A High-optical-access Ion Trap And Its Application

Cold atom systems,including neutral atom,trapped ions,as well as cold hybrid ion-atom systems,are ideal platforms to explore scalable quantum simulation and quantum computing researches.In these systems,optical cooling,trapping,and quantum state manipulation provided by lasers are widely used,which are the most basic and important methods for modern atomic,molecular,and optical(AMO)experiments.One of the most powerful and urgently needed tools compatible with trapped ion is the programmable optical tweezer,which has been widely utilized in cold neutral atoms and molecules for decades.Optical tweezers are high focused off-resonant dipole traps with a beam waist down to about a few microns.Programmable optical tweezer ar-rays can be applied,for example,by a high numerical aperture(NA)objective and an acoustooptic deflector(AOD),to address individual atoms or ions.Employing optical tweezers in an ion trap has several major significances.Firstly,it allows us to opti-cally trap ions in the absence of radio-frequency(RF)field,which helps to get rid of the heating due to RF micromotion.Secondly,it allows us to trap single neutral atoms optically and spatially overlap them with single ions trapped electrically at ultralow temperature,which will eventually pave the way towards coherent chemistry with full quantum control.Thirdly,it allows us to engineer localized phonon modes of indi-vidual ions pinned by optical tweezers in a long string,which is able to address the challenge of scale and parallel quantum computations with long one-dimensional ion strings or two-dimensional ion crystals.However,an optical tweezer in the ion trap requires an additional high NA objective to the already complex optical configurations in the trapped ion system.For most ion traps,it is difficult or not feasible to have enough optical access for high focused Raman beams,programmable optical tweezer arrays,efficient fluorescence collection simultaneously.It is always crucial to optimize the optical accessibility of the ion trap setup,especially the hybrid atom-ion quantum system,to enhance these control capabilities.Currently,the optical accessibility of the trapped ion system,especially the hybrid atom-ion quantum system,is greatly limited by the conventional bulky stainless steel vacuum chamber.To address this problem,in this thesis we present the design,fabraication,test and application of a new ion trap with high opticall access.Here,we report the fabrication of integrating a compact segmented-blade ion trap into a glass vacuum cell.With a distance of 15 mm from the trap center to four outside surfaces of the glass cell,the system enables us to install four high numerical aperture(NA)lenses(with two NA≤0.32 lenses and two NA≤0.66 lenses)and obliquely apply multiple laser beams around the glass cell simultaneously.The high NA lenses can be used to generate laser spots below 2 μm and collect fluorescence of single atoms,which are applicable to optical dipole trap,single atoms addressing,state manipulation,and fluorescence detection.Both DC blades are segmented into five electrodes,which en-able the precise control of the motion of the ions.By using laser ablation and optical ionization methods,we have successfully loaded a one-dimensional 174Yb+and 171 Yb+ion crystal in the trap,realized Doppler cooling of the ions and verified the trapping stability.We introduce the design concept and fabrication methods of this trap in detail,along with a series of numerical simulations and experimental characterizations of its performance.This compact high-optical-access trap setup can integrate multiple ap-plications for trapped ions,optical tweezers,and neutral cold atoms in one apparatus,which not only can be used as an extendable module for quantum information process-ing,but also facilitates experimental studies on quantum chemistry in a cold hybrid ion-atom system.We achieve a quantum simulator based on the trapped ion and experimentally iden-tify the first non-trivial zero of the Riemann zeta function and the first two non-trivial zeros of the Polya’s function using a novel Floquet method.Through properly designed periodically driving functions,the zeros of these functions are characterized by the oc-currence of crossings of quasi-energies when the dynamics of the system are frozen.Ion traps feature long coherence times and high fidelity of both operation and detection,which are critical to observe the CDT because dozens of driving cycles are necessary.The first Riemann zeros is indentified to be 14.3±0.1,in good agreement with the exact value 14.1347.Our study provides the first experimental realization of the Riemann ze-ros in a quantum system,which may provide new insights into the connection between the Riemann function and quantum physics.