Nuclear spins in semiconductor quantum dots: a many-body quantum system with interesting physics and prospective applications in quantum technologies

Date

Nov 25, 2024

Time

4:30 PM - 5:30 PM

Speaker

Dr. Evgeny Chekhovich

Affiliation

University of Sussex

Series

MPI-PKS Kolloquium

Language

en

Main Topic

Physik

Other Topics

Physik

Description

Epitaxial semiconductor quantum dots (QDs) have long been investigated in the context of quantum physics and quantum information processing (QIP). The solid-state nature of the quantum dots poses many challenges. One such challenge comes from the magnetic moments of the atomic nuclei that make up the crystal lattice of a QD. The dense 3D lattice of the nuclear spins often acts as a source of magnetic noise, limiting quantum coherence of the electron and photon qubits. However, introduction of a new generation of low-strain optically-active GaAs/AlGaAs QDs has shifted the paradigm with recent efforts focused on harnessing nuclear spin magnetism as a testbed for fundamental quantum physics and QIP applications. The advances of the past few years include demonstrations of electron [1] and nuclear [2] spin qubits in a semiconductor quantum dot, as well as reversible transfer of quantum states between electron and nuclear spins [3], offering a pathway to implementation of a solid-state quantum memory. I will discuss recent advanced both in fundamental physics and prospective applications of QD nuclear spins in QIP. Recent findings include an experimental answer to the long-standing dilemma of nuclear spin diffusion in a central-spin model [4]; ferromagnetic ordering of nuclear spin ensembles, with record-high polarisations exceeding 95% [5]; nondemolition measurement of the central electron spin through entanglement with a nuclear spin ensemble [6], which allows for single-shot qubit readout with fidelities exceeding 99.85%. Moreover, we show how strain-engineering of semiconductor lattice can be used to turn the nuclear spin ensemble into an efficient quantum memory, which can store coherent states for very long times, exceeding 100 ms. [1] L. Zaporski et al., Nature Nano 18, 257 (2023) [2] E. A. Chekhovich et al., Nature Nano 15, 999 (2020) [3] M. Appel, et al., arXiv:2404.19680 (2024) [4] P. Millington-Hotze, et al., Nature Comm. 14, 2677 (2023) [5] P. Millington-Hotze, et al., Nature Comm. 15, 985 (2024) [6] H. Dyte et al., Phys. Rev. Lett. 132, 160804 (2024)

Last modified: Nov 21, 2024, 7:40:05 AM