Precision measurement of the 43Ca+ nuclear magnetic moment
Physical Review A American Physical Society 104:5 (2021) 052804
Abstract:
We report precision measurements of the nuclear magnetic moment of 43Ca+, made by microwave spectroscopy of the 4s2S1/2∣∣F=4,M=0⟩→∣∣F=3,M=1⟩ ground level hyperfine clock transition at a magnetic field of ≈146G, using a single laser-cooled ion in a Paul trap. We measure a clock-transition frequency of f=3199941076.920(46)Hz from which we determine μI/μN=−1.315350(9)(1) where the uncertainty (9) arises from uncertainty in the hyperfine A constant, and the (1) arises from the uncertainty in our measurement. This measurement is not corrected for diamagnetic shielding due to the bound electrons. We make a second measurement which is less precise but agrees with the first. We use our μI value in combination with previous NMR results to extract the change in shielding constant of calcium ions due to solvation in D2O:Δσ=−0.00022(1).An optically heated atomic source for compact ion trap vacuum systems
Review of Scientific Instruments AIP Publishing 92:3 (2021) 033205
Abstract:
We present a design for an atomic oven suitable for loading ion traps, which is operated via optical heating with a continuous-wave multimode diode laser. The absence of the low-resistance electrical connections necessary for Joule heating allows the oven to be extremely well thermally isolated from the rest of the vacuum system. Extrapolating from high-flux measurements of an oven filled with calcium, we calculate that a target region number density of 100 cm−3, suitable for rapid ion loading, will be produced with 175(10) mW of heating laser power, limited by radiative losses. With simple feedforward to the laser power, the turn-on time for the oven is 15 s. Our measurements indicate that an oven volume 1000 times smaller could still hold enough source metal for decades of continuous operation.Benchmarking a high-fidelity mixed-species entangling gate
Physical Review Letters American Physical Society 125:8 (2020) 080504
Abstract:
We implement a two-qubit logic gate between a 43Ca+ hyperfine qubit and a 88Sr+ Zeeman qubit. For this pair of ion species, the S–P optical transitions are close enough that a single laser of wavelength 402 nm can be used to drive the gate but sufficiently well separated to give good spectral isolation and low photon scattering errors. We characterize the gate by full randomized benchmarking, gate set tomography, and Bell state analysis. The latter method gives a fidelity of 99.8(1)%, comparable to that of the best same-species gates and consistent with known sources of error.High-rate high-fidelity entanglement of qubits across an elementary quantum network
Physical Review Letters American Physical Society 124:11 (2020) 110501
Abstract:
We demonstrate remote entanglement of trapped-ion qubits via a quantum-optical fiber link with fidelity and rate approaching those of local operations. Two 88Sr+ qubits are entangled via the polarization degree of freedom of two spontaneously emitted 422 nm photons which are coupled by high-numerical-aperture lenses into single-mode optical fibers and interfere on a beam splitter. A novel geometry allows high-efficiency photon collection while maintaining unit fidelity for ion-photon entanglement. We generate heralded Bell pairs with fidelity 94% at an average rate 182 s−1 (success probability 2.18×10−4).
Probing Qubit Memory Errors at the Part-per-Million Level.
Physical review letters 123:11 (2019) 110503-110503