Breakthroughs and New Opportunities Through High-Fidelity Shuttling of Semiconductor Spin Qubits

Spin qubits in semiconductor quantum dots present a promising pathway toward scalable quantum computation, with recent demonstrations of high-fidelity gates. However, connectivity is so far limited to nearest neighbors in a lattice. Transport-based architectures, where qubits are physically shuttled, offer attractive opportunities through reconfigurable connectivity.

This talk presents recent advances in coherent spin shuttling using "conveyor-mode" transport, where traveling-wave potentials move electrons smoothly through a channel. We demonstrate spin transport by back-and-forth shuttling up to 10 μm in total with 99.5% fidelity.

Building on this foundation, I discuss three developments. First, two-qubit operations between spins confined in separate traveling-wave potentials, achieving a ~99% CZ gate fidelity through tunable exchange interaction. Second, operating at lower magnetic fields, single-spin control via resonant conveyor electric-dipole spin resonance or spin-diabatic shuttling through regions with a quantization axis tilt. Third, quantization axis tilts with shuttling velocity control enable switchable two-qubit gates: adiabatic shuttling yields a CZ or SWAP gate, depending on the exchange ramp rate, while diabatic shuttling generates CX through frame changes.