No Arabic abstract
One of the outstanding challenges for ion trap quantum information processing is to accurately detect the states of many ions in a scalable fashion. In the particular case of surface traps, geometric constraints make imaging perpendicular to the surface appealing for light collection at multiple locations with minimal cross-talk. In this report we describe an experiment integrating Diffractive Optic Elements (DOEs) with surface electrode traps, connected through in-vacuum multi-mode fibers. The square DOEs reported here were all designed with solid angle collection efficiencies of 3.58%; with all losses included a detection efficiency of 0.388% (1.02% excluding the PMT loss) was measured with a single Ca+ ion. The presence of the DOE had minimal effect on the stability of the ion, both in temporal variation of stray electric fields and in motional heating rates.
In this study, we report the first Cu-filled through silicon via (TSV) integrated ion trap. TSVs are placed directly underneath electrodes as vertical interconnections between ion trap and a glass interposer, facilitating the arbitrary geometry design with increasing electrodes numbers and evolving complexity. The integration of TSVs reduces the form factor of ion trap by more than 80%, minimizing parasitic capacitance from 32 to 3 pF. A low RF dissipation is achieved in spite of the absence of ground screening layer. The entire fabrication process is on 12-inch wafer and compatible with established CMOS back end process. We demonstrate the basic functionality of the trap by loading and laser-cooling single 88Sr+ ions. It is found that both heating rate (17 quanta/ms for an axial frequency of 300 kHz) and lifetime (~30 minutes) are comparable with traps of similar dimensions. This work pioneers the development of TSV-integrated ion traps, enriching the toolbox for scalable quantum computing.
We describe the design, fabrication and testing of a surface-electrode ion trap, which incorporates microwave waveguides, resonators and coupling elements for the manipulation of trapped ion qubits using near-field microwaves. The trap is optimised to give a large microwave field gradient to allow state-dependent manipulation of the ions motional degrees of freedom, the key to multiqubit entanglement. The microwave field near the centre of the trap is characterised by driving hyperfine transitions in a single laser-cooled 43Ca+ ion.
We describe an ex-situ surface-cleaning procedure that is shown to reduce motional heating from ion-trap electrodes. This precleaning treatment, to be implemented immediately before the final assembly and vacuum processing of ion traps, removes surface contaminants remaining after the electrode-fabrication process. We incorporate a multi-angle ion-bombardment treatment intended to clean the electrode surfaces and interelectrode gaps of microfabricated traps. This procedure helps to minimize redeposition in the gaps between electrodes that can cause electrical shorts. We report heating rates in a stylus-type ion trap prepared in this way that are lower by one order of magnitude compared to a similar untreated stylus-type trap using the same experimental setup.
We discuss the design and optimisation of two types of junctions between surface-electrode radiofrequency ion-trap arrays that enable the integration of experiments with sympathetically cooled molecular ions on a monolithic chip device. A detailed description of a multi-objective optimisation procedure applicable to an arbitrary planar junction is presented, and the results for a cross junction between four quadrupoles as well as a quadrupole-to-octupole junction are discussed. Based on these optimised functional elements, we propose a multi-functional ion-trap chip for experiments with translationally cold molecular ions at temperatures in the millikelvin range. This study opens the door to extending complex chip-based trapping techniques to Coulomb-crystallised molecular ions with potential applications in mass spectrometry, spectroscopy, controlled chemistry and quantum technology.
We describe the design, fabrication, and operation of a novel surface-electrode Paul trap that produces a radio-frequency-null along the axis perpendicular to the trap surface. This arrangement enables control of the vertical trapping potential and consequentially the ion-electrode distance via dc-electrodes only. We demonstrate confinement of single $^{40}$Ca$^+$ ions at heights between $50~mu$m and $300~mu$m above planar copper-coated aluminium electrodes. We investigate micromotion in the vertical direction and show cooling of both the planar and vertical motional modes into the ground state. This trap architecture provides a platform for precision electric-field noise detection, trapping of vertical ion strings without excess micromotion, and may have applications for scalable quantum computers with surface ion traps.