Two-qubit gate protocols with microwave-dressed Rydberg ions in a linear Paul trap

New Journal of Physics, vol. 27, pp. 064502

Abstract

Abstract Ultracold trapped atomic ions excited into highly energetic Rydberg states constitute a promising platform for scalable quantum information processing. Elementary building blocks for such tasks are high-fidelity and sufficiently fast entangling two-qubit gates, which can be achieved via strong dipole–dipole interactions between microwave-dressed Rydberg ions, as recently demonstrated experimentally (Zhang et al 2020 Nature 580 345). We theoretically investigate the performance of three protocols leading to controlled-phase gate operations. Starting from a microscopic description of Rydberg ions in a linear Paul trap, we derive an effective Hamiltonian that faithfully captures the essential dynamics underlying the gate protocols. We then use an optimization scheme to fine-tune experimentally controllable parameters like laser detuning and Rabi frequency to yield maximal gate fidelity under each studied protocol. We show how non-adiabatic transitions resulting from fast laser driving relative to the characteristic time scales of the system detrimentally affect the fidelity. Despite this, we demonstrate that in the realistic scenario of Rydberg ions with finite radiative lifetimes, optimizing the best found gate protocol enables achievement of fidelities as high as 99.25 % for a gate time of 0.2 μ s . This considerably undercuts entangling gate durations between ground state ions, for which gate times are typically limited by the comparably slower time scales of vibrational modes. Overall, this places trapped Rydberg ions into the regime where fast high-accuracy quantum computing and eventually quantum error correction become possible.

Authors 5

1. Joseph W. P. Wilkinson

   University of Tübingen

   Affiliation as printed

   Institut für Theoretische Physik and Center for Integrated Quantum Science and Technology, Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen, Germany

2. Katrin Bolsmann Aachen Institut für Quanteninformation

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Institut für Quanteninformation, RWTH Aachen University, Otto-Blumenthal-Straße 20, 52074 Aachen, Germany

   Institut für Theoretische Nanoelektronik, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany

3. Thiago L. M. Guedes Aachen Institut für Quanteninformation

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Institut für Quanteninformation, RWTH Aachen University, Otto-Blumenthal-Straße 20, 52074 Aachen, Germany

   Institut für Theoretische Nanoelektronik, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany

4. Markus Michael Müller Aachen Institut für Quanteninformation

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Institut für Quanteninformation, RWTH Aachen University, Otto-Blumenthal-Straße 20, 52074 Aachen, Germany

   Institut für Theoretische Nanoelektronik, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany

5. Igor Lesanovsky

   University of Nottingham · University of Tübingen

   Affiliation as printed

   Institut für Theoretische Physik and Center for Integrated Quantum Science and Technology, Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen, Germany

   School of Physics and Astronomy and Centre for the Mathematics and Theoretical Physics of Quantum Non-Equilibrium Systems, The University of Nottingham, Nottingham NG7 2RD, United Kingdom