A trapped-ion-based quantum byte with 10(-5) next-neighbour cross-talk

Area of Science:

• Quantum Information Science
• Atomic Physics
• Quantum Computing Hardware

Background:

• Scalable quantum computing requires precise control over individual qubits within a quantum register.
• Executing single-qubit gates can induce unwanted errors (cross-talk) in other qubits, hindering fidelity and scalability.
• Quantum error correction protocols are essential for fault-tolerant quantum computing but are sensitive to cross-talk levels.

Purpose of the Study:

• To demonstrate individual qubit addressing within a quantum byte (eight qubits).
• To quantify the cross-talk error induced in non-addressed qubits during single-qubit gate operations.
• To assess if the measured cross-talk is below the threshold for efficient fault-tolerant quantum computing.

Main Methods:

• Implementation of a quantum byte using microwave-driven hyperfine qubits of ytterbium-171 ions.
• Confinement of ions in a Paul trap enhanced with a magnetic gradient field for qubit manipulation.
• Measurement of cross-talk errors on non-addressed qubits following single-qubit gate applications.

Main Results:

• Successful demonstration of addressing individual qubits within an eight-qubit quantum register.
• Quantified cross-talk errors to be on the order of 10^-5.
• Achieved cross-talk levels significantly below the established threshold for fault-tolerant quantum computing.

Conclusions:

• The developed method overcomes the scalability limitations imposed by cross-talk errors in quantum registers.
• The results pave the way for building more robust and scalable quantum computers.
• This work contributes to the practical realization of fault-tolerant quantum computation through precise qubit control.