Effective Hamiltonian for two interacting double-dot exchange-only qubits and their controlled-NOT operations

Abstract

Double-dot exchange-only qubit represents a promising compromise between high speed and simple fabrication in solid-state implementations. A couple of interacting double-dot exchange-only qubits, each composed by three electrons distributed in a double quantum dot, is exploited to realize controlled-NOT (CNOT) operations. The effective Hamiltonian model of the composite system is expressed by only exchange interactions between pairs of spins. Consequently, the evolution operator has a simple form and represents the starting point for the research of sequences of operations that realize CNOT gates. Two different geometrical configurations of the pair are considered, and a numerical mixed simplex and genetic algorithm is used. We compare the nonphysical case in which all the interactions are controllable from the external and the realistic condition in which intra-dot interactions are fixed by the geometry of the system. In the latter case, we find the CNOT sequences for both the geometrical configurations and we considered a qubit system where electrons are electrostatically confined in two quantum dots in a silicon nanowire. The effects of the geometrical sizes of the nanowire and of the gates on the fundamental parameters controlling the qubit are studied by exploiting a spin-density-functional theory-based simulator. Consequently, CNOT gate performances are evaluated.

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Cited by in corpus (8)

• High fidelity resonant gating of a silicon based quantum dot hybrid qubit
• Is all-electrical silicon quantum computing feasible in the long term?
• Coherent Tunneling by Adiabatic Passage of an exchange-only spin qubit in a double quantum dot chain
• High-Fidelity Entangling Gates for Quantum-Dot Hybrid Qubits Based on Exchange Interactions
• Gate fidelity comparison in semiconducting spin qubit implementations affected by control noises
• Coherence time analysis in semiconducting hybrid qubit under realistic experimental conditions
• Controlled-NOT gate sequences for mixed spin qubit architectures in a noisy environment
• Bandwidth-limited and noisy pulse sequences for single qubit operations in semiconductor spin qubits