Coupling a $^{73}$Ge nuclear spin to an electrostatically defined quantum dot
Paul Steinacker, Gauri Goenka, Rocky Yue Su, Tuomo Tanttu, Wee Han Lim, Santiago Serrano, Tim Botzem, Jesus D. Cifuentes, Shao Qi Lim, Jeffrey C. McCallum, Brett C. Johnson, Fay E. Hudson, Kok Wai Chan, Christopher C. Escott, Andre Saraiva, Chih Hwan Yang, Vincent Mourik, Andrea Morello, Andrew S. Dzurak, Arne Laucht
Published: 2025/10/5
Abstract
Single nuclear spins in silicon are a promising resource for quantum technologies due to their long coherence times and excellent control fidelities. Qubits and qudits have been encoded on donor nuclei, with successful demonstrations of Bell states and quantum memories on the spin-1/2 $^{31}$P and cat-qubits on the spin-7/2 $^{123}$Sb nuclei. Isoelectronic nuclear spins coupled to gate-defined quantum dots, such as the naturally occurring $^{29}$Si isotope, possess no additional charge and allow for the coupled electron to be shuttled without destroying the nuclear spin coherence. Here, we demonstrate the coupling and readout of a spin-9/2 $^{73}$Ge nuclear spin to a gate-defined quantum dot in SiMOS. The $^{73}$Ge nucleus was implanted by isotope-selective ion-implantation. We observe the hyperfine interaction (HFI) to the coupled quantum dot electron and are able to tune it from 180 kHz to 350 kHz, through the voltages applied to the lateral gate electrodes. This work lays the foundation for future spin control experiments on the spin-9/2 qudit as well as more advanced experiments such as entanglement distribution between distant nuclear spins or repeated weak measurements.