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Conductance

About: Conductance is a research topic. Over the lifetime, 8088 publications have been published within this topic receiving 235961 citations.


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Journal ArticleDOI
TL;DR: The results, which are in agreement with the predictions of theoretical models, also clarify the origins of the long-standing discrepancy between the calculated and measured conductance values of 1,4'-benzenedithiol, which often differ by orders of magnitude.
Abstract: The conductance of a single molecule of 1,4'-benzenedithiol bridged between two gold electrodes increases as it is stretched because the energy of the highest occupied molecular orbital is shifted towards the Fermi energy of the electrodes, leading to a resonant enhancement of the conductance.

181 citations

Journal ArticleDOI
TL;DR: The small value of beta demonstrates that conductivity drops off only slowly with chain length, confirming that carotenoid conjugated chains are relatively good molecular "wires".
Abstract: The conductance of carotenoid polyenes chemically bound at each end to gold contacts has been measured for single molecules containing 5, 7, 9, and 11 carbon-carbon double bonds in conjugation. The electronic decay constant, beta, is determined to be 0.22 +/- 0.04 A-1, in close agreement with the value obtained from first principles simulations (0.22 +/- 0.01 A-1). The absolute values of the molecular conductance are within a factor of 3 of those calculated from first principles. The small value of beta demonstrates that conductivity drops off only slowly with chain length, confirming that carotenoid conjugated chains are relatively good molecular "wires".

181 citations

Journal ArticleDOI
TL;DR: In this paper, the authors studied molecular adsorption onto stable metallic nanowires fabricated with an electrochemical method and found that the quantized conductance decreases, typically to a fractional value, which may be attributed to the scattering of the conduction electrons by the adsorbates.
Abstract: We have studied molecular adsorption onto stable metallic nanowires fabricated with an electrochemical method. Upon the adsorption, the quantized conductance decreases, typically, to a fractional value, which may be attributed to the scattering of the conduction electrons by the adsorbates. The further conductance change occurs when the nanowire is exposed to another molecule that has stronger adsorption strength. Because the quantized conductance is determined by a few atoms at the narrowest portion of each nanowire, adsorption of a molecule onto the portion is enough to change the conductance, which may be used for chemical sensors.

181 citations

Journal ArticleDOI
01 Jan 2015-Nature
TL;DR: In this paper, the authors used high-resolution lithography to shape light potentials that realize either a quantum point contact or a quantum wire for atoms, imprinted on a quasi-two-dimensional ballistic channel connecting the reservoirs.
Abstract: Quantized conductance in the transport of neutral atoms is observed in an optically produced channel — either a quantum point contact or a quantum wire — between two atom reservoirs; the lowest non-zero conductance value is the universal conductance quantum, the reciprocal of Planck’s constant. In classical transport theory, a system can adopt any conductance. But in the quantum regime, only discrete steps in the conductance are allowed. This phenomenon, which has been observed in systems with electric charges like metallic junctions or high-mobility electric gases, can conveniently be described using a theory devised by Rolf Landauer in 1957. Tilman Esslinger and colleagues demonstrate quantized conductance in the Landauer regime for neutral matter using a cold atomic gas. In their experiment, a cigar-shaped degenerate fermionic gas is split into two reservoirs connected by a two-dimensional channel, with a quantum point contact that is lithographically projected onto the channel. The high level of control in this cold atomic gas setup allows for tuning crucial parameters including interaction strength and thermalization and might be useful to study exotic phenomena like topological edge states in the future. In transport experiments, the quantum nature of matter becomes directly evident when changes in conductance occur only in discrete steps1, with a size determined solely by Planck’s constant h. Observations of quantized steps in electrical conductance2,3 have provided important insights into the physics of mesoscopic systems4 and have allowed the development of quantum electronic devices5. Even though quantized conductance should not rely on the presence of electric charges, it has never been observed for neutral, massive particles6. In its most fundamental form, it requires a quantum-degenerate Fermi gas, a ballistic and adiabatic transport channel, and a constriction with dimensions comparable to the Fermi wavelength. Here we report the observation of quantized conductance in the transport of neutral atoms driven by a chemical potential bias. The atoms are in an ultraballistic regime, where their mean free path exceeds not only the size of the transport channel, but also the size of the entire system, including the atom reservoirs. We use high-resolution lithography to shape light potentials that realize either a quantum point contact or a quantum wire for atoms. These constrictions are imprinted on a quasi-two-dimensional ballistic channel connecting the reservoirs7. By varying either a gate potential or the transverse confinement of the constrictions, we observe distinct plateaux in the atom conductance. The conductance in the first plateau is found to be equal to the universal conductance quantum, 1/h. We use Landauer’s formula to model our results and find good agreement for low gate potentials, with all parameters determined a priori. Our experiment lets us investigate quantum conductors with wide control not only over the channel geometry, but also over the reservoir properties, such as interaction strength, size and thermalization rate.

179 citations

Journal ArticleDOI
TL;DR: A theoretical treatment of the electrical conductance and tracer permeability of lipid bilayer membranes in the presence of macrocyclic ion carriers is given, showing that some information on the rate constants may be obtained from the existing conductance measurements.

179 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023457
2022828
2021154
2020158
2019172
2018168