Gate-based single shot readout of a spin qubit unit cell

Spin-based quantum computing with semiconductor quantum dots holds significant promise, as recent implementations of quantum algorithms have shown. However, the scalability of quantum dot arrays is often constrained by the limitations of charge sensors in terms of sensitivity and footprint. To overcome these challenges, advancing quantum-dot-based architectures requires a shift in the paradigms of charge readout and control.



In this work, we present a 300mm foundry-fabricated spin qubit unit cell which comprises embedded readout and coherent control. We leverage two key techniques: first, we employ gate-based reflectometry to dispersively probe spin states, eliminating the need for external charge sensors. Second, we load a finite number of electrons into a quantum dot array, isolating the array from reservoirs and operating it out of equilibrium. This enables tunable exchange coupling through the manipulation of the confinement potential.



Our qubit unit cell achieves large-visibility single-shot readout of a singlet-triplet qubit, along with two-axis coherent control. Additionally, we demonstrate the operation of this unit cell at elevated temperatures (up to 1 K), where we extract state-of-the-art charge noise levels using free induction decay and dynamical decoupling techniques.



With its integrated readout and low charge noise, this qubit unit cell demonstrates strong potential for scalable quantum computing architectures.