Low-noise conditional operation of singlet-triplet coupled quantum dot qubits

TL;DR

This paper analyzes how charge noise affects singlet-triplet quantum dot qubits and identifies device configurations that minimize noise impact, enabling faster and more reliable quantum gates.

Contribution

It provides a detailed theoretical framework for understanding charge noise effects and predicts optimal device geometries for low-noise quantum gate operation.

Findings

Existence of noise-immune sweet spots depends on device geometry.

Analytical and numerical identification of optimal conditions for low-noise gates.

Demonstration of alternative optimal configurations beyond traditional sweet spots.

Abstract

We theoretically study the influence of charge noise on a controlled phase gate, implemented using two proximal double quantum dots coupled electrostatically. Using the configuration interaction method, we present a full description of the conditional control scheme and quantitatively calculate the gate error arising from charge fluctuations. Our key finding is that the existence of noise-immune sweet spots depends on not only the energy detuning but also the device geometry. The conditions for sweet spots with minimal charge noise are predicted analytically and verified numerically. Going beyond the simple sweet-spot concept we demonstrate the existence of other optimal situations for fast and low-noise singlet-triplet two-qubit gates.