Transporting, splitting, and connecting spin singlet pairs in a topological pump*

The transport of atoms, electrons or entanglement in general in large many-body systems is becoming an increasingly important target for quantum applications. Often, long-distance qubit connectivity relies on the transport of particles, which leads to unwanted excitations and heating. To circumvent this, we present a ground-state preserving transportation scheme based on periodic modulation of an optical lattice potential. 

In detail, we leverage topological pumping in a periodically modulated one-dimensional optical superlattice to realise the transport of coherent fermionic two-particle states over large distances. Furthermore, we use the macroscopic access of the optical lattice potential to implement gate operations by engineering the local superexchange coupling Jex. More specifically, when two particles meet in a double well of the optical lattice, we can control Jex using two different methods, such that two-particle (SWAP)^n gates are implemented while preserving the motional many-body ground state of the system. We reveal the successful implementation of such gates by observing multi frequency singlet-triplet oscillations (STOs) as a direct signature of entanglement between fermions distributed over tens of lattice sites.