# Quantum Interference Supernodes, Thermoelectric Enhancement, and the Role of Dephasing

## TL;DR

This paper investigates how quantum interference supernodes affect thermoelectric properties and how dephasing impacts their robustness, revealing universal scaling rules and the importance of environmental coupling geometry.

## Contribution

It introduces an order-selection rule for supernodes under dephasing and demonstrates how environmental coupling geometry influences coherence loss and thermoelectric response.

## Key findings

- Supernodes are fragile due to parametric suppression with order.
- Incoherent floor dominance leads to universal, order-independent suppression.
- Environmental coupling geometry determines the mechanism of coherence loss.

## Abstract

Quantum interference (QI) can strongly enhance thermoelectric response, with higher-order "supernodes" predicted to yield scalable gains in thermopower and efficiency. A central question, however, is whether such features are intrinsically more fragile to dephasing. Using $B\"uttiker$ voltage-temperature probes, we establish an order-selection rule: the effective near-node order is set by the lowest among coherent and probe-assisted channels. Supernodes are therefore fragile in an absolute sense because their transmission is parametrically suppressed with order. However, once an incoherent floor dominates, the fractional suppression of thermopower, efficiency, and figure of merit becomes universal and order-independent. Illustrating these principles with benzene- and biphenyl-based junction calculations, we show that the geometry of environmental coupling -- through a single orbital or across many -- dictates whether coherence is lost by order reduction or by floor building. These results yield general scaling rules for the thermoelectric response of interference nodes under dephasing.