Papers by Christian Joachim
arXiv (Cornell University), Mar 10, 2016
The spectrum of 1-state and 2-states per line quantum buses is used to determine the effective V ... more The spectrum of 1-state and 2-states per line quantum buses is used to determine the effective V ab (N) electronic coupling between emitter and receiver states through the bus as a function of the number N of parallel lines in the bus. When the calculation of V ab (N) is spectrally difficult, an Heisenberg-Rabi time dependent quantum exchange process can be triggered through the bus by preparing a specific initial non-stationary state and identifying a target state to capture the effective oscillation frequency Ω ab (N) between those. For Ω ab (N) (for V ab (N)), two different regimes are observed as a function of N: linear and √ N more moderate increases. This state preparation was replaced by electronically coupling the quantum bus to two semi-infinite electrodes. The native quantum transduction process at work in this tunnel junction is not faithfully following the Ω ab (N) variations with N. Due to normalisation to unity of the electronic transparency of the quantum bus and to the low pass filter character of the transduction, large Ω ab (N) cannot be followed by the tunnel junction. At low coupling and when N is small enough not to compensate the small through line coupling, an N 2 power law is preserved for Ω ab (N). The limitations of the quantum transduction in a tunnel junction is pointing how the broadly used concept of electrical contact between a metallic nanopad and a molecular wire can be better described as a quantum transduction process.
Journal of Physical Chemistry Letters, Oct 4, 2019
Bulletin of the American Physical Society, Mar 30, 2013
control in the operation of molecular devices is a key hurdle in the path toward functional synth... more control in the operation of molecular devices is a key hurdle in the path toward functional synthetic devices at the nanoscale. We demonstrate the operation of a molecular rotor whose rotator is decoupled from substrate interactions via a threefold symmetric stator with a single ruthenium atom at its apex, acting as a bearing around which the rotator is controlled. Five "arms" extend from the apex of the stator, one of which is truncated to facilitate observation of device rotations via molecular asymmetry. Molecular rotations are driven via inelastic tunneling electrons from the tip of a scanning tunneling microscope, and the direction of rotation is determined by the choice of electron injection site with respect to the internal molecular structure.
Advances in atom and single molecule machines, 2017
The architecture of single-molecule Boolean logic gates can be based on classical, semi-classical... more The architecture of single-molecule Boolean logic gates can be based on classical, semi-classical, or quantum design rules. The advantages and limitations of each architecture in terms of computing power, clock frequency, and interconnects are discussed together with a complete description of the quantum Hamiltonian computing approach to help for comparison. For all those approaches, the often-mentioned problem of “contact” between a single molecule and a metallic nano-electrode must be re-analyzed in terms of quantum measurements. The metallic nano-electrodes of a tunnel junction is a true measurement apparatus, and its functioning is described by a new transduction function to pass from the intrinsic time-dependent electron transfer to the tunneling current intensity.
Applied Physics Letters, Nov 16, 2015
Journal de physique, Dec 1, 1995
Physical review applied, Mar 9, 2020
Manipulating and coupling molecule gears is the first step towards realizing molecular-scale mech... more Manipulating and coupling molecule gears is the first step towards realizing molecular-scale mechanical machines. Here, we theoretically investigate the behavior of such gears using molecular dynamics simulations. Within a nearly rigid-body approximation we reduce the dynamics of the gears to the rotational motion around the orientation vector. This allows us to study their behavior based on a few collective variables. Specifically, for a single hexa (4-tert-butylphenyl) benzene molecule we show that the rotational-angle dynamics corresponds to the one of a Brownian rotor. For two such coupled gears, we extract the effective interaction potential and find that it is strongly dependent on the center of mass distance. Finally, we study the collective motion of a train of gears. We demonstrate the existence of three different regimes depending on the magnitude of the driving-torque of the first gear: underdriving, driving and overdriving, which correspond, respectively, to no collective rotation, collective rotation and only single gear rotation. This behavior can be understood in terms of a simplified interaction potential.
We have studied the deposition and imaging of nanoscale molecular wheelbarrows. These molecules i... more We have studied the deposition and imaging of nanoscale molecular wheelbarrows. These molecules integrate-in analogy to macroscopic barrows-two wheels, legs and handles along a polyaromatic platform and were imaged on a clean Cu(1 0 0) surface with a scanning tunneling microscope at 7 K. The obtained images are in accordance with calculations and are dominated by the wheels. Several stable conformations of the wheelbarrow were found and identified by comparison with calculated images.
Chemical Physics Letters, 2017
A molecule Boolean 1/2-adder is designed and the XOR and AND truth table calculated at +0.1 V usi... more A molecule Boolean 1/2-adder is designed and the XOR and AND truth table calculated at +0.1 V using 4 graphene electrodes. It functions with level repulsion and destructive interferences effects using 4 molecule electronic states in a quantum Hamiltonian computing approach (QHC) with the abrupt change of the molecular orbital weight of those 4 calculating states as a function of the logical input configuration. The logical inputs enter rotating the two nitro groups of the central board. With QHC, a complex Boolean digital function can be implemented employing the same graphene material for interconnects and the molecule calculating parts.
