Quantum computing with quantum dots on quantum linear supports

Motivated by the recently demonstrated ability to attach quantum dots to polymers at well-defined locations, we propose a condensed-phase analog of the ion-trap quantum computer: a scheme for quantum computation using chemically assembled semiconductor nanocrystals attached to a linear support. The linear support is either a molecular string (e.g., DNA) or a nanoscale rod. The phonon modes of the linear support are used as a quantum-information bus between the dots. Our scheme offers greater flexibility in optimizing material parameters than the ion-trap method, but has additional complications. We discuss the relevant physical parameters, provide a detailed feasibility study, and suggest materials for which quantum computation may be possible with this approach. We find that Si is a potentially promising quantum-dot material, already allowing a 5-10-qubit quantum computer to operate with an error threshold of 10(-3).