Year: 2026
Type: article
Abstract: We report on the frequency-dependent terahertz (THz) photoresponse of quantum point contacts (QPCs) operating in the tunneling regime. Although the high-frequency response of QPCs is often attributed to photon-assisted transport, our spectroscopic study across the 0.15–0.7 THz range reveals a complex resonant structure consisting of numerous conductance peaks that are inconsistently sensitive to polarization. We demonstrate that these resonances are independent of the QPC barrier potential but are instead determined by the device geometry. Numerical simulations confirm that these features arise from the excitation of 2D plasmon modes in the surrounding high-mobility two-dimensional electron gas. These resonant plasmonic effects inevitably modulate the QPC response, masking the intrinsic transport physics. Finally, we propose a strategy to isolate the fundamental QPC photoresponse by utilizing lower-mobility—on the order of 104 cm/V s—heterostructures to suppress plasmonic interference, providing a path toward validating theoretical models of high-frequency mesoscopic transport.
Source: Applied Physics Letters
DOI: 10.1063/5.0347196
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W7212074763