Using Photoexcited Core/Shell Quantum Dots To Spin Polarize Appended Radical Qubits

Area of Science:

• Materials Science
• Quantum Physics
• Chemistry

Background:

• Semiconductor quantum dots (QDs) offer tunable spin properties for quantum information science.
• Rapid spin relaxation in colloidal QDs hinders their application in quantum technologies.
• Organic molecules appended to QDs can potentially store spin information.

Purpose of the Study:

• To develop a method for generating long-lived spin polarization in organic molecules using photoexcited quantum dots.
• To investigate the influence of QD shell thickness and ligand density on spin polarization dynamics.
• To explore the potential of QD-organic hybrid systems as spin qubits for quantum information applications.

Main Methods:

• Synthesis of CdSe/CdS core/shell quantum dots covalently linked to naphthalenediimide (NDI) ligands.
• Investigation of photoinduced electron transfer dynamics using varying shell thicknesses and NDI molecule numbers.
• Utilizing transient Electron Paramagnetic Resonance (EPR) spectroscopy to probe spin polarization.

Main Results:

• Photoexcited QDs effectively induce long-lived spin polarization in the appended NDI radical anion.
• Electron transfer dynamics are modulated by QD shell thickness and the number of NDI ligands per QD.
• Observed spin polarization is explained by radical pair and triplet mechanisms.

Conclusions:

• This study demonstrates a novel approach to harness QD photoexcitation for robust spin polarization of organic molecules.
• The developed QD-NDI system shows promise for creating spin qubits with extended coherence times.
• This work paves the way for advanced quantum information processing using hybrid QD-organic systems.