Coherent transport of spin by adiabatic passage in quantum dot arrays*

The coherent transport of spin in arrays of quantum dots is important for distributing quantum information, or realizing more efficient spin-readout, across the array. A natural strategy to achieve charge transport in quantum dot arrays is known as coherent transport by adiabatic passage (CTAP). The simplicity of this method motivates the search for spin-based analogs of CTAP (spin-CTAP) that may allow robust spin transport. We develop the theoretical framework of spin-CTAP using the Heisenberg exchange interaction in a linear array of quantum dots. Applying an AC exchange modulation according to CTAP pulse sequences allows adiabatic spin-transfer across arbitrarily large arrays of dots. By choosing a staggered static exchange profile, we can ensure that only certain spin configurations realize the transfer protocol across the array, while other states are blocked from spin-CTAP. We show how to use this feature to generate arbitrarily large Greenberger-Horne-Zeilinger (GHZ) states in the system. Our transfer and entanglement generation protocols are immediately applicable to current experiments in quantum dot arrays.