Time-Energy Uncertainty Limit for spin-related wavepacket evolution

TL;DR

This paper investigates the quantum transport of spin-related wavepackets in low-dimensional systems, analyzing the time-energy uncertainty relation and its implications for spintronics device design through numerical simulations and theoretical approaches.

Contribution

It introduces a novel analysis of the TEUR in spin-orbit coupled quantum wires using a gedanken experiment and stationary phase method, revealing restrictions on wavepacket evolution and spin splitting effects.

Findings

TEUR applicability verified during wavepacket evolution

Restrictions on incident energy values due to coherence requirements

Observation of spin splitting caused by Rashba spin-orbit interaction

Abstract

In this report we study the quantum transport of charge carriers for low dimensional systems with spin-orbit coupling by means of Heisenberg's inequalities. To develop our analysis, an accurate \emph{gendanken} experiment was carefully put together, mainly based on the spin-field effect transistor phenomenology and taking into account several wide accepted approaches on quantum mechanical limited determinism. While verifying the applicability of time-energy uncertainty relation (TEUR) during electronic wavepacket's evolution through a semiconductor quantum wire, some qualitative information related the dynamic behavior of the system is found. The problem is also approached in the framework of the stationary phase method to guarantee robust coherence for wavepacket's evolution, which lately implies certain restrictions on the incident energy values for the envisioned cases. Tailoring different input parameters such as: incoming particles spin polarization, barrier thickness and Rashba's spin-orbit interaction (R-SOI) strength, we have observed appealing effects while the packet evolves through a quasi-1D heterostructure. Hopefully some of them could be of help in spintronics device designing. We have obtained most of the numerical simulation results, within the so-called conservation zone. However, for certain barrier thicknesses, some values drop into the forbidden area regarding the clear theoretical limit imposed by the TEUR. As an expected bonus throughout our theoretical validation of the TEUR, spin splitting due to finite values of R-SOI was nicely noticed.