Quantum Steering and Nonlocal Correlations Between Non-Interacting Delocalized Electrons Under Rashba Spin-Orbit Interaction

This study investigates how Rashba spin-orbit interaction (RSOI) and inter-electron separation influence three distinct quantum resources: Bell nonlocality, quantum steering, and uncertainty-induced nonlocality. The researchers aim to determine if RSOI can be used as a control parameter to stabilize these nonlocal correlations in two-dimensional electron gases (2DEGs), which are promising candidates for scalable, fault-tolerant quantum architectures.

The authors model a two-fermion system within a 2DEG, specifically focusing on the Bi/Ag(111) surface alloy, which is known for its strong RSOI. By constructing the two-fermion density matrix, they analytically derive the three quantum metrics as functions of the Rashba coupling parameter (alpha_R) and the spatial distance (R) between the electrons. The study compares these metrics across varying RSOI strengths to identify regimes where quantum resources are suppressed or enhanced.

The study reveals that while increasing RSOI initially suppresses quantum correlations, this effect is not permanent. All three metrics—Bell nonlocality, quantum steering, and uncertainty-induced nonlocality—exhibit a non-monotonic recovery as the RSOI strength increases, reaching a peak at an optimal coupling of 4.32 x 10^-11 eV m. This suggests that RSOI acts as a critical control knob; by tuning the Rashba interaction via external gate voltages, researchers can effectively manipulate and stabilize nonlocal quantum resources against the natural decay caused by increasing spatial separation between electrons.

As the field of quantum information moves toward scalable, on-chip devices, the ability to control quantum correlations in semiconductor-compatible platforms is essential. This paper demonstrates that 2DEGs, which are already compatible with industry-standard CMOS fabrication, can be engineered to maintain quantum resources through electrical control of spin-orbit coupling. This provides a pathway for developing device-independent quantum protocols in solid-state systems.