Anderson Delocalization in Strongly Coupled Disordered Non-Hermitian Chains.

Area of Science:

• Condensed matter physics
• Quantum mechanics
• Wave phenomena

Background:

• Disorder and non-Hermitian effects typically influence wave localization.
• In 1D disordered chains, the non-Hermitian skin effect (NHSE) can cause Anderson delocalization, contradicting standard localization theories.
• While weak disorder preserves NHSE, strong disorder leads to Anderson localization.

Purpose of the Study:

• To investigate the interplay of disorder, non-Hermiticity, and interchain coupling on wave localization.
• To explore Anderson delocalization in a coupled system with antisymmetrically correlated disorder.
• To demonstrate the reemergence of NHSE under specific coupling conditions.

Main Methods:

• Coupling a disordered Hatano-Nelson chain to a disordered Hermitian chain with antisymmetrically correlated disorder.
• Analyzing the system's behavior using a real-space winding number.
• Building and measuring an electrical-circuit analog to experimentally verify findings.

Main Results:

• A critical interchain coupling threshold was identified, leading to Anderson delocalization.
• Anderson delocalization occurs irrespective of disorder strength above this threshold.
• The non-Hermitian skin effect (NHSE) is reinstated, even without a Hermitian counterpart.
• The transition is driven by nonreciprocal hopping, interchain coupling, and engineered disorder correlations.

Conclusions:

• Engineered disorder correlations in coupled non-Hermitian and Hermitian systems can lead to novel delocalization phenomena.
• The study reveals unexplored physics at the intersection of non-Hermiticity and disorder.
• Experimental validation via electrical circuits confirms the reemergence of NHSE.