812)+1 种基金the Fundamental Research Funds for the Central Universities,China(Grant Nos.300102129104,3102018zy013,and 3102017jc01003)the Young Talent Fund of University Association for Science and Technology in Shaanxi,China(Grant Nos.20180503 and 20180501).
文摘Using time-dependent Ginzburg-Landau formalism,we investigate the multiple reversals of ratchet effects in an unpatterned superconducting strip by the tilted dynamic pinning potential.In the case of collinear sliding potential and Lorentz force,vortices are always confined in the channels induced by sliding potential.However,due to the inclination angle of sliding pinning potential with respect to the Lorentz force,vortices could be driven out of the channels,and unexpected results with multiple reversals of vortex rectifications are observed.The mechanism of multiple reversals of vortex rectifications is explored by analyzing different vortex motion scenarios with increasing ac current amplitudes.The multiple reversals of transverse and longitudinal ratchet effects can be highly controlled by ac amplitude and dynamic pinning velocity.What's more,at certain large current the ratchet effect reaches strongest within a wide range of pinning sliding velocity.
文摘Using a two-dimensional ensemble Monte Carlo (EMC) method, electronic nanometer devices with different parameters are studied in detail. Calculation results show that at nanoscale the electric properties of interface inside the devices play an important role in determining the working properties of the devices. By properly arranging device structures, surface charges originated from device fabrication can be exploited to produce a predetermined electric potential in the devices. Based on this fact, two structures that can lead to an asymmetric potential along their nanochannel are proposed for designing strong nonlinear devices. Further studies indicate that Ratchet effect brought by the asymmetric potential results in diode-like current-voltage characteristics of the devices. Through optimizing device parameters, zero threshold voltage can be achieved, which is desired for detecting applications. Moreover, since the devices are at nanoscale, simulation results reveal that used as rectifiers the working frequencies can be up to a few THz.
基金supported by the National Natural Science Foundation of China(Grant No.11875237)。
文摘We employed molecular dynamics simulations to investigate the directed transport of a double-stranded oligonucleotide(ds DNA)through a single-walled carbon nanotube(SWNT)powered by external mechanical vibrations.It is thermodynamically favorable for ds DNA to adsorb inside the SWNT,and its transport through the nanotube is challenging due to the high energy barrier.However,we demonstrate that mechanical vibrations at specific frequencies can effectively drive the ds DNA through the nanotube based on a ratchet effect.The system is driven away from thermal equilibrium,and the spatial inversion symmetry is broken by mechanical vibrations.This study provides valuable insights into the mechanisms of mechanically activated DNA transport and highlights the potential of using SWNTs as nanoscale conduits for ds DNA delivery in nanobiotechnology and biomedicine.
