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Argentine School of Micro-Nanoelectronics, Technology and Applications

Quantum Tunnelling Demonstration using a Low-cost Experimental Setup

Carlos González, Juan Ruiz-Rosero, Ruy S. Bonilla, Alba Graciela Avila

Published Oct 8, 2013• 1 citation
OpenAlex

Abstract

A simple and reliable experimental setup that illustrates one-dimensional quantum tunnelling effect is introduced. The main elements in this setup are the fabrication of sharp tips, and the sensing and approaching mechanism. A technique to fabricate very sharp tips is described, with tips made of 60 μm thick tungsten wire easily obtainable from car light bulbs. The technique produced tips with aspect ratios of 2 and tip diameter of 15 nm ±4.5 nm. A mechanical configuration to scale down semi-lineal displacement is suggested along with an experimental setup, including circuitry and measurement.

Related papers

NbTiN SQUID-on-tip fabricated by self-aligned deposition using reactive DC magnetron sputtering

N. Kokubo, B. Gerelkhuu

We fabricate superconducting quantum interference devices (SQUIDs) made of niobium-titanium nitride (NbTiN) thin films on the apex of sharp quartz capillaries. By incorporating reactive DC magnetron sputtering into the self-aligned deposition process for the SQUID-on-tip (SOT) fabrication, we produce NbTiN SOT devices with an effective diameter of ∼100 nm. The ø110 nm device has a superconducting transition temperature of 13.2 K, magnetic flux noise down to 0.7 μΦ0/Hz0.5 (4 K), and operating temperatures of 1.8–10 K. The developed technique enables the synthesis of nitride and other superconductors, thereby expanding the range of materials available for SOT devices.

Applied Physics Letters•Jun 24, 2024•1 citation

Sensing with quantum light: a perspective

Animesh Datta

I present my perspective on sensing with quantum light. I summarise the motivations and methodology for identifying quantum enhancements in sensing over a classical sensor. In the real world, this enhancement will be a constant factor and not increase with the size of the quantum probe as is often advertised. I use a limited survey of interferometry, microscopy and spectroscopy to extract the vital challenges that must be faced to realise tangible enhancements in sensing with quantum light.

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Nanoscale wireframe SQUID on a cantilever by corner lithography

Anonymous, Tim Horstink, Melissa J. Goodwin +5 more

We present the fabrication of nanoscale superconducting quantum interference devices (SQUIDs) at the apex of wireframe tips on self-aligned superconducting cantilever probes. The probes are made on silicon wafers using molding techniques in combination with corner lithography, which results in a nanowire frame tip with a tunable apex structure. A shadow-effect deposition using magnetron sputtering of niobium creates self-aligned superconducting wireframes on cantilevers with accompanying device circuitry. Superconducting weak links are realized at the apex of the wireframes with the use of focused ion beam nanopatterning. The realized SQUIDs have effective diameters ranging from several micrometers down to 100 nm and can be operated in magnetic fields up to 1 T. Furthermore, the nanowires in the wireframe can be used to flux modulate the SQUID locally. This fabrication process enables the production of wafer-scale templates for probes based on on-tip superconducting devices.

arXiv:2601.11331•Physical Review Applied•Aug 28, 2026•0 citations

Quantum Mechanical Tunnelling and Its Applications

D Roy

This book presents a new approach to quantum mechanical tunnelling and its applications to various fields of physics. The conventional concepts of this phenomenon, which are based on a time-dependent or time-independent approach, are inadequate in providing explanations for 1) the limit of resolution of field-emission microscope, 2) the Esaki-Integral representation the tunnelling I-V characteristics of tunnel diodes, 3) the Josephson effect, 4) the tunnelling time, etc. The new theory presented here not only provides adequate explanation for all the above-mentioned effects but also gives an accurate expression for tunnelling current density which predicts results closer to the experimentally observed values. The new presentation also provides a more comprehensive description of the results obtained using older treatment.

WORLD SCIENTIFIC eBooks•Dec 1, 1986•68 citations

Emergent chirality in multilead Luttinger-liquid junctions out of equilibrium

D. N. Aristov, I. V. Gornyi, Dmitry G. Polyakov +1 more

We study charge transport through $N$-lead junctions ($N\ensuremath{\ge}3$) of spinless Luttinger-liquid wires with bias voltages applied to Fermi-liquid reservoirs. In particular, we consider a Y junction, which is a setup characteristic of the tunneling experiment. In this setup, the strength of electron-electron interactions in one of the arms (``tunneling tip'') is different from that in the other two arms (which form together the ``main wire''). For a generic single-particle $S$ matrix of the junction, we find that the bias voltage $V$ applied, even symmetrically, to the main wire generates a current proportional to $|V|$ in the tip wire. We identify two mechanisms of this nonequilibrium-induced ``emergent chirality'' in a setup characterized by the time-reversal- and parity-symmetric Hamiltonian of the junction. These are (i) the emergence of an effective magnetic flux, which breaks time-reversal symmetry, and (ii) the emergence of parity-breaking asymmetry of the setup, both proportional to the interaction strength and the sign of the voltage. The current in the tip wire generated by mechanism (i) is reminiscent of the Hall current in the linear response of a system the Hamiltonian of which breaks time-reversal symmetry; however, in the absence of any magnetic field or a local magnetic moment. Similarly, mechanism (ii) can be thought of as an emergent ``photogalvanic effect,'' however, in the presence of inversion symmetry within the main wire. The nonequilibrium chirality implies a rectification of the current in the tip when the main wire is biased by ac voltage.

