A5091932323- Quantum Information and Cryptography
- Quantum Computing Algorithms and Architecture
- Quantum and electron transport phenomena
- Quantum optics and atomic interactions
- Advanced Frequency and Time Standards
- Neural Networks and Reservoir Computing
- Astro and Planetary Science
- Atomic and Subatomic Physics Research
University of Oxford
2023-2024
We use electronic microwave control methods to implement addressed single-qubit gates with high speed and fidelity, for $^{43}{\mathrm{Ca}}^{+}$ hyperfine ``atomic clock'' qubits in a cryogenic (100 K) surface trap. For single qubit, we benchmark an error of $1.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ per Clifford gate (implemented using 600 ns $\ensuremath{\pi}/2$ pulses). 2 the same trap zone (ion separation $5\text{ }\text{ }\mathrm{\ensuremath{\mu}}\mathrm{m}$), spatial...
Microwave-driven logic is a promising alternative to laser control in scaling trapped-ion based quantum processors. We implement Mølmer-Sørensen two-qubit gates on <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msup><a:mrow/><a:mn>43</a:mn></a:msup><a:msup><a:mrow><a:mi>Ca</a:mi></a:mrow><a:mo>+</a:mo></a:msup></a:math> hyperfine clock qubits cryogenic <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mo>(</b:mo><b:mo>≈</b:mo><b:mn>25</b:mn><b:mo> </b:mo><b:mi...
Reducing errors in quantum gates is critical to the development of computers. To do so, any distortions control signals should be identified; however, conventional tools are not always applicable when part system under high vacuum, cryogenic, or microscopic. Here, we demonstrate a method detect and compensate for amplitude-dependent phase changes, using qubit itself as probe. The technique implemented microwave-driven trapped-ion qubit, where correcting leads threefold improvement error...
We use electronic microwave control methods to implement addressed single-qubit gates with high speed and fidelity, for ^{43}Ca^{+} hyperfine "atomic clock" qubits in a cryogenic (100 K) surface trap. For single qubit, we benchmark an error of 1.5×10^{-6} per Clifford gate (implemented using 600 ns π/2 pulses). 2 the same trap zone (ion separation 5 μm), spatial field gradient, combined efficient four-pulse scheme, independent gates. Parallel randomized benchmarking on both yields average...
Reducing errors in quantum gates is critical to the development of computers. To do so, any distortions control signals should be identified, however, conventional tools are not always applicable when part system under high vacuum, cryogenic, or microscopic. Here, we demonstrate a method detect and compensate for amplitude-dependent phase changes, using qubit itself as probe. The technique implemented microwave-driven trapped ion qubit, where correcting leads three-fold improvement...
Microwave-driven logic is a promising alternative to laser control in scaling trapped-ion based quantum processors. However, such electronic gates have yet match the speed offered by their laser-driven counterparts. Here, we implement M{\o}lmer-S{\o}rensen two-qubit on $^{43}\text{Ca}^+$ hyperfine clock qubits cryogenic ($\approx25~\text{K}$) surface trap, driven near-field microwaves. We achieve gate durations of $154~\mu\text{s}$ (with $1.0(2)\%$ error) and $331~\mu\text{s}$ ($0.5(1)\%$...
Quantum state preparation for trapped-ion qubits often relies on high-quality circularly-polarised light, which may be difficult to achieve with chip-based integrated optics technology. We propose and implement a hybrid optical/microwave scheme intermediate-field hyperfine instead frequency selectivity. Experimentally, we $99.94\%$ fidelity linearly-polarised ($\sigma^+$/$\sigma^-$) using $^{43}$Ca$^+$ at 28.8 mT. find that the remains above $99.8\%$ mixture of all polarisations...
A leading approach to implementing small-scale quantum computers has been use laser beams, focused micron spot sizes, address and entangle trapped ions in a linear crystal. Here we propose method implement individually addressed entangling gate interactions, but driven by microwave fields, with spatial resolution of few microns, corresponding <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"...
Quantum state preparation for trapped-ion qubits often relies on high-quality circularly polarized light, which may be difficult to achieve with chip-based integrated optics technology. We propose and implement a hybrid optical microwave scheme intermediate-field hyperfine instead frequency selectivity. Experimentally, we <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mn>99.94</a:mn><a:mo>%</a:mo></a:mrow></a:math> fidelity linearly <b:math...
Trapped ions provide a highly controlled platform for quantum sensors, clocks, simulators, and computers, all of which depend on cooling close to their motional ground state. Existing methods like Doppler, resolved sideband, dark resonance balance trade-offs between the final temperature rate. A traveling polarization gradient has been shown cool multiple modes quickly in parallel, but utilizing stable can achieve lower ion energies, while also allowing more tailorable light-matter...
We report the achievement of single-qubit gates with sub-part-per-million error rates, in a trapped-ion $^{43}$Ca$^{+}$ hyperfine clock qubit. explore speed/fidelity trade-off for gate times $4.4\leq t_{g}\leq35~\mu$s, and benchmark minimum $1.5(4) \times 10^{-7}$. Gate calibration errors are suppressed to $< 10^{-8}$, leaving qubit decoherence ($T_{2}\approx 70$ s), leakage measurement as dominant contributions. The ion is held above microfabricated surface-electrode trap which incorporates...
In 1995, Cirac and Zoller proposed the first concrete implementation of a small-scale quantum computer, using laser beams focused to micron spot sizes address individual trapped ions in linear crystal. Here we propose method focus entangling gate interactions, but driven by microwave fields, micron-sized zones, corresponding $10^{-5}$ wavelengths. We demonstrate ability suppress spin-dependent force single ion, find required interaction introduces $3.7(4)\times 10^{-4}$ error per emulated...