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Atom & Ion Trapping

Many of the experiments at CQT rely on the trapping of atoms and ions because it allows reliable manipulation of the atomic systems we work with, helping us study quantum effects in these systems. Atoms and ions can be trapped by a variety of techniques. Neutral atoms can be confined by the oscillating electric fields from a laser (the optical dipole force trap) and/or static magnetic fields. Ions can be confined by a combination of static and radio frequency fields.

Optical dipole force traps make use of the electric dipole moment of an atom. A trapping force can be realized by a high intensity laser: atoms are attracted to the regions of highest intensity such as at the laser's focus. By using a tightly focused laser, researchers at CQT have been able to strongly confine a single atom and substantially improve the interaction between the atom and a single quantum of light. Additionally, interference patterns can be used to form one-, two-, and three-dimensional lattices of traps. Researchers in CQT's Microtraps group are using a one-dimensional lattice potential as an elevator for cold atoms to deterministically transport atoms into a high finesse optical cavity. Additionally, lattice potentials can be used to form large arrays of atoms. Such arrays may be used to simulate and provide insights into the behaviour of more complicated condensed matter systems. Experiments are being carried out at CQT with fermions in lattices.

Magnetic traps make use of the magnetic dipole moment of an atom and are routinely used for creating and working with quantum degenerate gases, as in CQT's Quantum Matter group. Since magnetic fields are created by current-carrying conductors, micro-electronic circuits can be used to form the traps. Researchers at CQT are also using these so-called “atom chips" because they provide great flexibility in the design of trapping potentials with the possibility of integration with optical waveguides, fibres, or micro-cavities.

Ion traps exploit the strong electric force experienced by an ion because of its charge. These traps are well suited to trapping individual (charged) atoms. The strength of the force means that ions can be trapped for several days or even longer. Ion traps provide an unprecedented level of control over individual atoms and they are consequently a strong candidate for use in quantum information processing. Researchers at CQT are currently investigating the use of ion traps with cavity QED as a means to interface photonic and atomic qubits. Since ion traps only rely on the charge of the ion they can be also used to trap molecular particles. Researchers at CQT are also investigating molecular ions for metrology and quantum information applications.