Scalable Improvement of the Generalized Toffoli Gate Realization Using Trapped-Ion-Based Qutrits.

Area of Science:

• Quantum Information Science
• Atomic Physics
• Quantum Computing

Background:

• The Toffoli gate is essential for quantum algorithms but challenging to implement efficiently.
• Current methods require many two-qubit gates or ancilla qubits, limiting scalability on noisy intermediate-scale quantum (NISQ) devices.

Purpose of the Study:

• To experimentally demonstrate a scalable N-qubit Toffoli gate improvement.
• To explore the use of qutrits (three-level quantum systems) for efficient Toffoli gate implementation.
• To compare qutrit-based and standard qubit-based Toffoli gate decompositions.

Main Methods:

• Utilized ^{171}Yb^{+} trapped-ion-based optical-metastable-ground encoded qutrits.
• Employed the Mølmer-Sørensen gate as the fundamental entangling operation.
• Implemented a qutrit-based Toffoli gate decomposition using upper qutrit levels as ancillae.

Main Results:

• Successfully demonstrated a scalable N-qubit Toffoli gate for N up to 10.
• The qutrit approach simplifies experimental implementation with global control of ancilla levels.
• Showcased increased accuracy in a three-qubit Grover's search by mitigating leakage errors.

Conclusions:

• The qutrit-based Toffoli gate offers a scalable and experimentally simpler alternative for quantum computing.
• This approach addresses resource limitations in NISQ devices, paving the way for more complex quantum algorithms.