A Spin-Photon Interface Using Charge-Tunable Quantum Dots Strongly Coupled to a Cavity

Area of Science:

• Quantum Information Science
• Solid-State Physics
• Nanotechnology

Background:

• Charged quantum dots are promising solid-state qubits for quantum networks.
• Existing spin-photon interfaces suffer from unstable charge states due to random impurity charging, limiting reflectivity contrast.
• A stable and controllable spin-photon interface is essential for advancing quantum technologies.

Purpose of the Study:

• To demonstrate a robust spin-photon interface using deterministically charged quantum dots.
• To achieve strong coupling between a quantum dot spin and a photonic crystal cavity.
• To enable spin-dependent modulation of cavity reflectivity for quantum applications.

Main Methods:

• Utilizing a diode structure for deterministic charging of quantum dots.
• Integrating the actively charged quantum dot into a photonic crystal cavity.
• Employing optical pumping for spin initialization and measuring spin-dependent cavity reflectivity.

Main Results:

• Achieved strong coupling between the cavity mode and the negatively charged quantum dot state.
• Demonstrated strong spin-dependent modulation of cavity reflectivity with a cooperativity of 12.
• Established a stable and controllable spin-photon interface.

Conclusions:

• Deterministic charging provides a stable platform for quantum dot spin-photon interfaces.
• The demonstrated interface is vital for mediating spin entanglement and photon-photon interactions.
• This work advances quantum networking and distributed quantum computing.