No Arabic abstract
We present methods to manipulate and detect the motional state and the spin state of a single antiproton or proton which are currently under development within the BASE (Baryon Antibaryon Symmetry Experiment) collaboration. These methods include sympathetic laser cooling of a single (anti-)proton using a co-trapped atomic ion as well as quantum logic spectroscopy with the two particles and could be implemented within the collaboration for state preparation and state readout in the antiproton $g$-factor measurement experiment at CERN. In our project, these techniques shall be applied using a single $^9text{Be}^+$ ion as the atomic ion in a Penning trap system at a magnetic field of 5 T. As an intermediate step, a controlled interaction of two beryllium ions in a double-well potential as well as sympathetic cooling of one ion by the other shall be demonstrated.
Current experimental efforts to test the fundamental CPT symmetry with single (anti-)protons are progressing at a rapid pace but are hurt by the nonzero temperature of particles and the difficulty of spin state detection. We describe a laser-based and quantum logic inspired approach to single (anti-)proton cooling and state detection.
We discuss laser-based and quantum logic inspired cooling and detection methods amenable to single (anti-)protons. These would be applicable e.g. in a g-factor based test of CPT invariance as currently pursued within the BASE collaboration. Towards this end, we explore sympathetic cooling of single (anti-)protons with atomic ions as suggested by Heinzen and Wineland (1990).
We present first indications of sympathetic cooling between two neutral, optically trapped atomic species. Lithium and cesium atoms are simultaneously stored in an optical dipole trap formed by the focus of a CO$_2$ laser, and allowed to interact for a given period of time. The temperature of the lithium gas is found to decrease when in thermal contact with cold cesium. The timescale of thermalization yields an estimate for the Li-Cs cross-section.
We demonstrate sympathetic sideband cooling of a $^{40}$CaH$^{+}$ molecular ion co-trapped with a $^{40}$Ca$^{+}$ atomic ion in a linear Paul trap. Both axial modes of the two-ion chain are simultaneously cooled to near the ground state of motion. The center of mass mode is cooled to an average quanta of harmonic motion $overline{n}_{mathrm{COM}} = 0.13 pm 0.03$, corresponding to a temperature of $12.47 pm 0.03 ~mu$K. The breathing mode is cooled to $overline{n}_{mathrm{BM}} = 0.05 pm 0.02$, corresponding to a temperature of $15.36 pm 0.01~mu$K.
We trap cold, ground-state, argon atoms in a deep optical dipole trap produced by a build-up cavity. The atoms, which are a general source for the sympathetic cooling of molecules, are loaded in the trap by quenching them from a cloud of laser-cooled metastable argon atoms. Although the ground state atoms cannot be directly probed, we detect them by observing the collisional loss of co-trapped metastable argon atoms using a new type of parametric loss spectroscopy. Using this technique we also determine the polarizability ratio between the ground and the metastable 4s[3/2]$_2$ state to be 40$pm6$ and find a polarisability of (7.3$pm$1.1) $times$10$^{-39}$ Cm$^2/$V for the metastable state. Finally, Penning and associative losses of metastable atoms, in the absence of light assisted collisions, are determined to be $(3.3pm 0.8) times 10^{-10}$ cm$^3$s$^{-1}$.