Characterization of surface ion trap structures for quantum information processing.
Susan Clark, Craig Robert Clark, Raymond A. Haltli, Jonathan David Sterk, Matthew G. Blain, Daniel Stick, Christopher P. Tigges, Peter Maunz, Boyan Tabakov
Scaling trapped ion quantum information processing to large numbers of qubits relies on micro-fabricated traps optimized for the applications in quantum computing and quantum simulation.High trap frequencies and excellent optical access are the key features necessary for quantum information processing that are realized in Sandia's bowtie shaped High Optical Access trap.For quantum simulations long equidistant chains of ions, and ring-shaped crystals are of interest.Here, we demonstrate a chain of approximately 350 ions in a highly symmetric ring trap. Ring Trap10 mm Motivation • Large equidistant ion crystal • RF potential is sufficient to trap ion chain • Periodic boundary conditions • Possible applications: • phase transitions (E.
Scaling trapped ion quantum information processing to large numbers of qubits relies on micro-fabricated traps optimized for the applications in quantum computing and quantum simulation.High trap frequencies and excellent optical access are the key features necessary for quantum information processing that are realized in Sandia's bowtie shaped High Optical Access trap.For quantum simulations long equidistant chains of ions, and ring-shaped crystals are of interest.Here, we demonstrate a chain of approximately 350 ions in a highly symmetric ring trap. Ring Trap10 mm Motivation • Large equidistant ion crystal • RF potential is sufficient to trap ion chain • Periodic boundary conditions • Possible applications: • phase transitions (E.
Microfabricated segmented surface ion traps are one viable avenue to scalable quantum information processing. At Sandia National Laboratories we design, fabricate, and characterize such traps. Our unique fabrication capabilities allow us to design traps that facilitate tasks beyond quantum information processing. The design and performance of a trap with a target capability of storing hundreds of equally spaced ions on a ring is described. Such a device could aid experimental studies of phenom- ena as diverse as Hawking radiation, quantum phase transitions, and the Aharonov - Bohm effect. The fabricated device is demonstrated to hold a \u223c 400 ion circular crystal, with 9 μm average spacing between ions. The task is accomplished by first characterizing undesired electric fields in the trapping volume and then designing and applying an electric field that substantially reduces the undesired fields. In addition, experimental efforts are described to reduce the motional heating rates in a surface trap by low energy in situ argon plasma treatment that reduces the amount of surface contaminants. The experiment explores the premise that carbonaceous compounds present on the surface contribute to the anomalous heating of secular motion modes in surface traps. This is a research area of fundamental interest to the ion trapping community, as heating adversely affects coherence and thus gate fidelity. The de- vice used provides high optical laser access, substantially reducing scatter from the surface, and thus charging that may lead to excess micromotion. Heating rates for different axial mode frequencies are compared before and after plasma treatment. The presence of a carbon source near the plasma prevents making a conclusion on the observed absence of change in heating rates.
Trapped-ion quantum information experiments have reached ion numbers where precise control of multiple ion chains is necessary, resulting in a growing need for high-performance microfabricated surface traps.With Sandia's High Optical Access (HOA) trap, which boasts high trap frequencies and long trapping times, we have achieved the first single-qubit gates with a diamond norm below a rigorous fault tolerance threshold [1,2], and a two-qubit Mølmer-Sørensen gate [3] with a process fidelity of 99.58(6).We also demonstrate novel control techniques, afforded by precise manipulation over the curvature of the trapping potential, that support continuous rotation of principal axes while maintaining constant secular frequencies.
We describe a novel monolithic ion trap that combines the flexibility and scalability of silicon microfabrication technologies with the superior trapping characteristics of traditional four-rod Paul traps. The performace of the proposed microfabricated trap approaches that of the macroscopic structures. The fabrication process creates an angled through-chip slot which allows backside ion loading and through-laser access while avoiding surface light scattering and dielectric charging. The trap geometry and dimensions are optimized for confining long ion chains with equal ion spacing [G.-D. Lin, et al., Europhys. Lett. 86, 60004 (2009)]. Control potentials have been derived to produce linear, equally spaced ion chains of up to 50 ions spaced at 10 um. With the deep trapping depths achievable in this design, we expect that these chains will be sufficiently long-lived to be used in quantum simulations of magnetic systems [E.E. Edwards, et al., Phys. Rev. B 82, 060412(R) (2010)]. The trap is currently being fabricated at Georgia Tech using VLSI techniques.
Qubit systems based on trapped ultracold ions win one of the leading positions in the quantum computing field, demonstrating quantum algorithms with the highest complexity to date. Surface Paul traps for ion confinement open the opportunity to scale quantum processors to hundreds of qubits and enable high-connectivity manipulations on ions. To fabricate such a system with certain characteristics, the special design of a surface electrode structure is required. The depth of the trapping potential, the stability parameter, the secular frequency and the distance between an ion and the trap surface should be optimized for better performance. Here, we present the optimized design of a relatively simple surface trap that allows several important high-fidelity primitives: tight ion confinement, laser cooling, and wide optical access. The suggested trap design also allows us to perform an important basic operation, namely, splitting an ion chain into two parts.
Using an ensemble of ions to register one qubit each, the so-called trapped ion quantum computer could serve as a universal computing machine, with the advantages in speed and power that a quantum device could bring. However, actually making a suitably large trap is far from trivial. The authors microfabricate a ring-shaped ion trap and demonstrate its storage of 400 evenly spaced calcium ions. Its circularly symmetric trapping potential furthermore enables fundamental experiments on e.g. simulated Hawking radiation or the Aharonov-Bohm effect.
Trapped ions are among the top candidates for realizing high fidelity gate operations for quantum computation as well as other applications including quantum simulation and sensing [1]. However, scaling these systems up to the number of qubits required to solve interesting problems with conventional macroscopic traps quickly becomes intractable. To overcome the scalability challenge, advanced microfabrication techniques have been developed to support a variety of complex electrode layouts, allowing for precise and dynamic control of confining potentials. Using Sandia’s microfabricated surface ion traps, which feature low heating rates, high trap frequencies, and long trapping times, we demonstrate novel classical control techniques that employ parametric voltage solutions for elegant composition of shuttling operations and accurate control over the curvature of the confining potential. To demonstrate the viability of Sandia's microfabricated ion traps for quantum information processing, we’ve realized of high-fidelity single-qubit gates below a rigorous fault tolerance threshold for general noise [2,3] and two-qubit Mølmer-Sørensen gates with a process fidelity of 99.58(6)%.