High-Fidelity Single-Shot Toffoli Gate via Quantum Control

Area of Science:

• Quantum Computing
• Quantum Information Processing
• Superconducting Circuits

Background:

• The Toffoli gate (controlled-controlled-not) is crucial for universal reversible computing and quantum computation.
• Current Toffoli gate implementations rely on sequential single- and two-qubit gates, leading to lower fidelity and longer operation times.
• A single-shot Toffoli gate is highly desirable for efficient quantum information processing and error correction.

Purpose of the Study:

• To develop a quantum-control procedure for a single-shot Toffoli gate.
• To achieve high fidelity and speed comparable to entangling two-qubit gates.
• To implement the gate using superconducting transmon systems.

Main Methods:

• Utilized a quantum-control procedure for three nearest-neighbor-coupled superconducting transmon systems.
• Employed an enhanced version of the differential evolution algorithm for a nongreedy quantum control strategy.

Main Results:

• Achieved a single-shot Toffoli gate with 99.9% fidelity.
• The gate's speed is comparable to that of an entangling two-qubit gate under realistic conditions.
• Demonstrated a viable method for constructing fast and high-fidelity Toffoli gates.

Conclusions:

• The developed quantum-control procedure enables a high-fidelity, single-shot Toffoli gate.
• This advancement is significant for improving the efficiency of quantum computing and error correction.
• The method offers a faster and more reliable alternative to sequential gate decomposition.