Verifiable Blind Quantum Computing with Trapped Ions and Single Photons.
Physical review letters 132:15 (2024) 150604
Abstract:
We report the first hybrid matter-photon implementation of verifiable blind quantum computing. We use a trapped-ion quantum server and a client-side photonic detection system networked via a fiber-optic quantum link. The availability of memory qubits and deterministic entangling gates enables interactive protocols without postselection-key requirements for any scalable blind server, which previous realizations could not provide. We quantify the privacy at ≲0.03 leaked classical bits per qubit. This experiment demonstrates a path to fully verified quantum computing in the cloud.Breaking the entangling gate speed limit for trapped-ion qubits using a phase-stable standing wave
Physical Review Letters American Physical Society 131:22 (2023) 220601
Abstract:
All laser-driven entangling operations for trapped-ion qubits have hitherto been performed without control of the optical phase of the light field, which precludes independent tuning of the carrier and motional coupling. By placing 88Sr+ ions in a λ=674 nm standing wave, whose relative position is controlled to ≈λ/100, we suppress the carrier coupling by a factor of 18, while coherently enhancing the spin-motion coupling. We experimentally demonstrate that the off-resonant carrier coupling imposes a speed limit for conventional traveling-wave Mølmer-Sørensen gates; we use the standing wave to surpass this limit and achieve a gate duration of 15 μs, restricted by the available laser power.Cryogenic ion trap system for high-fidelity near-field microwave-driven quantum logic
Quantum Science and Technology IOP Publishing 9:1 (2023) 015007
Abstract:
We report the design, fabrication, and characterization of a cryogenic ion trap system for the implementation of quantum logic driven by near-field microwaves. The trap incorporates an on-chip microwave resonator with an electrode geometry designed to null the microwave field component that couples directly to the qubit, while giving a large field gradient for driving entangling logic gates. We map the microwave field using a single 43Ca+ ion, and measure the ion trapping lifetime and motional mode heating rates for one and two ions.Do quantum circuit Born machines generalize?
Quantum Science and Technology IOP Publishing 8:3 (2023)
Coherent Control of Trapped-Ion Qubits with Localized Electric Fields.
Physical review letters 131:2 (2023) 020601