Showing 1–3 of 3 results for author: Gee, A

Optomechanical Levitation and Control of High Aspect Ratio Silicon Nanorods

Authors: Zhenan Chen, Sophie Sanghera, Yanhui Hu, James Sabin, Maryam Nikkhou, Alex Gee, David Burt, Qiongyuan Wu, Joseph Kelly, James Millen

Abstract: Nano- and micro-particles levitated by optical, electrical or magnetic fields are a new frontier in precision sensing and for tests of fundamental physics. For optically levitated anisotropic particles it is possible to control their translation, alignment and rotation. We report on the levitation and characterization of nanofabricated, high uniformity, high aspect ratio, high refractive index sil… ▽ More Nano- and micro-particles levitated by optical, electrical or magnetic fields are a new frontier in precision sensing and for tests of fundamental physics. For optically levitated anisotropic particles it is possible to control their translation, alignment and rotation. We report on the levitation and characterization of nanofabricated, high uniformity, high aspect ratio, high refractive index silicon cylinders, with diameters as low as 50 nm and lengths up to 1500 nm. We are able to tune their oscillation frequencies from 10 kHz to over 1 MHz, and exert huge optical torque to generate high rotation rates. These optically levitated silicon nanorods will enable precision torque sensing, and when pushed to smaller sizes, tests of quantum physics through the generation of angular momentum superposition states. △ Less

Submitted 10 August, 2026; v1 submitted 7 August, 2026; originally announced August 2026.

Quantum Interference Enhances the Performance of Single-Molecule Transistors

Authors: Zhixin Chen, Iain M. Grace, Steffen L. Woltering, Lina Chen, Alex Gee, Jonathan Baugh, G. Andrew D. Briggs, Lapo Bogani, Jan A. Mol, Colin J. Lambert, Harry L. Anderson, James O. Thomas

Abstract: An unresolved challenge facing electronics at a few-nm scale is that resistive channels start leaking due to quantum tunneling. This affects the performance of nanoscale transistors, with single-molecule devices displaying particularly low switching ratios and operating frequencies, combined with large subthreshold swings.1 The usual strategy to mitigate quantum effects has been to increase device… ▽ More An unresolved challenge facing electronics at a few-nm scale is that resistive channels start leaking due to quantum tunneling. This affects the performance of nanoscale transistors, with single-molecule devices displaying particularly low switching ratios and operating frequencies, combined with large subthreshold swings.1 The usual strategy to mitigate quantum effects has been to increase device complexity, but theory shows that if quantum effects are exploited correctly, they can simultaneously lower energy consumption and boost device performance.2-6 Here, we demonstrate experimentally how the performance of molecular transistors can be improved when the resistive channel contains two destructively-interfering waves. We use a zinc-porphyrin coupled to graphene electrodes in a three-terminal transistor device to demonstrate a >104 conductance-switching ratio, a subthreshold swing at the thermionic limit, a > 7 kHz operating frequency, and stability over >105 cycles. This performance is competitive with the best nanoelectronic transistors. We fully map the antiresonance interference features in conductance, reproduce the behaviour by density functional theory calculations, and trace back this high performance to the coupling between molecular orbitals and graphene edge states. These results demonstrate how the quantum nature of electron transmission at the nanoscale can enhance, rather than degrade, device performance, and highlight directions for future development of miniaturised electronics. △ Less

Submitted 17 April, 2023; originally announced April 2023.

Comments: 11 pages, 4 figures

Localised Solid-State Nanopore Fabrication via Controlled Breakdown using On-Chip Electrodes

Authors: Jasper P. Fried, Jacob L. Swett, Binoy Paulose Nadappuram, Aleksandra Fedosyuk, Alex Gee, Ondrej E. Dyck, James R. Yates, Aleksandar P. Ivanov, Joshua B. Edel, Jan A. Mol

Abstract: Controlled breakdown has recently emerged as a highly accessible technique to fabricate solid-state nanopores. However, in its most common form, controlled breakdown creates a single nanopore at an arbitrary location in the membrane. Here, we introduce a new strategy whereby breakdown is performed by applying the electric field between an on-chip electrode and an electrolyte solution in contact wi… ▽ More Controlled breakdown has recently emerged as a highly accessible technique to fabricate solid-state nanopores. However, in its most common form, controlled breakdown creates a single nanopore at an arbitrary location in the membrane. Here, we introduce a new strategy whereby breakdown is performed by applying the electric field between an on-chip electrode and an electrolyte solution in contact with the opposite side of the membrane. We demonstrate two advantages of this method. First, we can independently fabricate multiple nanopores at given positions in the membrane by localising the applied field to the electrode. Second, we show we can create nanopores that are self-aligned with complementary nanoelectrodes by applying voltages to the on-chip electrodes to locally heat the membrane during controlled breakdown. This new controlled breakdown method provides a path towards the affordable, rapid, and automatable fabrication of arrays of nanopores self-aligned with complementary on-chip nanostructures. △ Less

Submitted 4 November, 2021; originally announced November 2021.