Tuning the coherent interaction of an electron qubit and a nuclear magnon

• Published in: arXiv.org 2024-04
• Main Authors: Shofer, Noah, Zaporski, Leon, Martin Hayhurst Appel, Manna, Santanu, Saimon Covre da Silva, Ghorbal, Alexander, Haeusler, Urs, Rastelli, Armando, Claire Le Gall, Gawełczyk, Michał, Atatüre, Mete, Gangloff, Dorian A
• Format: Article
• Language: English
• Subjects: Anisotropy; Coherence; Electron spin; Homogeneity; Magnons; Nuclear interactions; Quantum dots; Qubits (quantum computing); Spectroscopy; Spectrum analysis; Tuning
• ISSN: 2331-8422

A central spin qubit interacting coherently with an ensemble of proximal spins can be used to engineer entangled collective states or a multi-qubit register. Making full use of this many-body platform requires tuning the interaction between the central spin and its spin register. GaAs quantum dots offer a model realization of the central spin system where an electron qubit interacts with multiple ensembles of \(\sim 10^{4}\) nuclear spins. In this work, we demonstrate tuning of the interaction between the electron qubit and the nuclear many-body system in a GaAs quantum dot. The homogeneity of the GaAs system allows us to perform high-precision and isotopically selective nuclear sideband spectroscopy, which reveals the single-nucleus electronic Knight field. Together with time-resolved spectroscopy of the nuclear field, this fully characterizes the electron-nuclear interaction for a priori control. An algorithmic feedback sequence selects the nuclear polarization precisely, which adjusts the electron-nuclear exchange interaction in situ via the electronic g-factor anisotropy. This allows us to tune directly the activation rate of a collective nuclear excitation (magnon) and the coherence time of the electron qubit. Our method is applicable to similar central-spin systems and enables the programmable tuning of coherent interactions in the many-body regime.