Addressable electron spin resonance using donors and donor molecules in silicon

Area of Science:

• Quantum Computing
• Solid-State Physics
• Materials Science

Background:

• Phosphorus donors in silicon offer long coherence times and high fidelities for quantum computing.
• Individual addressability of exchange-coupled donors at ~15 nm separation is a significant challenge.

Purpose of the Study:

• To develop a method for individually addressing qubits using exchange-coupled phosphorus donors.
• To leverage distinct hyperfine coupling strengths for qubit addressability.

Main Methods:

• Utilizing atomic precision lithography to position single P donors and 2P molecules.
• Employing hyperfine coupling measurements to differentiate between single donors and donor molecules.
• Conducting atomistic tight-binding simulations and scanning tunneling microscopy.

Main Results:

• Achieved precise placement of a single P donor 16 ± 1 nm from a 2P molecule.
• Observed distinct hyperfine peak separations: 97 ± 2.5 MHz for the single donor and 262 ± 10 MHz for the donor molecule.
• Simulations confirmed strong hyperfine interaction in the 2P molecule with ~0.7 nm interdonor separation.

Conclusions:

• Donor molecules can be utilized for built-in addressability of electron spin qubits in silicon.
• This approach enhances control and scalability for solid-state quantum computing architectures.