High-Fidelity Preparation, Gates, Memory, and Readout of a Trapped-Ion Quantum Bit.
Physical review letters 113:22 (2014) 220501
Abstract:
We implement all single-qubit operations with fidelities significantly above the minimum threshold required for fault-tolerant quantum computing, using a trapped-ion qubit stored in hyperfine "atomic clock" states of ^{43}Ca^{+}. We measure a combined qubit state preparation and single-shot readout fidelity of 99.93%, a memory coherence time of T_{2}^{*}=50 sec, and an average single-qubit gate fidelity of 99.9999%. These results are achieved in a room-temperature microfabricated surface trap, without the use of magnetic field shielding or dynamic decoupling techniques to overcome technical noise.Microwave control electrodes for scalable, parallel, single-qubit operations in a surface-electrode ion trap
Applied Physics B Springer Nature 114:1-2 (2014) 3-10
Injection locking of two frequency-doubled lasers with 3.2 GHz offset for driving Raman transitions with low photon scattering in 43Ca+
Optics Letters 38:23 (2013) 5087-5089
Abstract:
We describe the injection locking of two infrared (794 nm) laser diodes that are each part of a frequency-doubled laser system. An acousto-optic modulator in the injection path gives an offset of 1.6 GHz between the lasers for driving Raman transitions between states in the hyperfine split (by 3.2 GHz) ground level of 43Ca+. The offset can be disabled for use in 40Ca+. We measure the relative linewidth of the frequency-doubled beams to be 42 mHz in an optical heterodyne measurement. The use of both injection locking and frequency doubling combines spectral purity with high optical power. Our scheme is applicable for providing Raman beams across other ion species and neutral atoms where coherent optical manipulation is required. © 2013 Optical Society of America.A microfabricated ion trap with integrated microwave circuitry
ArXiv 1210.3272 (2012)
Abstract:
We describe the design, fabrication and testing of a surface-electrode ion trap, which incorporates microwave waveguides, resonators and coupling elements for the manipulation of trapped ion qubits using near-field microwaves. The trap is optimised to give a large microwave field gradient to allow state-dependent manipulation of the ions' motional degrees of freedom, the key to multiqubit entanglement. The microwave field near the centre of the trap is characterised by driving hyperfine transitions in a single laser-cooled 43Ca+ ion.Background-free detection of trapped ions
Applied Physics B: Lasers and Optics 107:4 (2012) 1175-1180