Quantum 2025 – scientific programme

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MON: Monday Contributed Sessions

MON 6: QIP Implementations: Trapped Ions

MON 6.4: Talk

Monday, September 8, 2025, 15:00–15:15, ZHG007

Generating arbitrary coupling matrices for multi-qubit quantum gates — •Patrick H. Huber, Dorna Niroomand, Markus Nünnerich, Patrick Barthel, and Christof Wunderlich — Department of Physics, School of Science and Technology, University of Siegen, 57068 Siegen, Germany

An always-on, all-to-all Ising-type interaction between qubits in a quantum register can be provided by the Magnetic Gradient Induced Coupling (MAGIC) approach to quantum computing with trapped ions [1,2]. In that case, the interaction strength between radio frequency(rf)-controlled qubits is determined by the trapping potential and the applied magnetic field gradient.

Here we present a novel method that allows for the tuning of the qubits’ interaction without changing the trapping potential nor the magnetic field while simultaneously preserving the qubits’ coherence. This method uses pulsed dynamical decoupling and is demonstrated experimentally in a quantum register of four qubits encoded into hyperfine states of the electronic ground state of laser-cooled ¹⁷¹Yb⁺ ions . We synthesize an arbitrary coupling matrix within this quantum register and, furthermore, generate non-interacting subregisters. Thus, this method opens up a new path for efficiently synthesizing quantum algorithms when using an all-to-all Ising-type interaction between qubits.

[1] A. Khromova et al., Phys. Rev. Lett. 108, 220502 (2012). [2] P. Baßler et al., Quantum 7, 984 (2023).

Keywords: Multi-qubit gates; All-toAll-coupling; Ising interaction