Tunneling is a fundamental quantum process with no classical equivalent, which can compete with Coulomb interactions to give rise to complex phenomena. Phosphorus dopants in silicon can be placed with atomic precision to address the different regimes arising from this competition. However, they exploit wavefunctions relying on crystal band symmetries, which tunneling interactions are inherently sensitive to. Here we directly image lattice-aperiodic valley interference between coupled atoms in silicon using scanning tunneling microscopy. Our atomistic analysis unveils the role of envelope anisotropy, valley interference and dopant placement on the Heisenberg spin exchange interaction. We find that the exchange can become immune to valley interference by engineering in-plane dopant placement along specific crystallographic directions. A vacuum-like behaviour is recovered, where the exchange is maximised to the overlap between the donor orbitals, and pair-to-pair variations limited to a factor of less than 10 considering the accuracy in dopant positioning. This robustness remains over a large range of distances, from the strongly Coulomb interacting regime relevant for high-fidelity quantum computation to strongly coupled donor arrays of interest for quantum simulation in silicon.
The 2023 Boyer Lecture series is called 'The Atomic Revolution' and is presented by Professor Michelle Simmons AO, a pioneer in atomic electronics and global leader in quantum computing.READ
CQC2T Director Professor Michelle Simmons AO and Chief Investigator Professor Yuerui (Larry) Lui were recognised in the prestigious 2023 Prime Minister’s award ceremony held at Parliament House last nREAD
An international team of researchers has developed a technology that has shattered a world record in continuous variable quantum teleportation. This latest technology offers a viable pathway enroute tREAD
Fault-tolerant, error-corrected quantum computation is commonly acknowledged to be crucial to the realisation of large-scale quantum algorithms that could lead to extremely impactful scientific or comREAD
Engineers show that a jellybean-shaped quantum dot creates more breathing space in a microchip packed with qubits.READ