Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Canadian Journal of Physics

Article

M. Grigorescu

Published Dec 1, 1998• 0 citations
Publisher

Abstract

The quantum dynamics of a Xe atom placed on the STM surfaceis studied considering two important types of nonstationary externalforces. These are the driving forces appearing during the application of avoltage pulse, and the fluctuating forces determined by the coupling to anOhmic environment. The localization probability on the tipduring voltage pulses of 20 and 7 ns with symmetric triangular andtrapezoidal shapes is calculated neglecting the environmental interactions.The results indicate that the atom dynamics in this case is reversible, andafter the pulse the transfer probability is small.The effects of the fluctuating forces produced by the coupling to thesurrounding electrons and surface phonons are studied in a static potential.It is shown that the thermal fluctuations at the environmental temperaturecan lead to irreversible atom tunneling through the potential barrier,described by an exponential decay law.PACS Nos.: 61.16.Di, 73.40.Gk, 05.40.+j

DOI
10.1139/p98-066

Related papers

Heating-assisted atom transfer inthe scanning tunneling microscope

M. Grigorescu

The effects of a voltage pulse on the localization probability for a Xe atom prepared in a pure state localized on the STM surface at 0 temperature is investigated by numerically integrating the time-dependent Schroedinger equation. In these calculations the environmental interactions are neglected, and voltage pulses of 20 and 7 ns with symmetric triangular and trapezoidal shapes are considered. The atom dynamics at an environmental temperature of 4 K is studied in the frame of a stochastic, non-linear Liouville equation for the density operator. It is shown that the irreversible transfer from surface to tip may be explained by thermal decoherence rather than by the driving force acting during the application of the voltage pulse.

arXiv:physics/9709030•Canadian Journal of Physics•Jan 1, 1998•2 citations

Atom oscillations in the scanning tunneling microscope

M. Grigorescu, P. Budau, N. Cârjan

The atom tunneling across the potential barrier separating the surface and the tip of the scanning tunneling microscope is investigated by semiclassical methods, and by integrating numerically the time-dependent Schr\"odinger equation. It is shown that the barrier crossing is explained by the resonance phenomenon of quantum coherence oscillations, rather than by exponential decay. The occurrence of these resonances at the variation of the bias voltage is studied for the first two isomeric states of a Xe atom in a surface-tip potential of double-well shape. The resonant bias voltages for these two states practically coincide, and at the first common resonance the effect of the environmental temperature is discussed. The results provide a useful frame for understanding the mechanism of atom transfer in scanning tunneling microscopy.

Physical review. B, Condensed matter•Mar 15, 1997•8 citations

Atom transfer in the STM double-well potential during a voltage pulse

P. Budau, M. Grigorescu

The dynamics of atom transfer in the scanning tunneling microscope double-well potential is investigated using the time-dependent Schr\"odinger equation. The transfer is induced by variable electric fields applied between the surface and the tip. The effects related to the crossing of a resonant bias voltage, when atomic quantum-coherence oscillations between the potential wells may appear, are discussed.

Physical review. B, Condensed matter•Mar 15, 1998•10 citations

Quantum atom switch: Tunneling of Xe atoms

Juan José Sáenz, N. Garcı́a

Recently Eigler, Lutz, and Rudge [Nature 352, 600 (1991)] have reported a bistable switch that derives its function from the motion of a single Xe atom. It has been shown that this atom can be transferred, in a reversible way, from a scanning-tunneling-microscope tip to a sample by means of a voltage pulse. In this paper we show that the atom transfer process can be understood in terms of a single-atom-tunneling process, while a mechanism similar to the heating-assisted electromigration cannot account for the experimental observations. We find that there is a nonzero probability of atom transfer even at zero applied voltage, i.e., the transfer rate cannot follow a power-law dependence with the applied pulse at small voltages. We present a tunneling model, based on the charge transfer from the metal to the 6s resonance of the Xe atoms, which is consistent with the available experimental data.

Physical review. B, Condensed matter•Mar 15, 1993•25 citations

The Quantum Mechanical Tunneling under the Influence of Environment: Using the Method of Density Matrix

Hiroshi Kawamoto

The purpose of this paper is to study an effect of an environment on a quantum tunneling. Here, the system we consider is of a symmetric two-level type with “bare” tunneling frequency Δω0, and the correlation time of actions due to the environment, τc, is assumed to be much shorter than Δω0-1. In the investigations, the method of density matrix is used, and a coupling between the system and the environment is included up to lowest nontrivial order. After calculations, we reach the following conclusions: First, the possibility of the quantum tunneling is, in a high temperature range βℏΔω0 ≪1, washed out by the thermal actions from the environment. In the inverse case βℏΔω0 ≪1, where the quantum fluctuation of the environment plays a dominant role, the possibility of the quantum tunneling remains. Secondaly, in the case βℏΔω0 ≪1, the dissipation effect depresses the tunneling probability, while the potential barrier is effectively lowered by the actions due to the environment.

