Nagaoka ferromagnetism observed in a quantum dot plaquette.
- Dehollain JP QuTech, TU Delft, Delft, The Netherlands.
- Mukhopadhyay U QuTech, TU Delft, Delft, The Netherlands.
- Michal VP QuTech, TU Delft, Delft, The Netherlands.
- Wang Y Department of Physics, Harvard University, Cambridge, MA, USA.
- Wunsch B Department of Physics, Harvard University, Cambridge, MA, USA.
- Reichl C Solid State Physics Laboratory, ETH Zürich, Zürich, Switzerland.
- Wegscheider W Solid State Physics Laboratory, ETH Zürich, Zürich, Switzerland.
- Rudner MS Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
- Demler E Department of Physics, Harvard University, Cambridge, MA, USA.
- Vandersypen LMK QuTech, TU Delft, Delft, The Netherlands. l.m.k.vandersypen@tudelft.nl.
- 2020-03-04
Published in:
- Nature. - 2020
English
Engineered, highly controllable quantum systems are promising simulators of emergent physics beyond the simulation capabilities of classical computers1. An important problem in many-body physics is itinerant magnetism, which originates purely from long-range interactions of free electrons and whose existence in real systems has been debated for decades2,3. Here we use a quantum simulator consisting of a four-electron-site square plaquette of quantum dots4 to demonstrate Nagaoka ferromagnetism5. This form of itinerant magnetism has been rigorously studied theoretically6-9 but has remained unattainable in experiments. We load the plaquette with three electrons and demonstrate the predicted emergence of spontaneous ferromagnetic correlations through pairwise measurements of spin. We find that the ferromagnetic ground state is remarkably robust to engineered disorder in the on-site potentials and we can induce a transition to the low-spin state by changing the plaquette topology to an open chain. This demonstration of Nagaoka ferromagnetism highlights that quantum simulators can be used to study physical phenomena that have not yet been observed in any experimental system. The work also constitutes an important step towards large-scale quantum dot simulators of correlated electron systems.
- Language
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- English
- Open access status
- green
- Identifiers
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- DOI 10.1038/s41586-020-2051-0
- PMID 32123352
- Persistent URL
- https://sonar.rero.ch/global/documents/238324
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