arXiv:1907.08034•Physical review. B./Physical review. B•Oct 10, 2019•1 citation

Experimental Methods in Quantum Optics Experiments

Warit Asavanant, Akira Furusawa

In this appendix, we explain some of the basic experimental techniques used in the quantum optics experiment. This section is meant for the readers to grasp the image of the experimental development and demonstration of the optical quantum computer

•Jan 1, 2022•0 citations
A simple and reliable experimental setup that illustrates one-dimensional quantum tunnelling effect is introduced. The main elements in this setup are the fabrication of sharp tips, and the sensing and approaching mechanism. A technique to fabricate very sharp tips is described, with tips made of 60 μm thick tungsten wire easily obtainable from car light bulbs. The technique produced tips with aspect ratios of 2 and tip diameter of 15 nm ±4.5 nm. A mechanical configuration to scale down semi-lineal displacement is suggested along with an experimental setup, including circuitry and measurement.
We fabricate superconducting quantum interference devices (SQUIDs) made of niobium-titanium nitride (NbTiN) thin films on the apex of sharp quartz capillaries. By incorporating reactive DC magnetron sputtering into the self-aligned deposition process for the SQUID-on-tip (SOT) fabrication, we produce NbTiN SOT devices with an effective diameter of ∼100 nm. The ø110 nm device has a superconducting transition temperature of 13.2 K, magnetic flux noise down to 0.7 μΦ0/Hz0.5 (4 K), and operating temperatures of 1.8–10 K. The developed technique enables the synthesis of nitride and other superconductors, thereby expanding the range of materials available for SOT devices.
We present the fabrication of nanoscale superconducting quantum interference devices (SQUIDs) at the apex of wireframe tips on self-aligned superconducting cantilever probes. The probes are made on silicon wafers using molding techniques in combination with corner lithography, which results in a nanowire frame tip with a tunable apex structure. A shadow-effect deposition using magnetron sputtering of niobium creates self-aligned superconducting wireframes on cantilevers with accompanying device circuitry. Superconducting weak links are realized at the apex of the wireframes with the use of focused ion beam nanopatterning. The realized SQUIDs have effective diameters ranging from several micrometers down to 100 nm and can be operated in magnetic fields up to 1 T. Furthermore, the nanowires in the wireframe can be used to flux modulate the SQUID locally. This fabrication process enables the production of wafer-scale templates for probes based on on-tip superconducting devices.
This book presents a new approach to quantum mechanical tunnelling and its applications to various fields of physics. The conventional concepts of this phenomenon, which are based on a time-dependent or time-independent approach, are inadequate in providing explanations for 1) the limit of resolution of field-emission microscope, 2) the Esaki-Integral representation the tunnelling I-V characteristics of tunnel diodes, 3) the Josephson effect, 4) the tunnelling time, etc. The new theory presented here not only provides adequate explanation for all the above-mentioned effects but also gives an accurate expression for tunnelling current density which predicts results closer to the experimentally observed values. The new presentation also provides a more comprehensive description of the results obtained using older treatment.
We study charge transport through NNN-lead junctions ($N\ensuremath{\ge}3$) of spinless Luttinger-liquid wires with bias voltages applied to Fermi-liquid reservoirs. In particular, we consider a Y junction, which is a setup characteristic of the tunneling experiment. In this setup, the strength of electron-electron interactions in one of the arms (``tunneling tip'') is different from that in the other two arms (which form together the ``main wire''). For a generic single-particle SSS matrix of the junction, we find that the bias voltage VVV applied, even symmetrically, to the main wire generates a current proportional to ∣V∣|V|∣V∣ in the tip wire. We identify two mechanisms of this nonequilibrium-induced ``emergent chirality'' in a setup characterized by the time-reversal- and parity-symmetric Hamiltonian of the junction. These are (i) the emergence of an effective magnetic flux, which breaks time-reversal symmetry, and (ii) the emergence of parity-breaking asymmetry of the setup, both proportional to the interaction strength and the sign of the voltage. The current in the tip wire generated by mechanism (i) is reminiscent of the Hall current in the linear response of a system the Hamiltonian of which breaks time-reversal symmetry; however, in the absence of any magnetic field or a local magnetic moment. Similarly, mechanism (ii) can be thought of as an emergent ``photogalvanic effect,'' however, in the presence of inversion symmetry within the main wire. The nonequilibrium chirality implies a rectification of the current in the tip when the main wire is biased by ac voltage.