Hannover 2020 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 24: Quantum Information (Quantum Computing)
Q 24.3: Talk
Wednesday, March 11, 2020, 11:45–12:00, e001
Benchmarking high-fidelity mixed-species entangling gates — •Vera Schäfer, Amy Hughes, Keshav Thirumalai, David Nadlinger, Christopher Ballance, and David Lucas — Department of Physics, University of Oxford, UK
Simultaneous trapping of two different elements of ion allows the manipulation of one without corruption of the electronic state of the other. An entangling gate between two species offers the freedom to select ions with different strengths for different tasks, and to transfer information from one to the other depending on the task at hand. Such a gate is an essential element in quantum logic spectroscopy, quantum networking and quantum information processing.
43Ca+ and 88Sr+ are two species well-suited for different aspects of quantum computing, and have transition frequencies only 20 THz apart. Therefore a two-qubit σz ⊗ σz gate may be driven on both species simultaneously using a single pair of Raman beams. I will present such a gate with fidelity 99.8(2)%, pushing mixed-species gate fidelities close to the best single-species entangling gates (99.9%). We use different methods to perform a full characterisation of this gate: with two-qubit randomised benchmarking we measure a fidelity of 99.72(6)% with sequences involving up to 75 entangling gates, or 30 interleaved entangling gates. From gate-set tomography we deduce a fidelity of 99.4(4)% for the two-qubit operations.
I will further present progress towards a mixed-species Mølmer-Sørensen gate on the same crystal, comparing the two methods.