Molecular Ions: an Hybrid Atom-Ion Platform to Generate Quantum States

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The recent developments in information technology are having a large impact on the society. One factor in the explosion of new technologies is the rapid increase in computing power, described by Moore's law: processor power doubles every 18 months. This is accompanied by a reduction in the size of the processors. In the near future, the actual processors based on classical treatment of information will reach the quantum limit; the uncertainty principle of quantum mechanics will come into play. Quantum Information Science (QIS) is a new approach to information science that takes advantage of laws of quantum mechanics. New advances in quantum information indicate that devices based on fundamental quantum principles, such as interference and entanglement, can perform certain tasks considerably more efficiently than any classical computer. Efforts in quantum information processing have led to protocols for quantum cryptography, and quantum algorithms. Many platforms have been studied for QIS, such as trapped ions, neutral atoms, Rydberg atoms, atoms in crystals, spin of particles, photons in cavity quantum electrodynamics (QED) or nonlinear optical setups, mesoscopic ensembles, and polar molecules.As the field of quantum information science matures, so do its goals. There is a search for more realistic and better scalable systems, for novel areas of application and stronger cross-fertilization with other areas in physics. A hybrid platform for generating quantum states and for quantum information processing, based on molecular ions will be studied, with an eye towards feasibility, scalability, and connection with other subfields in physics. This hybrid platform shares the advantages of other platforms; the long coherence times of neutral atoms, and strong interactions of trapped ions. The required properties of these systems will be studied in order to identify the best candidates among molecular ions that will allow the Coulomb interactions between atoms to be switched off and on. This will help guide efforts in designing new experimental apparatus for quantum information processing.The main effort relates to quantum information science, namely the possible generation of quantum states, and the implementation of phase gates. First, the use of molecular ions as enablers to design non-trivial states, such as non-local atoms will be explored. Specific species, alkali+alkaline earth and homonuclear alkaline earth diatomic molecular ions will be studied and their properties (energy surfaces, transition moments, hyperfine structure, etc.) computed. Second, arrays of neutral atoms and trapped ions that could be used to effectively create strong long-range interactions that can be switched on and off by using molecular ions as mediators to enable entanglement will be studied, systems, such as combinations of sodium (Na) and calcium (Ca), Na + Ca+, or Ca + Ca+. These new systems will be explored using realistic parameters from careful calculations, to help in understanding complex physical systems, and to predict new phenomena and to generate new theoretical concepts. The exploratory research on quantum computing with molecular ions promises to broaden the scope of QIS and atomic, molecular and optical physics to mesoscopic systems, and condensed matter physics.