AP-Seminar: Towards a quantum logic detector for single (anti-)proton magnetic resonance

Significant progress has been made recently towards a test of CPT invariance based on a comparison between the proton's and antiproton's magnetic moment. In particular, two groups have achieved detection of single proton spin states by pushing to the limit techniques developed in the context of single-electron spin resonance [Ulmer et al. PRL 106, 253001 (2011); J. DiSciacca and G. Gabrielse, Phys. Rev. Lett. 108, 153001 (2012)]. At Hannover and Braunschweig, we are exploring an alternative, quantum logic approach to single (anti-) proton spin resonance [Heinzen and Wineland, PRA 42, 2977 (1990); Wineland et al., J. Res. NIST 103, 259 (1998)]. The basic idea is to map the spin state of the proton into its motion using a rf sideband pulse, and then to transfer it to an atomic ion held in a neighboring trap through the mutual Coulomb interaction. The mapped (anti-)proton spin information could then be read out using fluorescence detection on the atomic ion. The realization builds on two key steps demonstrated during my work as a guest researcher at NIST, namely the coupled traps technique [Nature 471, 196 (2011)] and near-field microwave quantum logic [Nature 476, 181 (2011) ]. We discuss potential ion trap geometries, state transfer schemes, laser excitation schemes for the atomic ion for high magnetic fields and magnetic field calibration techniques.