Demonstration of sympathetic cooling and diabatic ion transport in an ion trap quantum computer

Ion transport on microchip X-junction ion trap array is a key ingredient to for the implementation of quantum algorithms on a trapped ion quantum computer (Fig. 1(a)). At Sussex we have recently realized a new generation of ion chips which incorporate an X-junction ion trap array as well as integrated current carrying wires required to implement high-fidelity 2-qubit gates (Fig. 1(b), Fig. 1(c)). We have already demonstrated transport through an X-junction ion trap array, along with other relevant shuttling operations. In order to execute quantum algorithm, we need to demonstrate fast ion transport operations making use of the idea of diabatic shuttling. We are developing diabatic shuttling as part of a collaboration with Florian Mintert's group at Imperial College London. In contrast to adiabatic ion transport where the ion remains of the bottom of the well of the shuttling potential, diabatic ion transport makes use of phase sensitive control of the trapping potentials in order to allow for fast transport without injecting kinetic energy to the ion. Sympathetic cooling is a key feature of an ion trap quantum computer as it allows to cool the ion holding quantum information without scrambling its internal state that is used to hold quantum information. Connecting sympathetic cooling and fast diabatic ion transport is a key ingredient in building a practical quantum computer. As part of this studentship, the student will demonstrate sympathetic cooling with Barium ions. The student will then introduce a set of ion transport protocols where they will demonstrate diabatic shuttling followed by sympathetic cooling. We will investigate optimal protocols and evaluate whether it is best to separate the quantum ion and the cooling ion before diabatic transport or carry out mixed species diabatic ion transport. The project will culminate in the execution of a quantum algorithm including gate execution, diabatic shuttling and sympathetic cooling.