Plasma Physics and Nuclear Fusion Laboratory

Atomic Particle Trapping and Frequency Standards Group

Ion trapping is the basic tool employed for different applications by more than 40 participating groups from all Europe and Israel. Samples ranging from a single ion up to 107 particles can be confined for several hours or even months in a vacuum chamber with essentially no interactions with either the walls or other particles. The main goal of this Action is to consider, from different points of view, the basic problems encountered in ion trapping and control, and to promote a Europe-wide collaborative effort in tackling these problems. The insight gained into ion trapping devices and interactions on different size scales will enable the pursuit of, for instance, a scalable approach to quantum information processing. Investigations can be divided into four major topics:

• Developing technology for ion trapping experiments. While the research goals are various for different ion trapping groups, many of the technological challenges are the same. Examples include the development of complex computer controlled frequency and pulse sources, the development of microfabricated ion traps, the implementation of novel cooling methods for species which cannot be laser cooled (including molecular ions), and the quantum-state preparation of trapped ions.
• Storage and cooling at different trap size scales. Increase of ion numbers to large cloud sizes and, at the other extreme, reduction of trap dimensions for use with individually resolved ions, pave the way for an extension of a number of applications beyond the frontiers of existing knowledge. Measurement of heating rates in a variety of ion trap structures with different ion species may shed more light on this phenomenon. Collating an inventory of existing experimental devices in a ‘data base’ and the development of new devices will allow the development of a scalable approach to ion trapping devices.
• Interaction of ions with electromagnetic radiation. Light, and in particular laser light, allows the state preparation, cooling and manipulation of the stored ions, as well as measurements of metrological interest. Novel experimental protocols can be theoretically developed and validated in a wide variety of experiments.
• Investigation of atomic-molecular ion and ion-neutral interactions to elucidate the scattering and chemical dynamics at ultralow collision energies. Such studies are of considerable interest for the development of novel sympathetic cooling schemes and for the characterisation of quantum- mechanical effects that influence chemical reactivity at very low temperatures.

Recent experiments and theoretical advances have focused on the possibility to control or engineer atomic, molecular and quantum optics states, in a coherent manner. Nonlinear states play an important role in quantum optics. With respect to nonclassical effects, coherent states define the limit between classical and non-classical effects. Particular representations of these coherent states show up as stationary states of the dynamics of an ion which interacts in an adequate manner with the laser radiation.

The directions of action taken within the framer of the project consisted in the investigation of theoretical and experimental limits of applying the coherent control methods to trapped ions, in order to:

• generate and analyse classical states of motion
• generate and analyse nonclassical states, such as entangled, coherent, Schrodinger-cat and Fock states, which enhance the signal-to-noise ratio in spectroscopy
• study multiparticle dynamics in ion traps along with numerical simulations of the associated ordering processes
• study and design new ion trap geometries which would increase the signal-to-noise ratio and minimize the disturbing effects, with direct consequences on the long term stability of trapped particles, thus enabling quantum computing and realization of time-frequency standards based on trapped atomic ions with enhanced properties compared to present day ones

• systematic experimental studies on the plasma-RF field energy transfer in the laboratory frame
• theoretical studies on the plasma-electromagnetic field interactions aimed to develop the mathematical models able to describe properly the energy transfer phenomena
• study of the effects of the plasma-RF field energy transfer on the plasma antenna operation
• theoretical studies and experimental tests on the possibility to use the energy transferred from plasma to the RF field for practical purposes

Rapid progress development of atomic frequency standards has recently made it possible to perform in-situ laboratory searches for present-day variation of fundamental constants. The availability of highly accurate, reliable, and robust measurement technologies is very important to research and development, manufacturing quality control, metrology and marketplace exchange. In fact, electrical quantities are the common currency of measurements; that is, many non-electrical quantities are converted into electrical quantities to facilitate measurement using electronic instrumentation. To achieve these goals, a great deal of attention was paid to quantum phenomena. They enable relating electrical quantities to unvarying fundamental atomic constants, such as the charge of an electron. Continued success in the implementation of electrical standards based on quantum phenomena could result in a future redefinition of the System of Units (SI). Based on recent experiments and results, it is considered that electromagnetic traps are ideal candidates for quantum metrology measurements.

• optimize trap geometries and minimize parasitic effects with an aim to enhance the signal-to-noise ratio in spectroscopy
• study nonlinear parametric oscillators as natural models for ion dynamics in RF traps
• implement quantum logic gates by manipulating trapped charged particles through interaction with laser fields and quantized cavity fields
• test these new trap geometries and use them in environment monitoring
• study particle dynamics in electromagnetic traps operating in air, along with numerical simulations of the associated ordering processes.