Electron-phonon coupling in metallic carbon nanotubes: Dispersionless electron propagation despite dissipation

Abstract

A recent study [Rosati, Dolcini, and Rossi, Appl. Phys. Lett. 106, 243101 (2015)] has predicted that, while in semiconducting single-walled carbon nanotubes (SWNTs) an electronic wave packet experiences the typical spatial diffusion of conventional materials, in metallic SWNTs its shape remains essentially unaltered up to micrometer distances at room temperature, even in the presence of the electron-phonon coupling. Here, by utilizing a Lindblad-based density-matrix approach enabling us to account for both dissipation and decoherence effects, we test such a prediction by analyzing various aspects that were so far unexplored. In particular, accounting for initial nonequilibrium excitations, characterized by an excess energy E0, and including both intra-and interband phonon scattering, we show that for realistically high values of E0 the electronic diffusion is extremely small and nearly independent of its energetic distribution, in spite of a significant energy-dissipation and decoherence dynamics. Furthermore, we demonstrate that the effect is robust with respect to the variation of the chemical potential. Our results thus suggest that metallic SWNTs are a promising platform to realise quantum channels for the non-dispersive transmission of electronic wave packets.

Lindblad approach to spatiotemporal quantum dynamics of phonon-induced carrier capture processes

“…Although in this work we focus on the low-temperature limit, the proposed equations can easily be extended to finite temperatures. In fact, the original Lindblad approach has already been employed in several room-temperature studies of localized wave packets in various nanosystems and under different scattering mechanisms [34,35,[49][50][51][52], while the carrier capture at finite temperature has been already studied by QK treatments in Refs. [45,53].…”

“…For example, in the concept of flying qubits one could use the shape of a traveling electronic wave packet to store and transmit information around the nanodevice [27][28][29]. Potentially, the carrier capture processes could be able to alter this information in a point which is strongly localized both in space and time [19]; considering the rise of novel materials able to provide strain-tunable QDs [30][31][32][33] or dispersionless propagation [34,35], this property could make the capture processes one key ingredient of electronic-based quantum information protocols.…”

Tracing the nonequilibrium topological state of Chern insulators

“…Exploiting the momentum conservation built into the EL-PH coupling matrix elements, the scattering term can be readily formulated in terms of electron (k) and phonon (q) momenta. As the scattering events are limited to intraband transitions governed by momentum (and energy) conservation, the scattering rates simplify to [45] …”

Energy Dissipation and Decoherence in Solid-State Quantum Devices: Markovian versus non-Markovian Treatments

“…To overcome this severe limitation, a few years ago, an alternative and more general Markov procedure has been proposed [ 19 ]; the latter allows for a microscopic derivation of Lindblad-type scattering superoperators [ 11 ], thus preserving the positive-definite nature of the electronic density matrix. More recently, such an alternative Markov scheme combined with the conventional mean-field approximation has allowed for the derivation of a positive-definite nonlinear equation for the single-particle density matrix [ 20 , 21 ], able to describe both carrier–phonon and carrier–carrier interaction; the latter has been recently applied to the investigation of scattering nonlocality in GaN-based materials [ 22 ] and carbon nanotubes [ 23 ] as well as to the study of carrier capture processes [ 24 , 25 ].…”