Robust Microwave-Dressed States with Trapped Ions

TYPEQuantum Information Seminar
Speaker:Alex Retzker
Affiliation:Universitat Ulm
Location:Lewiner Seminar Room (412)
Abstract:Laser cooled atomic ions confined in an electrodynamic cage have been very successfully used for quantum information science (QIS). For ion trap QIS, the use of laser light for coherent manipulation gives rise to fundamental issues, notably, unavoidable spontaneous emission that destroys coherences, and to technical difficulties in steering and accurately controlling a large number of laser beams that hinder scalability. The difficulty in cooling several ions to their motional ground state, and the time needed for such a process in the presence of spurious heating of Coulomb crystals further limit the fidelity of quantum logic operations in laser-based quantum gates, and thus present difficulties for scalability. Recently, laser-less addressing of ions and Magnetic Gradient Induced Coupling (MAGIC) between ion spins and their motion using radio-frequency radiation has been demonstrated for the first time. By using MAGIC, and thus avoiding the use of laser light for coherent manipulation, technological and fundamental hurdles on the path towards a scalable trapped ion quantum processor or simulator can be overcome. An issue that MAGIC shares with optical schemes is the use of magnetic field sensitive states that are susceptible to ambient noise fields limiting their coherence time. Here, we report on the progress of ongoing experiments of a novel idea to prolong coherence times with 171Yb+ ions showing that the use of microwave-dressed states as qubits stabilizes them against magnetic field fluctuations and, thus, enhances their coherence time.