Electronic driving of torsional modes in carbon nanotubes via orbital-phonon coupling

Koji Yamada; Wataru Izumida; Mamoru Matsuo; Takeo Kato

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arXiv · 2610.28326

Electronic driving of torsional modes in carbon nanotubes via orbital-phonon coupling

Koji Yamada·Wataru Izumida·Mamoru Matsuo·Takeo Kato

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Abstract

We theoretically investigate electronic driving of a torsional mode in a suspended carbon nanotube quantum dot. The valley states in a nanotube carry opposite orbital magnetic moments along the tube axis, and intervalley mixing forms valley-mixed eigenstates whose splitting can be controlled by an axial magnetic field. We formulate an orbital-rotation coupling between the torsional angular velocity and the valley orbital angular momentum. Using a master equation for sequential tunneling through normal-metal electrodes, we calculate the steady-state current and the phonon distribution of the torsional mode. When the valley-state splitting matches the torsional phonon energy, orbital transitions can drive the mode out of equilibrium. The contacts control both phonon pumping and its electrical readout, allowing substantial excitation with a positive, vanishing, or negative current response. The mechanism requires no intrinsic spin or valley polarization of the electrodes, but uses state-dependent tunneling at the contacts.

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Koji Yamada, Wataru Izumida, Mamoru Matsuo, Takeo Kato. 2026-10-20. Electronic driving of torsional modes in carbon nanotubes via orbital-phonon coupling. https://arxiv.org/abs/2610.28326

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