Experimental demonstration of high fidelity ${}^{133}$ Ba $^+$ hyperfine qubitsExperimental demonstration of high fidelity ${}^{133}$Ba$^+$ hyperfine qubits

David Hucul, Justin Christensen, Eric R. Hudson +1 more

Bulletin of the American Physical SocietyMay 29, 20180 citations

Barium Qubit State Detection and Ba Ion-Photon Entanglement

Ksenia Sosnova, I. V. Inlek, Clayton Crocker +2 more

Bulletin of the American Physical SocietyMay 25, 20160 citations

Eliminating Leakage Errors in Hyperfine Qubits

Daniel T. Stack, David Hayes, Bryce Bjork +3 more

Bulletin of the American Physical SocietyJun 2, 20200 citations

High-fidelity operation of a radioactive trapped-ion qubit, $^{133}$ Ba $^+$ High-fidelity operation of a radioactive trapped-ion qubit, $^{133}$Ba$^+$

Justin Christensen

$^{133}$ Ba $^+$ has been identified as an attractive ion for quantum information processing due to the unique combination of its spin-1/2 nucleus, visible wavelength electronic transitions, and long D-state lifetimes ($\\tau\\sim $1~min). Using a microgram source of radioactive material, we trap and laser-cool the synthetic \\textit{A} = 133 radioisotope of barium II ($ \\tau_{1/2} \\approx 10.5 $~yr) in a radio-frequency ion trap. To demonstrate high fidelity qubit operations, a number of unknown state energies were needed. We measure the isotope shift and hyperfine structure of the 6$ ^2 $P$ _{1/2}\\leftrightarrow 5^2 $D$ _{3/2}$ electronic transition needed for laser cooling, state preparation, and state detection of the clock-state hyperfine and optical qubits. For high-fidelity operations with electron shelving, we report measurements of the 6 $^2$ P $_{3/2}$ and $5^2$ D $_{5/2}$ hyperfine splittings, as well as the~6 $^2$ P $_{3/2}~\\leftrightarrow~6^2$ S $_{1/2}$ and ~6 $^2$ P $_{3/2}~\\leftrightarrow~5^2$ D $_{5/2}$ transition frequencies. Using these transitions, we demonstrate high-fidelity \\ba \\ hyperfine qubit manipulation with electron shelving detection to benchmark qubit state preparation and measurement (SPAM). Using single-shot, threshold discrimination, we measure an average SPAM fidelity of $\\mathcal{F} = 0.99971(3)$ , a factor of $\\approx$ 2 improvement over the best reported performance of any qubit.Finally, we report the 6 $^2$ P $_{1/2}\\leftrightarrow 5^2$ D $_{3/2}$ electronic transition isotope shift for the rare \\textit{A} = 130 and 132 barium nuclides, completing the spectroscopic characterization necessary for laser cooling all long-lived barium II isotopes.$^{133}$Ba$^+$ has been identified as an attractive ion for quantum information processing due to the unique combination of its spin-1/2 nucleus, visible wavelength electronic transitions, and long D-state lifetimes ($\\tau\\sim $1~min). Using a microgram source of radioactive material, we trap and laser-cool the synthetic \\textit{A} = 133 radioisotope of barium II ($\\tau_{1/2} \\approx 10.5$~yr) in a radio-frequency ion trap. To demonstrate high fidelity qubit operations, a number of unknown state energies were needed. We measure the isotope shift and hyperfine structure of the 6$^2$P$_{1/2}\\leftrightarrow 5^2$D$_{3/2}$ electronic transition needed for laser cooling, state preparation, and state detection of the clock-state hyperfine and optical qubits. For high-fidelity operations with electron shelving, we report measurements of the 6$^2$P$_{3/2}$ and $5^2$D$_{5/2}$ hyperfine splittings, as well as the~6$^2$P$_{3/2}~\\leftrightarrow~6^2$S$_{1/2}$ and ~6$^2$P$_{3/2}~\\leftrightarrow~5^2$D$_{5/2}$ transition frequencies. Using these transitions, we demonstrate high-fidelity \\ba \\ hyperfine qubit manipulation with electron shelving detection to benchmark qubit state preparation and measurement (SPAM). Using single-shot, threshold discrimination, we measure an average SPAM fidelity of $\\mathcal{F} = 0.99971(3)$, a factor of $\\approx$ 2 improvement over the best reported performance of any qubit.Finally, we report the 6$^2$P$_{1/2}\\leftrightarrow 5^2$D$_{3/2}$ electronic transition isotope shift for the rare \\textit{A} = 130 and 132 barium nuclides, completing the spectroscopic characterization necessary for laser cooling all long-lived barium II isotopes.

