Quantum coherence and tunneling-controlled spatial localization in a three-level quantum dot system

Abstract

We investigate spatial localization and interference control in a three-level quantum dot (QD) system driven by two-dimensional standing-wave fields. Although QDs are embedded in solid-state environments and are heavier than natural atoms, their discrete energy levels and tunable tunneling couplings allow them to replicate atomic-like behaviors, offering greater flexibility than traditional atomic systems. Using the density matrix formalism, we calculate the optical susceptibility under the influence of a weak probe and a strong control field. This susceptibility explicitly incorporates inter-dot tunneling and phase-coherent interactions, ensuring that the resulting localization is not merely a classical field imprint but reflects quantum interference effects. Our results show that while the standing-wave fields define the spatial modulation template, the accuracy, contrast, and stability of localization are primarily determined by quantum coherence and tunneling-induced interference. Symmetric wavevector configurations lead to sharply confined, isotropic localization profiles, whereas asymmetries in wavevector alignments cause the distribution to broaden and degrade, reducing localization precision. These findings highlight the critical role of tunneling coherence and wavevector alignment in controlling localization behavior. The observations suggest that QDs, with their tunable energy levels and tailored tunneling couplings, provide versatile solid-state analogs for exploring localization phenomena. These systems hold significant potential for applications in spatially resolved quantum information processing, nanoscale sensing, and the development of coherent nanophotonic devices.