Operating two exchange-only qubits in parallel

Area of Science:

• Quantum Computing
• Semiconductor Physics

Background:

• Semiconductors and quantum dots are leading platforms for building large-scale quantum computers.
• Precise control of exchange interactions between electrons in quantum dots is crucial for qubit manipulation.
• High-fidelity, concurrent quantum operations are essential to maximize qubit coherence.

Purpose of the Study:

• To demonstrate parallel operation of two exchange-only qubits using six quantum dots.
• To validate the effectiveness of parallel exchange pulse techniques for maintaining qubit control quality.
• To showcase novel quantum gate operations and readout methods for semiconductor qubits.

Main Methods:

• Utilized randomized benchmarking (RB) to assess qubit control during parallel operations.
• Implemented parallel pulse sequences on five barrier gates to modulate exchange interactions.
• Employed cross-entropy benchmarking (XEB) for performance characterization of the quantum system.

Main Results:

• Maximal parallel operation of exchange interactions maintained qubit control quality compared to sequential methods.
• Achieved the first experimental demonstrations of an iSWAP gate for exchange-only qubits.
• Successfully implemented a charge-locking Pauli spin blockade (PSB) readout method.

Conclusions:

• Parallel operation techniques are adaptable to various quantum-dot-based qubit encodings.
• The demonstrated methods enhance the feasibility of scalable quantum computing using semiconductor platforms.
• The study presents significant advancements in controlling and reading out semiconductor qubits.