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

TL;DR

This paper proposes a novel method for implementing quantum gates between spin qubits in a triple-dot system with an empty central dot, expanding the possibilities for quantum computing architectures.

Contribution

It introduces a scheme to realize quantum gates outside the usual electron occupancy regime, using a tunable central dot and mapping to a t-J model for analysis.

Findings

High fidelity entangling gates are achievable despite decoherence.

The scheme requires minimal control, only tuning the central dot's potential.

It extends two-qubit gate experiments to triple-dot systems.

Abstract

We propose a scheme for implementing quantum gates and entanglement between spin 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. Our scheme exemplifies the possibility of quantum gates outside the regime where each dot has an electron, so that spin-spin exchange interaction is not the only relevant mechanism. Analytic treatment is possible by mapping the problem to a t-J model. The fidelity of the entangling quantum gate between the spins is analyzed in the presence of decoherence stemming from a bath of nuclear spins, as well as from charge fluctuations. Our scheme provides an avenue for extending the scope of two qubit gate experiments to triple-dots, while requiring minimal control, namely that of the potential of a single dot, and may enhance the qubit separation to ease differential addressability.