Geometric reduction of dynamical nonlocality in nanoscale quantum circuits

TL;DR

This paper investigates how the geometry of detection schemes in nanoscale quantum circuits influences the preservation or loss of dynamical nonlocality, revealing a new mechanism affecting quantum interference beyond decoherence.

Contribution

It introduces a novel pathway showing that the geometry of detection schemes can intrinsically reduce dynamical nonlocality in quantum systems, supported by experimental and theoretical analysis.

Findings

Geometry of detection schemes impacts dynamical nonlocality.

Loss of nonlocality can occur through local reduction of conduction channels.

Experimental results confirm the geometric influence on quantum interference.

Abstract

Nonlocality is a key feature discriminating quantum and classical physics. Quantum-interference phenomena, such as Young's double slit experiment, are one of the clearest manifestations of nonlocality, recently addressed as $dynamical$ to specify its origin in the quantum equations of motion. It is well known that loss of dynamical nonlocality can occur due to (partial) collapse of the wavefunction due to a measurement, such as which-path detection. However, alternative mechanisms affecting dynamical nonlocality have hardly been considered, although of crucial importance in many schemes for quantum information processing. Here, we present a fundamentally different pathway of losing dynamical nonlocality, demonstrating that the detailed geometry of the detection scheme is crucial to preserve nonlocality. By means of a solid-state quantum-interference experiment we quantify this effect in a diffusive system. We show that interference is not only affected by decoherence, but also by a loss of dynamical nonlocality based on a local reduction of the number of quantum conduction channels of the interferometer. With our measurements and theoretical model we demonstrate that this mechanism is an intrinsic property of quantum dynamics. Understanding the geometrical constraints protecting nonlocality is crucial when designing quantum networks for quantum information processing.