Jan 19 – 30, 2015
Ecole de Physique des Houches
Europe/Zurich timezone

Near-field microwave operations with 43Ca+ qubits

Not scheduled
Ecole de Physique des Houches

Ecole de Physique des Houches



Mr James Tarlton (University of Oxford)


Our recent work on performing near-field microwave qubit operations using $^{43}$Ca$^{+}$ ions will be reported. Using intermediate-field “atomic clock” states, we have demonstrated single-qubit preparation, gates and readout each with 99.9% fidelity or better, with operation times much less than the qubit coherence time of $T_{2}^{*} = 50$s [1]. These results were achieved in a room-temperature surface trap incorporating integrated microwave waveguides and resonators, using near-field microwaves to drive the qubit gates [2]. We have also used the same trap to implement two-qubit gates with approximately 90% fidelity, the best ever achieved using microwaves [3]. In a separate experiment, we have designed and fabricated a surface trap to implement scalable independent qubit addressing using near-field microwaves [4]. We drive qubit rotations with microwaves in one trap zone while nulling the microwave field in a neighbouring zone (1mm distant), achieving spin-flip addressing errors of order 10$^{-6}$. We have also been working on improving the stability of our 146G magnetic field. This is the most significant source of error in our state preparation and readout in the intermediate-field scheme, and it also limits the quality with which diagnostics and characterisations can be carried out. We expect to be able to achieve a stability of below 1mG rms. Our progress will be reported. References: [1] T. P. Harty et al., Phys. Rev. Lett. **113**, 220501 (2014). [2] Brown et al., Phys. Rev. A **84**, 030303(R) (2011) and D. T. C. Allcock et al., Appl. Phys. Lett. **102**, 044103 (2013). [3] C. Ospelkaus et al., Nature **476**, 181 (2011). [4] D. P. L. Aude Craik et al., Appl. Phys. B **114**, 3 (2014).

Primary authors

Prof. Andrew Steane (University of Oxford) Mr Chris Ballance (University of Oxford) Dr David Lucas (University of Oxford) Prof. Derek Stacey (University of Oxford) Ms Diana Aude Craik (University of Oxford) Mr Hugo Janacek (University of Oxford) Mr James Tarlton (University of Oxford) Mr Keshav Thirumalai (University of Oxford) Mr Martin Sepiol (University of Oxford) Dr Norbert Linke (University of Oxford) Ms Sarah Woodrow (University of Oxford) Dr Thomas Harty (University of Oxford) Ms Vera Schäfer (University of Oxford)

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