High-Fidelity Trapped-Ion Quantum Logic Using Near-Field Microwaves

Area of Science:

• Quantum computing
• Atomic physics
• Surface ion traps

Background:

• High-fidelity two-qubit gates are essential for scalable quantum computation.
• Surface ion traps offer a promising platform for miniaturized quantum processors.
• Controlling qubits in the presence of environmental noise remains a challenge.

Purpose of the Study:

• To demonstrate a high-fidelity two-qubit logic gate using near-field microwaves.
• To implement a dynamically decoupled gate for improved qubit stability.
• To create entangled Bell states with ^{43}Ca^{+} hyperfine qubits.

Main Methods:

• Utilized a room-temperature microfabricated surface ion trap.
• Employed a dynamically decoupled gate method to mitigate energy shifts.
• Applied microwaves via an integrated electrode to generate oscillating magnetic field gradients.
• Used ^{43}Ca^{+} hyperfine "atomic clock" qubits with long coherence times (T_{2}^{*}≈50 s).

Main Results:

• Achieved a two-qubit logic gate driven by near-field microwaves.
• Successfully produced a Bell state with a fidelity of 99.7(1)%, accounting for errors.
• Demonstrated qubit stabilization against fluctuating energy shifts without nulling the microwave field.

Conclusions:

• The developed gate is a significant advancement for room-temperature quantum computing.
• Dynamical decoupling effectively enhances qubit coherence and gate fidelity.
• This method provides a robust pathway for building scalable ion trap quantum processors.