Polarisation-insensitive state preparation for trapped-ion hyperfine qubits

Abstract

Quantum state preparation for trapped-ion qubits often relies on high-quality circularly-polarised light, which may be difficult to achieve with chip-based integrated optics technology. We propose and implement a hybrid optical/microwave scheme for intermediate-field hyperfine qubits which instead relies on frequency selectivity. Experimentally, we achieve $99.94\%$ fidelity for linearly-polarised (${\sigma }^{+}$/${\sigma }^{-}$) light, using ${}^{43}$Ca${}^{+}$ at 28.8 mT. We find that the fidelity remains above $99.8\%$ for a mixture of all polarisations (${\sigma }^{+}$/${\sigma }^{-}$/$\pi$). We calculate that the method is capable of $99.99\%$ fidelity in ${}^{43}$Ca${}^{+}$, and even higher fidelities in heavier ions such as ${}^{\text{137}}$Ba${}^{\text{+}}$.

References in corpus (21)

• Surface codes: Towards practical large-scale quantum computation
• High-fidelity quantum logic gates using trapped-ion hyperfine qubits
• High-fidelity two-qubit quantum logic gates using trapped calcium-43 ions
• High-fidelity preparation, gates, memory and readout of a trapped-ion quantum bit
• High-Fidelity Universal Gate Set for ${}^9$Be${}^{+}$ Ion Qubits
• High-fidelity readout of trapped-ion qubits
• Single ion-qubit exceeding one hour coherence time
• Integrated optical multi-ion quantum logic
• High-fidelity laser-free universal control of two trapped ion qubits
• Multi-Element Logic Gates for Trapped-Ion Qubits
• High-Fidelity Bell-State Preparation with ${}^{40}$Ca${}^{+}$ Optical Qubits
• High-fidelity trapped-ion quantum logic using near-field microwaves
• $\text{omg}$ Blueprint for trapped ion quantum computing with metastable states
• Precise and diffraction-limited waveguide-to-free-space focusing gratings
• High fidelity state preparation and measurement of ion hyperfine qubits with I > 1/2
• Fast, high-fidelity addressed single-qubit gates using efficient composite pulse sequences
• Probing Qubit Memory Errors at the Part-per-Million Level
• Scalable hyperfine qubit state detection via electron shelving in the ${}^2$D${}_{5/2}$ and ${}^2$F${}_{7/2}$ manifolds in ${}^{171}$Yb${}^{+}$
• Cryogenic ion trap system for high-fidelity near-field microwave-driven quantum logic
• Dark-resonance Doppler cooling and high fluorescence in trapped Ca-43 ions at intermediate magnetic field
• Pure circularly polarized light emission from waveguide microring resonators

Cited by in corpus (1)

• Single-qubit gates with errors at the $10^{-7}$ level