Implementing a strand of a scalable fault-tolerant quantum computing fabric

Area of Science:

• Quantum Computing
• Quantum Error Correction

Background:

• The surface code is a leading quantum error correction code due to its favorable error thresholds and nearest-neighbor interactions.
• Efficient parity measurement of code qubits is crucial for surface code operations.

Purpose of the Study:

• To demonstrate high-fidelity parity detection of two code qubits using a third syndrome qubit.
• To deterministically entangle code qubits into specific parity Bell states.

Main Methods:

• Utilized high-fidelity gates to generate entanglement across three superconducting qubits arranged in a lattice.
• Employed a syndrome qubit for parity measurement, conditioned on its state.
• Developed a measurement tomography protocol for characterization.

Main Results:

• Achieved high-fidelity parity detection via syndrome qubit measurement.
• Demonstrated deterministic entanglement of two code qubits into even or odd parity Bell states.
• Successfully characterized the parity readout using measurement tomography.

Conclusions:

• The presented lattice architecture and parity detection method are scalable to larger qubit networks.
• This work outlines a viable path towards achieving fault-tolerant quantum computing.