Quantum Gates Between Two Spins in a Triple Dot System with an Empty Dot

摘要

We propose a scheme for implementing quantum gates and entanglement betweenspin qubits in the outer dots of a triple-dot system with an empty central dot.The voltage applied to the central dot can be tuned to realize the gate. Ourscheme exemplifies the possibility of quantum gates outside the regime whereeach dot has an electron, so that spin-spin exchange interaction is not theonly relevant mechanism. Analytic treatment is possible by mapping the problemto a t-J model. The fidelity of the entangling quantum gate between the spinsis analyzed in the presence of decoherence stemming from a bath of nuclearspins, as well as from charge fluctuations. Our scheme provides an avenue forextending the scope of two qubit gate experiments to triple-dots, whilerequiring minimal control, namely that of the potential of a single dot, andmay enhance the qubit separation to ease differential addressability.