Single-shot parity readout of a minimal Kitaev chain
Abstract
Protecting qubits from noise is essential for building reliable quantum computers. Topological qubits offer a route to this goal by encoding quantum information non-locally, using pairs of Majorana zero modes. These modes form a shared fermionic state whose occupation -- either even or odd -- defines the fermionic parity that encodes the qubit. Crucially, this parity cannot be accessed by any measurement that probes only one Majorana mode. This reflects the non-local nature of the encoding and its inherent protection against noise. A promising platform for realizing such qubits is the Kitaev chain, implemented in quantum dots coupled via superconductors. Even a minimal chain of two dots can host a pair of Majorana modes and store quantum information in their joint parity. Here we introduce a new technique for reading out this parity, based on quantum capacitance. This global probe senses the joint state of the chain and enables real-time, single-shot discrimination of the parity state. By comparing with simultaneous local charge sensing, we confirm that only the global signal resolves the parity. We observe random telegraph switching and extract parity lifetimes exceeding one millisecond. These results establish the essential readout step for time-domain control of Majorana qubits, resolving a long-standing experimental challenge.
Cite
@article{arxiv.2507.01606,
title = {Single-shot parity readout of a minimal Kitaev chain},
author = {Nick van Loo and Francesco Zatelli and Gorm O. Steffensen and Bart Roovers and Guanzhong Wang and Thomas Van Caekenberghe and Alberto Bordin and David van Driel and Yining Zhang and Wietze D. Huisman and Ghada Badawy and Erik P. A. M. Bakkers and Grzegorz P. Mazur and Ramón Aguado and Leo P. Kouwenhoven},
journal= {arXiv preprint arXiv:2507.01606},
year = {2025}
}