Spin cross-correlation experiments in an electron entangler
Arunav Bordoloi1,2, Valentina Zannier3, Lucia Sorba3
1Department of Physics, University of Basel, Basel, Switzerland. bordoloi@umd.edu.
Nature
|November 24, 2022
Summary
Researchers directly measured electron spin correlations from Cooper pairs, confirming theoretical predictions of spin-entangled singlet states. This breakthrough enables new nano-electronic spin correlation experiments.
Area of Science:
- Quantum Physics
- Condensed Matter Physics
- Nanotechnology
Background:
- Correlations are crucial for understanding many-body systems but are challenging to measure at the microscopic level, especially for electron spins.
- Theoretically, electrons in a Cooper pair are known to form maximally spin-entangled singlet states, but experimental verification has been lacking.
Purpose of the Study:
- To directly measure spin cross-correlations between electron currents emitted from a Cooper pair splitter.
- To experimentally verify the spin-entangled singlet state of electrons in Cooper pairs.
Main Methods:
- Utilized a Cooper pair splitter device emitting electrons from Cooper pairs.
- Employed ferromagnetic split-gates as tunable spin filters to polarize electron spins in quantum dots.
- Detected spin cross-correlations using standard transport and sensitive transconductance measurements.
Main Results:
- Directly measured negative spin cross-correlation, consistent with spin singlet emission.
- Observed deviations from the ideal value attributed to the overlap of Zeeman-split quantum dot states.
Conclusions:
- Demonstrated a novel method for performing spin correlation experiments in nano-electronic devices.
- The technique is suitable for magnetic field-sensitive superconductors and potential Bell tests with massive particles.
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