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TT: Fachverband Tiefe Temperaturen

TT 20: Quantum Dots and Quantum Wires (joint session TT/HL)

TT 20.6: Talk

Monday, March 18, 2024, 18:00–18:15, H 3007

Nonmonotonic buildup of spin-singlet correlations in double quantum dot — •Kacper Wrześniewski, Tomasz Ślusarski, and Ireneusz Weymann — Faculty of Physics, Adam Mickiewicz University, Poland

Dynamical buildup of spin-singlet correlations between the two quantum dots is investigated by means of the time-dependent numerical renormalization group method. By calculating the time evolution of the spin-spin expectation value upon a quench in the hopping between the quantum dots, we predict a nonmonotonic buildup of spin-singlet state. In particular, we find that in short timescales the effective exchange interaction between the quantum dots is of ferromagnetic type, favoring spin-triplet correlations, as opposed to the long-time limit, when strong antiferromagnetic correlations develop and eventually an entangled spin-singlet state is formed between the dots. We also numerically determine the relevant timescales and show that the physics is generally governed by the interplay between the Kondo correlations on each dot and exchange interaction between the spins of both quantum dots.

This work was supported by the Polish National Science Centre from funds awarded through decisions No. 2017/27/B/ST3/00621 and No. 2022/45/B/ST3/02826. We also acknowledge the computing time at the Poznan Supercomputing and Networking Center.

[1] K. Wrześniewski, T. Ślusarski, I. Weymann, Rev. B 108 (2023) 144307.

Keywords: quantum dot; Kondo; quantum dynamics