Coherent Control of the Fine-Structure Qubit in a Single Alkaline-Earth Atom

Area of Science:

• Quantum Computing
• Atomic Physics
• Quantum Information Science

Background:

• Neutral atom qubits are a promising platform for quantum computing.
• Previous qubit encodings have limitations in speed and coherence.

Purpose of the Study:

• To demonstrate a novel neutral atom qubit using spin-orbit coupled metastable states in strontium-88.
• To explore rapid qubit control and measure coherence times for this new encoding.

Main Methods:

• Trapping a single strontium-88 atom in an optical tweezer.
• Encoding a qubit in the ^{3}P_{0} and ^{3}P_{2} metastable states.
• Utilizing Raman coupling and phase-locked clock lasers for qubit manipulation.
• Performing Rabi oscillations and Ramsey spectroscopy to characterize qubit performance.
• Tuning to magic trapping conditions using magnetic fields to optimize coherence.

Main Results:

• Successful preparation, readout, and coherent control of the novel qubit.
• Demonstration of Rabi oscillations across a >17 THz energy gap.
• Measurement of a transverse qubit coherence time (T_{2}) of 1.2 milliseconds under magic trapping conditions.
• Identification of noise sources limiting coherence time through quantum mechanical modeling.

Conclusions:

• This work presents the first realization of a neutral atom qubit based on spin-orbit coupled metastable states.
• The demonstrated rapid control and promising coherence times open a new avenue for neutral atom quantum computing.
• Future improvements are projected based on identified noise sources and system optimizations.