Putting a new spin on 100 years of spin: Optimal control-driven quantum spin engineering
Researcher from the Danish Center for Ultrahigh-Field NMR Spectroscopy contributes to marking 100 years of spin with a review in a special issue of Science Advances. From basic quantum mechanics to optimal control theory, the review explores how increasingly sophisticated approaches can be used to control and manipulate spins.
Professor Niels Chr. Nielsen, in collaboration with researchers from the Technical University in Munich, Freie Universität Berlin, University of Bourgogne Europe, and the Technical University in Dortmund, has reviewed optimal control of spin systems. The review traces the development from the first experimental manipulation of nuclear spins to the establishment of highly efficient numerical optimisation techniques and analytical methods based on what is known as Optimal Control Theory.
“It is fascinating to see how far the field has come in 100 years. What began as a new and rather puzzling concept in quantum mechanics has developed into a field where we can manipulate spin systems with remarkable precision. In the review, we look back at the developments that have made this possible and at the role optimal control has played along the way,” says Professor Niels Chr. Nielsen.
Using optimal control as mathematical framework, highly sophisticated nuclear-spin experiments have been developed in magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR). Looking ahead, the review highlights the emerging connection between concepts from quantum optimal control and machine learning, pointing towards promising initial research in this direction. Understanding how increasingly complex quantum systems can be controlled in the best possible way, as well as where the fundamental limits of such control lie, remains a central challenge for quantum science and technology.
Congratulations to Niels Chr. and co-authors on the publication.
Spin in a nutshell
Spin is a fundamental property of particles such as electrons and atomic nuclei. It is a quantum mechanical property that, among other things, makes atoms behave somewhat like tiny magnets.
First introduced in 1925, the concept of spin fundamentally changed our understanding of matter. Today, the ability to observe and control spin is at the heart of technologies ranging from NMR spectroscopy and medical imaging to emerging quantum technologies.
When placed in a magnetic field, spins can interact with the field and be manipulated using electromagnetic pulses. By carefully controlling these interactions, researchers can extract detailed information about the structure and behaviour of molecules and materials. Increasingly precise control of spin is also opening new possibilities in areas such as quantum sensing, quantum computing and other emerging quantum technologies.