Distributed Entanglement and Qubit Shuttling: Advancing Scalable Quantum Architectures in Germanium

Semiconductor quantum processors have the potential to scale to modular quantum computers, in which qubit registers are coupled by quantum links, enabling high-connectivity and space for control circuitry [1,2]. Over the years, individual spin-qubit registers have progressed to two-dimensional systems demonstrating high-fidelity operations and the execution of small quantum algorithms [3,4]. Meanwhile, spin shuttling has been demonstrated in linear channels and is additionally used to perform single and two-qubit gates operations [5,6].

In this talk, we discuss the new opportunities opened by hole spin shuttling in germanium heterostructures. A peculiar emphasis is laid on the realization of a shared-control shuttling link integrated between distant qubit registers, enabling the first demonstration of quantum entanglement in a rudimentary modular quantum processor amde of spins. Combining local qubit operation with coherent shuttling, we generate Bell states formed by spins residing in separate registers and prove entanglement between distant qubit registers by quantum state tomography [7].

[1] Taylor, J. et al., Nat. Phys., 1, 117-183 (2005)

[2] Vandersypen, L. M. K. et al., npj Quant. Inf., 3, 34 (2017)

[3] George, H. C. et al., Nano. Lett., 25, 793-799 (2025)

[4] Ha, S. D. et al., PRX Quantum, 6, 030327 (2025)

[5] Wang, C.-A. et al., Science, 385, 447-452 (2024)

[6] Matsumoto, Y. and De Smet M., et al., arXiv (2025)

[7] Ademi, Z. et Bassi, M. et al., arXiv (2025)