Ultrafast gates for single atomic qubits.

Area of Science:

• Quantum Information Science
• Atomic Physics
• Laser Technology

Background:

• Trapped atom hyperfine qubits are promising for quantum computing.
• Achieving fast and high-fidelity single-qubit operations is crucial for scalable quantum systems.
• Ultrafast laser pulses offer potential for rapid manipulation of quantum states.

Purpose of the Study:

• To demonstrate single-qubit operations on a trapped atom hyperfine qubit.
• To utilize a single ultrafast laser pulse for qubit manipulation.
• To achieve gate times significantly shorter than atomic motion periods.

Main Methods:

• Employing a trapped atom hyperfine qubit.
• Using a single, shaped ultrafast pulse from a mode-locked laser.
• Performing a π rotation with precise pulse shaping.

Main Results:

• Achieved single-qubit operations in less than 50 picoseconds.
• Demonstrated population transfer exceeding 99% fidelity.
• Observed negligible spontaneous emission and ac Stark shifts.
• Confirmed interaction deep within the strong excitation regime (Ω(Rabi)/ν(trap)>10(4)).

Conclusions:

• Single ultrafast laser pulses can perform high-fidelity single-qubit operations.
• The demonstrated method is significantly faster than atomic motion, enabling robust quantum gates.
• This approach advances the development of fast and scalable trapped-atom quantum computers.