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arXiv · 2105.05828

High-Fidelity Bell-State Preparation with $^{40}$Ca$^+$ Optical Qubits

Craig R. Clark·Holly N. Tinkey·Brian C. Sawyer·Adam M. Meier·Karl A. Burkhardt·Christopher M. Seck·Christopher M. Shappert·Nicholas D. Guise·Curtis E. Volin·Spencer D. Fallek·Harley T. Hayden·Wade G. Rellergert·Kenton R. Brown
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Abstract

Entanglement generation in trapped-ion systems has relied thus far on two distinct but related geometric phase gate techniques: Molmer-Sorensen and light-shift gates. We recently proposed a variant of the light-shift scheme where the qubit levels are separated by an optical frequency [B. C. Sawyer and K. R. Brown, Phys. Rev. A 103, 022427 (2021)]. Here we report an experimental demonstration of this entangling gate using a pair of $^{40}$Ca$^+$ ions in a cryogenic surface-electrode ion trap and a commercial, high-power, 532 nm Nd:YAG laser. Generating a Bell state in 35 $\mu$s, we directly measure an infidelity of $6(3) \times 10^{-4}$ without subtraction of experimental errors. The 532 nm gate laser wavelength suppresses intrinsic photon scattering error to $\sim 1 \times 10^{-5}$.

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Craig R. Clark, Holly N. Tinkey, Brian C. Sawyer, Adam M. Meier, Karl A. Burkhardt, Christopher M. Seck, Christopher M. Shappert, Nicholas D. Guise, Curtis E. Volin, Spencer D. Fallek, Harley T. Hayden, Wade G. Rellergert, Kenton R. Brown. 2021-05-12. High-Fidelity Bell-State Preparation with $^{40}$Ca$^+$ Optical Qubits. https://doi.org/10.1103/physrevlett.127.130505

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