Quantum comput­ing has the poten­tial to provide speedups for classi­cal problems such as complex simula­tion, optimiza­tion and cryptog­ra­phy tasks, but requires scalable and reliable qubit technolo­gies. Semicon­duc­tor spin qubits combine long coher­ence times with estab­lished indus­trial fabri­ca­tion techniques. This project focusses on imple­ment­ing high-fidelity two-qubit gates, which are then expanded to multi-qubit arrays and quanti­fied by apply­ing quantum infor­ma­tion algorithms together with rigor­ous benchmarking.

Compared to other quantum platforms, semicon­duc­tor spin qubits offer the major advan­tages of being able to resort to indus­tri­ally estab­lished fabri­ca­tion methods while still exhibit­ing long coher­ence times in the order of millisec­onds. These features have the poten­tial to serve as a corner­stone for reliable quantum infor­ma­tion process­ing. However, the current main challenge in this field lies in scaling up the number of qubits in a compu­ta­tional device while preserv­ing the qubits’ properties.

In this project, the qubits are defined by single-electron spins confined in silicon quantum dots of Si/SiGe devices. They are indus­tri­ally fabri­cated using CMOS-compat­i­ble processes in collab­o­ra­tion with the semicon­duc­tor research facil­ity IMEC in Belgium. These high-quality devices form the founda­tion for estab­lish­ing high-fidelity two-qubit gates as a first step. Build­ing on this, the archi­tec­ture is going to be expanded to multi-qubit arrays that allow the study of unifor­mity and error propa­ga­tion in larger systems.

The perfor­mance of these devices is not only going to be validated by testing the physi­cal layout but also with basic quantum algorithms. Conse­quently, the algorithms are going to be quanti­fied with rigor­ous bench­mark­ing techniques such as random­ized bench­mark­ing and noise spectroscopy.

By combin­ing indus­trial-grade semicon­duc­tor fabri­ca­tion with optimized control methods, this project directly tackles the challenge of scala­bil­ity in semicon­duc­tor spin-qubits by extend­ing the archi­tec­ture to multi-qubit arrays. In this way, this work is going to contribute to founda­tional steps in the field of quantum technolo­gies with scalable semicon­duc­tor spin-qubit devices.

3D model of a Si/SiGe device with electrons of the spin qubits trapped in quantum dots (Source: https://doi.org/10.1038/s41534-025–01016‑x)