Advances in atom and single molecule machines, 2012
Advances in atom and single molecule machines, 2020
Nanotechnology, Oct 4, 2018
With a central curved chassis, a four wheels molecule-vehicle was deposited on an Au(111) surface... more With a central curved chassis, a four wheels molecule-vehicle was deposited on an Au(111) surface and imaged at low temperature using a scanning tunneling microscope. The curved conformation of the chassis and the consequent moderate interactions of the four wheels with the surface were observed. The dI/dV constant current maps of the tunneling electronic resonances close to the Au(111) Fermi level were recorded to identify the potential energy entry port on the molecular skeleton to trigger and control a driving of the molecule. A lateral pushing mode of molecular manipulation and the consequent recording of the manipulation signals confirm how the wheels can step by step rotate while passing over the Au(111) surface native herringbone reconstructions. Switching a phenyl holding a wheel to the chassis was not observed for triggering a lateral molecular motion inelastically and without any mechanic push by the tip apex. This points out the necessity to encode the sequence of the required wheel s action on the profile of potential energy surface of the excited states to be able to drive a molecule-vehicle.
HAL (Le Centre pour la Communication Scientifique Directe), 2020
Focused He + beam with a beam diameter lower than 1 nm is heating up the targeted surface for He ... more Focused He + beam with a beam diameter lower than 1 nm is heating up the targeted surface for He + dose larger than 1×10 20 ions/cm 2. The temperature can reach locally 1000 °C resulting in surface decompositions or chemical reactions. This temperature was measured by fabricating gold nano-disk down to 20 nm in diameter and 10 nm in thickness on mica and sapphire surfaces. The melting and vaporization of those nano-disks were used to determine this temperature according to the known gold nanoclusters melting temperature variations as a function of their volume. This local heat production is very negative for precise He + nanolithography resist processes but advantageous without a resist to directly nano-sculpture a nanomaterial when a very thermally conductive support like sapphire is selected.
Bulletin of the American Physical Society, Mar 14, 2017
Springer eBooks, Nov 14, 2022
Springer eBooks, 1993
Preface P.E. Bloechl, A.J. Fisher, C. Joachim. I: Surface physics and self-assembled monolayers. ... more Preface P.E. Bloechl, A.J. Fisher, C. Joachim. I: Surface physics and self-assembled monolayers. 1. Mesoscopic ordering from elastic and electrostatic interactions at surfaces D. Vanderbilt. 2. Chemical potential dependence of surface energetics J.E. Northrup. 3. Surface resistivity and atomic scale friction B.N.J. Persson. 4. Local probe investigation of self-assembled monolayers W. Mizutani, D. Anselmetti, B. Michel. 5. Monte Carlo studies of the microscopic properties of organic thin films J.I. Siepmann, I.R. McDonald. 6. First-principles studies of semiconductor surfaces: reconstruction and dissociative chemisorption I. Stich, M.C. Payne, A. DeVita, M.J. Gillan, L.J. Clarke. II: Aggregates and processes at interfaces. 7. Simulations of materials: clusters and interfacial junctions U. Landman, R.N. Barnett, H.-P. Cheng, C.L. Cleveland, W.D. Luedtke. 8. Stability, structure and melting of copper clusters K.W. Jacobsen, O.H. Nielsen, O.B. Christensen. 9. Structure and dynamics of confined fluids P.A. Thompson, M.O. Robbins, G.S. Grest. 10. Mechanical and electrical properties of metallic contacts A.P. Sutton, T.N. Todorov. III: Chemistry and molecular electron transfer. 11. Molecular and supramolecular self-assembly processes R.A. Bissell, J.F. Stoddart. 12. First-principles calculations of organometallic compounds P. Margl, K. Schwarz, P.E. Bloechl. 13. Electron transport through organic molecules with applications to molecular devices A. Broo. 14. Experimental long-range electron transfer andmolecular switch J.-P. Launay. IV: Scanning probes: STM and AFM. 15. Adsorption and STM imaging of organic molecules from first principles A.J. Fisher, P.E. Bloechl. 16. A continuum model for force microscopy force curve data N.A. Burnham. 17. Moving an adsorbate with the tip apex of a scanning probe microscope: a comparative study of the Xe-Cu(110) and Au-NaCl(100) systems C. Girard, X. Bouju, C. Joachim. 18. Dissociation of individual molecules with a STM G. Dujardin, R.E. Walkup, P. Avouris. V: Mesoscopic electron transport. 19. Computation of quantum-transport properties by random-matrix theory C.W.J. Beenakker. 20. Effect of the electromagnetic environment on single charge tunneling H. Grabert, G.-L. Ingold. 21. Single-electron tunneling through an ultra-small metal particle C. Schoenenberger. 22. Electron transport in open quantum systems W.R. Frensley, C. Fernando, J.R. Hellums, S. Venkata-Narasimhan. Index.
Chemical Physics, Aug 1, 2002
Abstract Observed from the electrodes, the electronic tunnel transport regime though a molecular ... more Abstract Observed from the electrodes, the electronic tunnel transport regime though a molecular wire is described by a generalized non-parabolic dispersion relationship. The calculation of the complex-band structure of a molecular wire leads to an analytical expression for the effective mass m* of a tunneling electron through this wire. m* is calculated for different molecular wires and compared to the ones of standard solid state tunnel junction. In the tunneling regime, the conductance optimization of a molecular wire depends equally on this m* and on its homo–lumo gap.
HAL (Le Centre pour la Communication Scientifique Directe), Jun 28, 2017
HAL (Le Centre pour la Communication Scientifique Directe), Jan 14, 2015
HAL (Le Centre pour la Communication Scientifique Directe), Mar 21, 2016
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Papers by Christian Joachim