Electrically controlled quantum gates for two-spin qubits in two double quantum dots

TL;DR

This paper presents a theoretical study of exchange-coupled singlet-triplet spin qubits in double quantum dots, focusing on Coulomb interactions, optimal operation points, and dephasing rates relevant for quantum computing.

Contribution

It introduces a charge density operator approach to analyze Coulomb couplings and identifies optimal bias points for qubit operations and idle states.

Findings

Calculated Coulomb couplings between qubits.

Identified optimal bias points for operations.

Estimated dephasing rates due to charge noise.

Abstract

Exchange-coupled singlet-triplet spin qubits in two gate-defined double quantum dots are considered theoretically. Using charge density operators to describe the double-dot orbital states, we calculate the Coulomb couplings between the qubits, and identify optimal bias points for single- and two-qubit operations, as well as convenient idle positions. The same intuitive formulation is used to derive dephasing rates of these qubits due to the fluctuating charge environment, thereby providing the main considerations for a quantum computation architecture that is within current experimental capabilities.