High Fidelity Spin Readout in a CMOS Device

Following Moore’s law, CMOS electronics is approaching feature sizes of a few nm. At this size, quantum effects become important, posing challenges to classical computer architecture, while creating new research opportunities for quantum information processing.

One quantum system of strong interest are electron spins in semiconductor quantum dots (QD) used as qubits. Silicon is replacing GaAs as the host material of choice due to its industrial compatibility and superior properties for qubits (small spin orbit coupling and low nuclear spin density). After demonstration of high fidelity quantum gates for such qubits, small spin qubit arrays are the next step towards large scale quantum architectures.

In this presentation, we will show single spin detection in an array of CMOS quantum dots. Reflectometry on a single lead QD, operated at its charge degeneracy point, yields an on-off signal when the charge distribution in neighboring QDs changes. First, we probe charge stability diagrams of different double QD configurations.[i] Second, we perform single shot measurements of spin in a double QD with an avg. readout fidelity of 99% at 100kHz. This result is of prime importance towards the realization of a fast and efficient spin readout required for quantum error correction protocols.