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A: Fachverband Atomphysik
A 43: Ultra-cold Atoms, Ions and BEC VI (joint session A/Q)
A 43.1: Talk
Friday, March 6, 2026, 14:30–14:45, N 1
High fidelity quantum logic on two trapped-ion qubits without ground-state cooling — Amy Hughes, Raghavendra Srinivas, Clemens Löschnauer, •Hannah Knaack, Roland Matt, Chris Ballance, Maciej Malinowski, Thomas Harty, Tyler Sutherland, and Oxford Ionics team — Oxford Ionics, Oxford, United Kingdom
We introduce the *smooth gate* - a novel entangling gate method for trapped-ion qubits where residual motional errors are adiabatically eliminated by ramping the gate detuning. We combine the power of this technique with the robustness of electronic qubit control [1] to perform two-qubit gates with an estimated error of < 1 × 10−4 without the use of ground-state cooling. We characterise the gate error using a new protocol (inspired by subspace randomised benchmarking [2]) which does not require the use of any single-qubit rotations. We further show that the error remains < 5 × 10−4 for Doppler-cooled ions with gate mode temperatures of up to n = 9.4(3). These results show that trapped-ion quantum computers can be operated above the Doppler limit, allowing for significantly faster device operation.
[1] C. M. Löschnauer et al., PRX Quantum 6, 040313 (2025)
[2] C. H. Baldwin et al., Phys. Rev. Research 2, 013317 (2020)
Keywords: trapped ions; quantum computing; two-qubit gate; gate fidelity