Spin Filtering and Entanglement Swapping through Coherent Evolution of a Single Quantum Dot

TL;DR

This paper presents a method using the dynamics of electrons in a quantum dot for spin measurement, entanglement swapping, and quantum state generation, with robustness to various errors and decoherence.

Contribution

It introduces a coherent evolution approach for spin filtering and entanglement swapping in quantum dots, supported by analytic and numerical validation.

Findings

Effective charge-spin Hamiltonian matches numerical results.

Method is robust to dot size, initialization errors, and hyperfine decoherence.

Demonstrates potential for quantum computation resources.

Abstract

We exploit the non-dissipative dynamics of a pair of electrons in a large square quantum dot to perform singlet-triplet spin measurement through a single charge detection and show how this may be used for entanglement swapping and teleportation. The method is also used to generate the AKLT ground state, a further resource for quantum computation. We justify, and derive analytic results for, an effective charge-spin Hamiltonian which is valid over a wide range of parameters and agrees well with exact numerical results of a realistic effective-mass model. Our analysis also indicates that the method is robust to choice of dot-size and initialization errors, as well as decoherence introduced by the hyperfine interaction.