Theory of robust multi-qubit non-adiabatic gates for trapped-ions

TL;DR

This paper introduces a theoretical framework for multi-qubit non-adiabatic gates in trapped-ion systems, enabling faster, high-fidelity entangling operations that reduce gate count and are suitable for quantum simulation.

Contribution

It presents a novel method for multi-qubit entangling gates that operate outside the adiabatic regime using all normal modes of motion, improving efficiency and fidelity.

Findings

Enables multi-qubit entangling gates with high fidelity

Operates at rates comparable to ion-trap frequencies

Supports Hamiltonian engineering for quantum simulation

Abstract

The prevalent approach to executing quantum algorithms on quantum computers is to break-down the algorithms to a concatenation of universal gates, typically single and two-qubit gates. However such a decomposition results in long gate sequences which are exponential in the qubit register size. Furthermore, gate fidelities tend to decrease when acting in larger qubit registers. Thus high-fidelity implementations in large qubit registers is still a prominent challenge. Here we propose and investigate multi-qubit entangling gates for trapped-ions. Our gates couple many qubits at once, allowing to decrease the total number of gates used while retaining a high gate fidelity. Our method employs all of the normal-modes of motion of the ion chain, which allows to operate outside of the adiabatic regime and at rates comparable to the secular ion-trapping frequency. Furthermore we extend our method for generating Hamiltonians which are suitable for quantum analog simulations, such as a nearest-neighbour spin Hamiltonian or the Su-Schrieffer-Heeger Hamiltonian.