Spin singlet-triplet transition in a Si-based two-electron double quantum dot molecule

TL;DR

This paper demonstrates the magnetic field-induced transition between spin singlet and triplet states in a silicon-based double quantum dot system, confirming theoretical predictions and exploring spin swapping phenomena.

Contribution

First experimental observation of spin singlet-triplet transition in Si double quantum dots using a novel measurement scheme.

Findings

Observed singlet-triplet crossing at various magnetic fields

Results align with theoretical models

First demonstration of spin swapping in such systems

Abstract

We report a successful measurement of the magnetic field-induced spin singlet-triplet transition in silicon-based coupled dot systems. Our specific experimental scheme incorporates a lateral gate-controlled Coulomb-blockaded structure in Si to meet the proposed scheme of Loss and DiVincenzo [1], and a non-equilibrium single-electron tunneling technique to probe the fine energy splitting between the spin singlet and triplet, which varies as a function of applying magnetic fields and interdot coupling constant. Our results, exhibiting the singlet-triplet crossing at a magnetic field for various interdot coupling constants, are in agreement with the theoretical predictions, and give the first experimental demonstration of the possible spin swapping occurring in the coupled double dot systems with magnetic field. *Electronic address: jungchoi@chungbuk.ac.kr [1] D. Loss and D. P. DiVincenzo, Phys. Rev. A 57, 120 (1998).