Progress of Theoretical Physics•Jun 1, 1984•2 citations

Quantum Tunneling

Frank S. Levin

Abstract Quantum tunneling, wherein a quanject has a non-zero probability of tunneling into and then exiting a barrier of finite width and height, is the subject of Chapter 13. The description for the one-dimensional case is extended to the barrier being inverted, which forms an attractive potential well. The first application of this analysis is to the emission of alpha particles from the decay of radioactive nuclei, where the alpha-nucleus attraction is modeled by a potential well and the barrier is the repulsive Coulomb potential. Excellent results are obtained. Ditto for the similar analysis of proton burning in stars and yet a different analysis that explains tunneling through a Josephson junction, the connector between two superconductors. The final application is to the scanning tunneling microscope, a device that allows the microscopic surfaces of solids to be mapped via electrons from the surface molecules tunneling into the tip of the STM probe.

•Sep 21, 2017•0 citations
The quantum dynamics of a Xe atom placed on the STM surfaceis studied considering two important types of nonstationary externalforces. These are the driving forces appearing during the application of avoltage pulse, and the fluctuating forces determined by the coupling to anOhmic environment. The localization probability on the tipduring voltage pulses of 20 and 7 ns with symmetric triangular andtrapezoidal shapes is calculated neglecting the environmental interactions.The results indicate that the atom dynamics in this case is reversible, andafter the pulse the transfer probability is small.The effects of the fluctuating forces produced by the coupling to thesurrounding electrons and surface phonons are studied in a static potential.It is shown that the thermal fluctuations at the environmental temperaturecan lead to irreversible atom tunneling through the potential barrier,described by an exponential decay law.PACS Nos.: 61.16.Di, 73.40.Gk, 05.40.+j
The effects of a voltage pulse on the localization probability for a Xe atom prepared in a pure state localized on the STM surface at 0 temperature is investigated by numerically integrating the time-dependent Schroedinger equation. In these calculations the environmental interactions are neglected, and voltage pulses of 20 and 7 ns with symmetric triangular and trapezoidal shapes are considered. The atom dynamics at an environmental temperature of 4 K is studied in the frame of a stochastic, non-linear Liouville equation for the density operator. It is shown that the irreversible transfer from surface to tip may be explained by thermal decoherence rather than by the driving force acting during the application of the voltage pulse.
The atom tunneling across the potential barrier separating the surface and the tip of the scanning tunneling microscope is investigated by semiclassical methods, and by integrating numerically the time-dependent Schr\"odinger equation. It is shown that the barrier crossing is explained by the resonance phenomenon of quantum coherence oscillations, rather than by exponential decay. The occurrence of these resonances at the variation of the bias voltage is studied for the first two isomeric states of a Xe atom in a surface-tip potential of double-well shape. The resonant bias voltages for these two states practically coincide, and at the first common resonance the effect of the environmental temperature is discussed. The results provide a useful frame for understanding the mechanism of atom transfer in scanning tunneling microscopy.
Recently Eigler, Lutz, and Rudge [Nature 352, 600 (1991)] have reported a bistable switch that derives its function from the motion of a single Xe atom. It has been shown that this atom can be transferred, in a reversible way, from a scanning-tunneling-microscope tip to a sample by means of a voltage pulse. In this paper we show that the atom transfer process can be understood in terms of a single-atom-tunneling process, while a mechanism similar to the heating-assisted electromigration cannot account for the experimental observations. We find that there is a nonzero probability of atom transfer even at zero applied voltage, i.e., the transfer rate cannot follow a power-law dependence with the applied pulse at small voltages. We present a tunneling model, based on the charge transfer from the metal to the 6s resonance of the Xe atoms, which is consistent with the available experimental data.
The purpose of this paper is to study an effect of an environment on a quantum tunneling. Here, the system we consider is of a symmetric two-level type with “bare” tunneling frequency Δω0, and the correlation time of actions due to the environment, τc, is assumed to be much shorter than Δω0-1. In the investigations, the method of density matrix is used, and a coupling between the system and the environment is included up to lowest nontrivial order. After calculations, we reach the following conclusions: First, the possibility of the quantum tunneling is, in a high temperature range βℏΔω0 ≪1, washed out by the thermal actions from the environment. In the inverse case βℏΔω0 ≪1, where the quantum fluctuation of the environment plays a dominant role, the possibility of the quantum tunneling remains. Secondaly, in the case βℏΔω0 ≪1, the dissipation effect depresses the tunneling probability, while the potential barrier is effectively lowered by the actions due to the environment.
Abstract Quantum tunneling, wherein a quanject has a non-zero probability of tunneling into and then exiting a barrier of finite width and height, is the subject of Chapter 13. The description for the one-dimensional case is extended to the barrier being inverted, which forms an attractive potential well. The first application of this analysis is to the emission of alpha particles from the decay of radioactive nuclei, where the alpha-nucleus attraction is modeled by a potential well and the barrier is the repulsive Coulomb potential. Excellent results are obtained. Ditto for the similar analysis of proton burning in stars and yet a different analysis that explains tunneling through a Josephson junction, the connector between two superconductors. The final application is to the scanning tunneling microscope, a device that allows the microscopic surfaces of solids to be mapped via electrons from the surface molecules tunneling into the tip of the STM probe.