Jan 1, 20203 citations

Ultra-High Fidelity Operation of the $^{133}$ Ba $^+$ qubitUltra-High Fidelity Operation of the $^{133}$Ba$^+$ qubit

Justin Christensen, David Hucul, Eric R. Hudson +1 more

Bulletin of the American Physical SocietyMay 29, 20190 citations

Polarization-insensitive state preparation for trapped-ion hyperfine qubits

A. D. Leu, Matthew C. Smith, Mario F. Gely +1 more

Quantum state preparation for trapped-ion qubits often relies on high-quality circularly polarized light, which may be difficult to achieve with chip-based integrated optics technology. We propose and implement a hybrid optical and microwave scheme for intermediate-field hyperfine qubits which instead relies on frequency selectivity. Experimentally, we achieve 99.94 % fidelity for linearly polarized ( σ + / σ − ) light, using Ca + 43 at 28.8 mT. We find that the fidelity remains above 99.8 % for a mixture of all polarizations ( σ + / σ − / π ) . We calculate that the method is capable of 99.99 % fidelity in Ca + 43 , and even higher fidelities in heavier ions such as Ba + 137 . Published by the American Physical Society 2024Quantum state preparation for trapped-ion qubits often relies on high-quality circularly polarized light, which may be difficult to achieve with chip-based integrated optics technology. We propose and implement a hybrid optical and microwave scheme for intermediate-field hyperfine qubits which instead relies on frequency selectivity. Experimentally, we achieve 99.94 % fidelity for linearly polarized ( σ + / σ − ) light, using Ca + 43 at 28.8 mT. We find that the fidelity remains above 99.8 % for a mixture of all polarizations ( σ + / σ − / π ) . We calculate that the method is capable of 99.99 % fidelity in Ca + 43 , and even higher fidelities in heavier ions such as Ba + 137 . Published by the American Physical Society 2024

arXiv:2406.14448Physical Review AOct 16, 20242 citations

Preparation and detection of a

^{137}

^{+}

hyperfine qubit

Experimental demonstration of high fidelity

{}^{133}

^+

hyperfine qubits

High-fidelity operation of a radioactive trapped-ion qubit,

^{133}

^+

^{133}

^+

has been identified as an attractive ion for quantum information processing due to the unique combination of its spin-1/2 nucleus, visible wavelength electronic transitions, and long D-state lifetimes ($\\tau\\sim

1~min). Using a microgram source of radioactive material, we trap and laser-cool the synthetic \\textit{A} = 133 radioisotope of barium II (

\\tau_{1/2} \\approx 10.5

~yr) in a radio-frequency ion trap. To demonstrate high fidelity qubit operations, a number of unknown state energies were needed. We measure the isotope shift and hyperfine structure of the 6

P

_{1/2}\\leftrightarrow 5^2

D

_{3/2}$ electronic transition needed for laser cooling, state preparation, and state detection of the clock-state hyperfine and optical qubits. For high-fidelity operations with electron shelving, we report measurements of the 6

^2

_{3/2}

and

5^2

_{5/2}

hyperfine splittings, as well as the~6

^2

_{3/2}~\\leftrightarrow~6^2

_{1/2}

and ~6

^2

_{3/2}~\\leftrightarrow~5^2

_{5/2}

transition frequencies. Using these transitions, we demonstrate high-fidelity \\ba \\ hyperfine qubit manipulation with electron shelving detection to benchmark qubit state preparation and measurement (SPAM). Using single-shot, threshold discrimination, we measure an average SPAM fidelity of

\\mathcal{F} = 0.99971(3)

, a factor of

\\approx

2 improvement over the best reported performance of any qubit.Finally, we report the 6

^2

_{1/2}\\leftrightarrow 5^2

_{3/2}

electronic transition isotope shift for the rare \\textit{A} = 130 and 132 barium nuclides, completing the spectroscopic characterization necessary for laser cooling all long-lived barium II isotopes.

Ultra-High Fidelity Operation of the

^{133}

^+

qubit