Atomic scale coherent manipulation of the electron spin in semiconductors

Informazioni relative al progetto

OneSPIN

ID dell’accordo di sovvenzione: 101075855

DOI

10.3030/101075855

Data della firma CE 9 Marzo 2023

Data di avvio 1 Gennaio 2024

Data di completamento 31 Dicembre 2028

Finanziato da

• European Research Council (ERC)

Costo totale

€ 1 913 122,50

Contributo UE

€ 1 913 122,50

Coordinato da

ECOLE POLYTECHNIQUE
France

Periodic Reporting for period 1 - OneSPIN (Atomic scale coherent manipulation of the electron spin in semiconductors)

Periodo di rendicontazione: 2024-01-01 al 2026-06-30

Sintesi del contesto e degli obiettivi generali del progetto

Quantum technologies aim to exploit fundamental quantum properties to enable new approaches to information processing, secure communication and sensing. In this context, the electron spin is a particularly promising quantum degree of freedom, as it naturally forms a two-level system, can be manipulated rapidly, and can be coupled to light. Achieving coherent control of individual electron spins in solid-state systems is therefore a central challenge for the development of future quantum technologies.

Recent advances in two-dimensional (2D) semiconductors have opened new opportunities in this field. Atomically thin materials such as transition-metal dichalcogenides host optically active point defects that can emit single photons and confine electronic states at the atomic scale. These properties make them attractive candidates for spin–photon interfaces and scalable quantum devices. However, the microscopic nature of many of these defect states remains poorly understood, and their spin coherence properties are still largely unexplored.

A key limitation is the lack of experimental tools capable of simultaneously probing the atomic structure of a defect, its electronic and optical properties, and the coherence of its spin state. Existing approaches typically access only part of this information, preventing a full understanding of how the local environment governs quantum coherence and limiting the ability to engineer robust spin qubits.

The OneSPIN project addresses this challenge by developing a novel experimental platform that combines local-probe techniques with optical detection of spin resonance. Its objective is to enable the initialization, manipulation and readout of individual electron spins while resolving their atomic and electronic environment with high precision. By focusing on 2D semiconductors—materials that are chemically stable and entirely surface-based—the project aims not only to probe single spins, but also to engineer their environment by controlling charge states and the position of atomic defects. In the longer term, OneSPIN is expected to advance fundamental understanding of spin coherence in low-dimensional materials and to contribute to the development of future semiconductor-based quantum technologies.

Lavoro eseguito dall’inizio del progetto fino alla fine del periodo coperto dalla relazione e principali risultati finora ottenuti

During the first reporting period, the main effort was devoted to the construction of a completely new experimental infrastructure dedicated to the project, alongside the recruitment and establishment of the research team. A state-of-the-art cryogenic optical setup was successfully installed and brought into operation, achieving temperatures below 4 K. This platform provides full control of optical excitation and detection, including polarization control, spectral analysis, single-photon detection and photon correlation measurements.

A key technological achievement was the integration of strong and versatile magnetic-field capabilities, combining static magnetic fields up to one tesla with radiofrequency magnetic fields delivered through custom-designed coplanar waveguides. These elements were validated through successful detection of spin-resonance signals in reference systems, confirming their suitability for future single-spin experiments.

In parallel, a custom scanning tunnelling microscope was developed for future integration into the cryogenic optical environment. This unique instrument will enable high-resolution electronic measurements together with efficient optical collection, a combination that represents a significant experimental milestone. The microscope was successfully tested at cryogenic temperatures, confirming a proper thermalisation and full functionality of its mechanical and electrical components.

To support complex and long-duration experiments, a fully automated measurement and control software was developed. This unified interface allows simultaneous control of more than twenty experimental devices and enables unattended operation over extended periods, which is essential for high-precision quantum measurements.

On the scientific side, the project achieved important early results. A new method was developed to generate isolated single-photon emitters in monolayer tungsten disulfide by controlled high-temperature thermal annealing. This approach led to the observation of sharp optical emission lines and clear single-photon behaviour. In addition, long-lived spin signals of resident electrons in the same material were detected optically, opening the door to future experiments on optical detection of spin resonance at the single-defect level

Progressi oltre lo stato dell’arte e potenziale impatto previsto (incluso l’impatto socioeconomico e le implicazioni sociali più ampie del progetto fino ad ora)

The project aims to go beyond the current state of the art, both technologically and scientifically. The integration of high-efficiency optical detection within a scanning tunnelling microscope operating at liquid-helium temperatures would represent a major step forward, as it enables simultaneous access to atomic-scale structure, electronic properties and optical emission. This capability addresses a long-standing experimental barrier in the study of low-dimensional semiconductors.

The demonstration of a thermally activated and controllable method for generating single-photon emitters in two-dimensional materials provides a new and broadly applicable route to engineer quantum light sources. Unlike previously used techniques, this approach relies on controlled thermal annealing at the micrometer scale and can be extended to a wide range of layered semiconductors.

Looking ahead, further progress will require the continued optimisation of radiofrequency coupling at higher frequencies, the reduction of mechanical vibrations, and the precise identification of the microscopic origin of the observed quantum emitters. The platform developed in this project is well positioned to address these challenges. In the longer term, the results are expected to enable new experiments on single-spin coherence and control, fostering further research and paving the way for future applications in quantum technologies based on scalable solid-state system