Principles of Ion Traps

Daniel F. Walls, Gerard J Milburn

Richard Claude Thompson, Kishan Dholakia, J-L Hernandez-Pozos +3 more

A review is given of the use of trapped atomic ions for spectroscopy and for quantum optics. The article discusses the principles of operation of the different types of traps, and their advantages for work in these fields, including the use of laser cooling of trapped ions. Aspects of laser cooling are demonstrated with the help of a numerical simulation program. Then the use of spectroscopic techniques to study the oscillation frequencies of trapped ions is discussed. Finally a number of different experiments illustrating the application of trapped ions to quantum optics are presented.

Hugh A. Klein

M. Niranjan, Anand Prakash, S. A. Rangwala

We evaluate the performance of multipole, linear Paul traps for the purpose of studying cold ion–atom collisions. A combination of numerical simulations and analysis based on the virial theorem is used to draw conclusions on the differences that result, by considering the trapping details of several multipole trap types. Starting with an analysis of how a low energy collision takes place between a fully compensated, ultracold trapped ion and an stationary atom, we show that a higher order multipole trap is, in principle, advantageous in terms of collisional heating. The virial analysis of multipole traps then follows, along with the computation of trapped ion trajectories in the quadrupole, hexapole, octopole and do-decapole radio frequency traps. A detailed analysis of the motion of trapped ions as a function of the amplitude, phase and stability of the ion’s motion is used to evaluate the experimental prospects for such traps. The present analysis has the virtue of providing definitive answers for the merits of the various configurations, using first principles.

Xinfang Zhang, Bao-Quan Ou, Ting Chen +3 more

Scaling up and effective cooling of ions in surface ion trap are central challenges in quantum computing and quantum simulation with trapped ions. In this theoretical study, we propose a versatile surface ion trap. In the manipulation zone of our trap, a symmetric seven-wire geometry enables innate principle-axes rotation of two parallel linear ion chains, which facilitates the cooling of ions along all principle trap axes. To alleviate contaminating the manipulation zone during ion loading, a symmetric five-wire geometry is designed as the loading zone. And a "fork junction" connects the loading and manipulation zones, which also enables the shuttling and reordering of ions. A multi-objective optimization procedure suitable for arbitrary junction designs is described in detail, and we present the corresponding optimal results for the key components of our trap. The proposed versatile trap can be used in the construction of large-scale ion quantum processors. The trap also can be used as the multi-ion-mixer or the efficient ion beam splitter, which has the potential applications in quantum simulation and quantum computing, the research of 2D dimensional ion crystals and the guides of quantum microscope, like an electron beam splitter used for quantum matter-wave optics experiments. Interesting topics involving the spin-spin interactions between two ion chains can also be simulated in our trap.

Daniel F. Walls, Gerard J Milburn