Probing Quantum Phase Transitions on a Spin Chain with a Double Quantum Dot

TL;DR

This paper proposes a practical method using a double quantum dot coupled locally to a spin chain to efficiently detect quantum phase transitions through entanglement measurements, avoiding complex nonlocal procedures.

Contribution

It introduces a novel local probing technique with a triple quantum dot setup to observe quantum phase transitions in spin chains.

Findings

Demonstrates the feasibility of local entanglement-based QPT detection.

Proposes an experimental setup using singlet projection in triple dots.

Provides a practical alternative to nonlocal entanglement measurements.

Abstract

Quantum phase transitions (QPTs) in qubit systems are known to produce singularities in the entanglement, which could in turn be used to probe the QPT. Current proposals to measure the entanglement are challenging however, because of their nonlocal nature. Here we show that a double quantum dot coupled locally to a spin chain provides an alternative and efficient probe of QPTs. We propose an experiment to observe a QPT in a triple dot, based on the well-known singlet projection technique.