A two-qubit logic gate in silicon.

Area of Science:

• Quantum Computing
• Solid-State Physics
• Quantum Information Science

Background:

• Scalable quantum computation demands high-fidelity qubits and universal logic gates.
• Existing qubit technologies face challenges in achieving high-fidelity two-qubit gates in solid-state systems suitable for manufacturing.
• Semiconductor systems struggle with qubit coupling and dephasing, limiting their application in quantum computing.

Purpose of the Study:

• To present a novel two-qubit logic gate realized in a silicon quantum dot system.
• To demonstrate the feasibility of high-fidelity two-qubit gates using the exchange interaction in semiconductor qubits.
• To advance the development of scalable and manufacturable quantum computing hardware.

Main Methods:

• Utilizing single spins in isotopically enriched silicon within a quantum dot system.
• Implementing single- and two-qubit operations via the exchange interaction, as proposed by Loss-DiVincenzo.
• Employing direct gate-voltage control for single-qubit addressability and a switchable exchange interaction for controlled-phase gates.
• Performing independent readout of both qubits to verify gate performance.

Main Results:

• Successful realization of CNOT gates through controlled-phase operations and single-qubit manipulations.
• Demonstration of a switchable exchange interaction enabling precise control over two-qubit operations.
• Measurement of clear anticorrelations in two-spin probabilities, confirming the fidelity of the CNOT gate.
• Achieved high-fidelity two-qubit gates in a solid-state system manufacturable via standard lithography.

Conclusions:

• The presented silicon quantum dot system offers a promising platform for scalable quantum computing.
• This work overcomes previous limitations in achieving high-fidelity two-qubit gates in semiconductor-based quantum computers.
• The developed gate technology paves the way for building robust and fault-tolerant quantum processors.