Research On The Model Of Surface Electrode Ion Trap And The Microfabrication

The quantum system established based on quantum mechanics is a scheme which has the potential to surpass the classical computer. Surface electrodes ion trap is one of these techniques. As the better scalability, the longer decoherence time, fidelity to initialize and measure, surface electrode ion trap quantum computing systems has been considered as one of the most promising solutions.Firstly, this paper introduces the principle of surface electrode ion trap. In the surface electrode ion trap quantum computing systems, ion’s two levels is used as two states of qubit. By laser field coupling with ion qubits and collective oscillated qubits, it can implement the operation between two different qubits, which is called quantum logic. The RF electrodes and the DC electrodes of the surface electrode ion trap generated potential trap, where ion was trapped. Trap depth and ion heating rate are the important indicator to evaluate the performance of surface electrode ion trap.Considered with the effect of power loss and voltage loss of substrate, this paper modifies the model of trap depth and ion heating rate. Drawing on the idea of "quasi-TEM" model used in study of microwave circuits, this paper proposes the equivalent circuit model of surface electrode ion trap, and then obtains the analytical expression of power loss and voltage loss. For ion heating rate, this paper considers the impact of the electrode temperature change caused by substrate power loss, and then corrects the analytical model of ion heating rate, so as to make the forecast results more accurate. The analytical model of trap depth proposed in this paper consider the effect of the mass and charge of trapped ions, the amplitude of rf-voltage, voltage loss of substrate, the absolute size and relative size of ion trap. What’s more, this paper discovery the variation law when down size of electrodes with constant electric field, and explanation the difference of trap depth between surface electrode ion trap with different substrate materials. As this paper re-proposes the analytic expression, the voltage loss of Si substrate can reduce the trap depth by 17.19%, and the power loss would accelerate the ion heating rate by 13.37%.This paper proposed an optimization design for surface electrode ion trap, which optimizes the size of electrodes and the structure of substrate. For electrodes design, this paper considers the trap depth, the substrate voltage loss, ions heating rate and the efficiency of the control voltage. For substrate design, in order to reduce the power loss and voltage loss, this paper proposes the vacuum trench insulation structure, etching an isolation trench between RF electrode and DC electrode on surface of the substrate, so as to reduce the conductivity and capacitance. The simulation results illuminate that, compared with the normal ion trap, the optimization electrode design can increase 3.8% trap depth, and enhance the efficiency of control voltage by 20.22%. On the other hand, the ion trap with vacuum trench insulation exhibits a 20.22% increase in trap depth and a 54.44% reduction in power loss.At last, this paper design and implement the manufacturing process of the surface electrodes ion trap. In order to reduce the effect of ion heating rate caused by electrode’s Johnson noise, equivalent resistance of surface electrode ion trap electrode should be reduce as much as possible. So, a thick electrode is wanted. In addition, in order to reduce the effect of ion trap ion heating rates by fluctuated patch potential, better flatness of electrode surface is required. Thus, metal deposition to form a thick and flat surface electrode is an important step in manufacturing process. The process manufacturing steps include: wafer cleaning, thermal evaporation, lithography, electroplating, stripping, etching and bonding. In order to reach the manufacture requirements about surface ion trap, this paper selects the manufacture parameters of each step by thorough experiment.This paper studies the working principle for quantum computing surface electrodes ion trap, amended the relevant theoretical models proposed to optimize the surface of the electrodes of the ion trap design, and the design for its manufacturing process, exploring the parameters of each process step. In further work, we need to further improve the model of the surface electrodes ion trap research, expand the modeling of movement control scalable multi-well region of the surface electrodes ion trap, complete the surface electrode ion trap chip production process, and finally, combining physical experimental platform, expand scientific research experiments with surface electrodes ion trap.