Robust Two-Qubit Gates Using Pulsed Dynamical Decoupling

• URL: http://arxiv.org/abs/2208.00187v2
• Date: Mon, 7 Nov 2022 10:07:52 GMT
• Title: Robust Two-Qubit Gates Using Pulsed Dynamical Decoupling
• Authors: Patrick Barthel, Patrick H. Huber, Jorge Casanova, I\~nigo Arrazola, Dorna Niroomand, Theeraphot Sriarunothai, Martin B. Plenio, Christof Wunderlich
• Abstract summary: We present the experimental implementation of a two-qubit phase gate, using a radio frequency (RF) controlled trapped-ion quantum processor. It allows for a tunable phase shift with high-fidelity results, in particular a fringe contrast up to $99_-2+1%$ is observed in Ramsey-type measurements. It holds the potential for fast gate speeds (gate times on the order of $100mu$s) by using two axial motional modes of a two-ion crystal.
• Score: 1.0539847330971805
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We present the experimental implementation of a two-qubit phase gate, using a radio frequency (RF) controlled trapped-ion quantum processor. The RF-driven gate is generated by a pulsed dynamical decoupling sequence applied to the ions' carrier transitions only. It allows for a tunable phase shift with high-fidelity results, in particular a fringe contrast up to $99_{-2}^{+1}\%$ is observed in Ramsey-type measurements. We also prepare a Bell state using this laser-free gate. The phase gate is robust against common sources of error. We investigate the effect of the excitation of the center-of-mass (COM) mode, errors in the axial trap frequency, pulse area errors and errors in sequence timing. The contrast of the phase gate is not significantly reduced up to a COM mode excitation $<20$ phonons, trap frequency errors of +10%, and pulse area errors of -8%. The phase shift is not significantly affected up to $<10$ phonons and pulse area errors of -2%. Both, contrast and phase shift are robust to timing errors up to -30% and +15%. The gate implementation is resource efficient, since only a single driving field is required per ion. Furthermore, it holds the potential for fast gate speeds (gate times on the order of $100~\mu$s) by using two axial motional modes of a two-ion crystal through improved setups.

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