Triplet correlations in Cooper pair splitters realized in a two-dimensional electron gas

Area of Science:

• Condensed Matter Physics
• Quantum Information Science
• Materials Science

Background:

• Cooper pairs are fundamental to superconductivity, consisting of entangled electrons.
• Studying Cooper pair spin and entanglement requires spatial separation via Cooper pair splitting (CPS).
• Previous CPS studies were limited, necessitating exploration in new material systems.

Purpose of the Study:

• To demonstrate Cooper pair splitting (CPS) in a semiconductor two-dimensional electron gas (2DEG) for the first time.
• To investigate the spin properties of separated Cooper pairs, including singlet and triplet correlations.
• To establish a scalable platform for on-chip entanglement and topological superconductivity research.

Main Methods:

• Coupling two quantum dots to a superconductor-semiconductor hybrid region.
• Utilizing the semiconductor 2DEG platform with strong spin-orbit interaction.
• Operating quantum dots as spin-filters to analyze electron spin states after splitting.

Main Results:

• Achieved efficient and distinct Cooper pair splitting in the semiconductor 2DEG.
• Observed near-perfect splitting into opposite-spin electrons (singlet pairing).
• Demonstrated splitting into equal-spin electrons, revealing significant triplet correlations due to strong spin-orbit interaction.

Conclusions:

• The first demonstration of CPS in a semiconductor 2DEG offers a novel platform for quantum research.
• The observed strong triplet correlations are a key finding, enabled by the material's spin-orbit interaction.
• This work provides a scalable route towards on-chip entanglement and the creation of artificial Kitaev chains for topological superconductivity.