Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session LL03: V: Novel Instrumentation Concepts |
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Sponsoring Units: GIMS Chair: Jie Ma, Shanghai Jiao Tong Univ Room: Virtual Room 3 |
Tuesday, March 21, 2023 5:00AM - 5:12AM |
LL03.00001: Observation of Electron Orbital Signatures of Single Atoms using Atomic Force Microscopy Dingxin Fan Resolving the electronic structure of a single atom bonded within a molecular species is of fundamental importance for understanding and predicting chemical and physical properties. However, the observation of the orbital signature of an individual atom is challenging. We report here the direct identification of two adjacent transition-metal atoms, Fe and Co, within phthalocyanine molecules using noncontact atomic force microscopy (nc-AFM). AFM imaging reveals that the Co atom appears bright and presents four distinct lobes, whereas the Fe atom displays a "square" morphology. Pico-force spectroscopy measurements show a larger repulsion force of about 5 pN on the tip exerted by Co in comparison to Fe. Our combined experimental and theoretical results demonstrate that both the distinguishable features in AFM images and the variation in the measured forces arise from Co's higher electron orbital occupation above the molecular plane. The ability of directly observing orbital signatures using nc-AFM is a promising approach to characterizing the electronic structure of an individual atom in a molecular species. |
Tuesday, March 21, 2023 5:12AM - 5:24AM |
LL03.00002: An electron-spin qubit platform crafted atom-by-atom on a surface Yu Wang Creating a quantum-coherent architecture at the atomic scale has long been an ambition in quantum science and nanotechnology. Here we demonstrate atom-by-atom construction, coherent operations, and readout of coupled electron-spin qubits using a scanning tunneling microscope. To enable the coherent control of “remote” qubits that are outside the tunnel junction, we complement each electron spin with a local magnetic field gradient from a nearby single-atom magnet. Readout is achieved by employing a sensor qubit in the tunnel junction and implementing pulsed double electron spin resonance. Fast single-, two-, and three-qubit operations are thereby demonstrated in an all-electrical fashion. Our work marks the creation of an Angstrom-scale qubit platform, where quantum functionalities using electron spin arrays, built atom-by-atom on a surface, are now within reach. |
Tuesday, March 21, 2023 5:24AM - 5:36AM |
LL03.00003: A millikelvin all-glass scanning probe microscope Chengyuan Huang, Zhenlan Chen, Mengke Ha, Dawei Qiu, Qing Xiao, Zhiyuan Qin, Changjian Ma, Danqing Liu, Haoyuan Wang, Guanglei Cheng Milli-Kelvin scanning probe microscopy (mK-SPM) presents an ongoing experimental challenge due to the intense vibrations[1] in a closed-cycle dilution fridge and the low cooling power available at mK temperatures. A viable approach is to make the system exceptionally rigid and thermally insulative to decouple external vibrations and isolate heat dissipation from the piezo elements. Here we present a low-cost and large scan-area mK-SPM that operates below 100 mK. All the essential parts of our mK-SPM, including the motors, scanners, and microscope body, are made of fused silica glass by taking advantage of its high specific modulus, extremely low thermal expansion coefficient, and excellent thermal insulation properties. We carefully balance the scan area (25 µm×25 µm), heat dissipation, and rigidity of the system to reach optimal performance at mK temperatures. |
Tuesday, March 21, 2023 5:36AM - 5:48AM |
LL03.00004: All-fiber Dilatometer at Cryogenic Temperature and High Magnetic Field Qin Xin In this talk, I will present our recent measurements of thermal expansion coefficient in a variety of materials at cryogenic temperature and high magnetic field. Using all-fiber Michelson interferometer, we are able to resolve pm-level fluctuation of sample thickness induced by AC heating. Data at such accuracy provide new insight into important phase transitions and their coupling to minute crystal structure modifications. |
Tuesday, March 21, 2023 5:48AM - 6:00AM Author not Attending |
LL03.00005: Nonlinear Cantilever AC Magnetometry with Feedback Linear Subtraction Bellave S Shivaram, Victoria R Knight, Ziyuan Wang
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Tuesday, March 21, 2023 6:00AM - 6:12AM |
LL03.00006: Fabricating clean 2D material devices in ultra-high vacuum Mingyan Luo Two-dimensional (2D) materials exhibit a rich set of physical phenomena as a result of reduced dimensionality. Artificial heterostructures based on 2D materials further enrich the physics in flatlands. Most 2D materials are, however, prone to degradation in the presence of trace amount of oxygen or water vapor. Meanwhile, interfacial contamination introduced during the stacking process limits the quality of the heterostructures. To solve these problems, we design and build an ultra-high vacuum (UHV) system in which the entire fabrication process is performed under pressure lower than 5×10-10 mbar. We demonstrate the functionality of this UHV fabrication system by exfoliating various 2D materials with atomically clean surfaces, and in-situ assembling van der Waals heterostructures without interfacial contamination. |
Tuesday, March 21, 2023 6:12AM - 6:24AM |
LL03.00007: Electron Transfer Rate in Nucleotides and Applications in Detection of Genetic Material of SARS-CoV2 Virus. Anil Sharma, Sergio Mendes, Monica Moreno, Aymen Qatamin, Thomas Hulse, Fabricio Campos, Marcelo Pereira, Paulo Roehe, Klester Souza, Leandro Carneiro The charge transport mechanism in DNA, which is yet to be fully understood, has been envisioned as a key component for a wide range of important technologies applications, such as the development of advanced biosensors and of miniaturized bioelectronic circuits. Among major factors to be considered for electrical conductivity properties of DNA are the point of contact between the DNA and the electrode and the environment surrounding a particular DNA strand. We are investigating charge transfer properties in a chain of nucleic acid when chemically bound to a gold surface. For this purpose, we are using redox-active probes and a combination of analytical tools that includes electrochemical modulation of plasmonic surface waves, ac voltammetry, and optical impedance spectroscopy. Such knowledge is providing us a route to develop new biosensing strategies that could eventually detect the genetic code specific to any living being, as for example for the SARS-CoV2 virus. Our current experimental data shows that our technology is capable to detect with high performance target analytes synthesized to mimic specific regions of SARS-CoV2 virus genome. |
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