Quantum Coulomb drag signatures of Majorana bound states

TL;DR

This paper proposes a theoretical method using drag transport in double quantum dots to identify Majorana bound states unambiguously, highlighting distinctive symmetric split peaks in transconductance as a signature.

Contribution

It introduces a novel nonlocal transport probe based on drag transconductance to distinguish Majorana bound states from trivial states in solid-state systems.

Findings

Pronounced split peaks in drag transconductance indicate MBS presence.

Symmetric and characteristic peak splitting differentiates MBS from trivial states.

Quantum coherence dynamics correlate with MBS-induced features.

Abstract

Majorana bound states (MBSs), with their non-Abelian statistics and topological protection, are key candidates for fault-tolerant quantum computation. However, their unambiguous identification in solid-state systems remains a fundamental challenge. Here, we present a theoretical study demonstrating that drag transport in a capacitively coupled double quantum dot system offers a robust and nonlocal probe of weakly coupled MBSs. Using the master equation approach, we investigate both steady-state and transient dynamics and uncover a distinctive signature of MBSs, namely the emergence of pronounced split peaks in the drag transconductance, directly linked to inter-MBS coupling. We further show that the dynamics of quantum coherence is correlated with the emergence and enhancement of MBS-induced split peaks in the drag transconductance. A comparative analysis with trivial subgap states reveals key differences, that is, MBS-induced transconductance peaks are symmetric and exhibit characteristic splitting, while trivial-state features are generally asymmetric and lack such robust splitting behavior. These findings establish experimentally accessible criteria for distinguishing MBSs from trivial subgap states and provide a practical framework for probing Majorana physics through nonlocal transport.