Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session L66: Fast Electronic Time-Resolved Scanning Probe SpectroscopyInvited
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Sponsoring Units: DCMP Chair: Shawna Hollen, Univ of New Hampshire Room: Four Seasons 1 |
Wednesday, March 4, 2020 8:00AM - 8:36AM |
L66.00001: Actuating and probing a single-molecule switch at femtosecond timescales Invited Speaker: Jascha Repp Accessing ultra-fast non-equilibrium phenomena is enabled by terahertz (THz) scanning tunneling microscopy [1] (THz-STM) through combining STM with lightwave electronics. In THz-STM, the electric field of a phase-stable single-cycle THz waveform acts as a transient bias voltage across an STM junction. These voltage transients may result in a net current that can be detected by time-integrating electronics. The recent development of this lightwave STM has enabled the combined femtosecond and sub-angstrom resolution in observing matter [2]. |
Wednesday, March 4, 2020 8:36AM - 9:12AM |
L66.00002: A Poor Person’s Approach to STM based Pump-Probe and Pulsed-ESR Methods Invited Speaker: Fabian Natterer One major appeal of STM investigations is the unique combination of atomic scale manipulation capabilities with the excellent spectroscopic insight into the electronic structure of 2D materials; providing quasi-static information due to limited preamplifier bandwidth. However, access to the time-domain would enable additional measurement modalities, ranging from the investigation of charge and spin dynamics to the mechanical motion of nanostructures. Despite the early demonstrations by Nunes and Freeman, the widespread implementation of pump-probe methods has remained elusive due to instrumental hurdles. Here we introduce a versatile, straightforward, and affordable setup to achieve nanoseconds time-resolution with minimal changes to an existing STM system [1]. Our setup consists of a dual-channel arbitrary waveform generator, a transfer switch, and a lock-in amplifier. We demonstrate its plug-and-play capability on a field-trip, providing immediate access to the spin-excitation of a magnetic molecule. We further expand our setup to match requirements for pulsed ESR excitations. |
Wednesday, March 4, 2020 9:12AM - 9:48AM |
L66.00003: Single-atom qubits on a surface: pulsed electron spin resonance in a scanning tunneling microscope Invited Speaker: Kai Yang Recently, the ability to drive electron spin resonance (ESR) of individual atoms using a scanning tunneling microscope (STM) provides a major step forward in sensing and manipulating magnetism at the atomic scale. In the first part, I will describe the implementation of continuous-wave ESR in STM [1], which has allowed the measurement of the magnetic interaction between individual atoms [2–5] as well as the detection and control of nuclear spins [6, 7]. Next, I will talk about coherent spin rotations of individual atoms on a surface with control at the nanosecond timescale, using all-electric pulsed ESR in STM. By modulating the atomically-confined magnetic interaction between the STM tip and surface atoms [8, 9], the large oscillating electric field in the STM junction induces quantum Rabi oscillations between spin-up and spin-down states in as little as ~20 nanoseconds [10]. Ramsey fringes and spin echo signals allow us to understand and improve quantum coherence. I will also show the coherent operations on the coupled-spin states of engineered atomic dimers. Coherent control of spins arranged with atomic precision provides a solid-state platform for quantum simulation of many-body systems. |
Wednesday, March 4, 2020 9:48AM - 10:24AM |
L66.00004: Resolving fast dynamics through measurement in the frequency domain Invited Speaker: Riccardo Borgani The advent of multifrequency lock-in amplifiers has made possible the development of AFM methods that are explicitly designed to exploit the nonlinear nature of the tip-surface interaction. These methods capture information in the frequency domain with high signal-to-noise ratio through measurement of intermodulation between two or more drive tones. |
Wednesday, March 4, 2020 10:24AM - 11:00AM |
L66.00005: Synchronizing Atomic-scale Spin and Charge Excitations to Ultrafast Currents Invited Speaker: Sebastian Loth Scanning tunneling microscopy with high frequency signals gives access to ultrafast dynamics in real space on the atomic scale [1, 2]. In order to detect these dynamics, the fast signals must be down converted to low frequencies which inherently requires phase synchronization of the atomic-scale dynamics to the external driving. Here, I will introduce how this synchronization can induce oscillatory modes in the otherwise highly dissipative systems of individual magnetic atoms on conducting surfaces and charge-density waves pinned to atomic defects. |
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