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.