Triple Resonant Four-Wave Mixing Boosts the Yield of Continuous Coherent Vacuum Ultraviolet Generation

Abstract

Efficient continuous-wave four-wave mixing by using three different fundamental wavelengths with individual detunings to resonances of the nonlinear medium is shown. Up to 6 μW of vacuum ultraviolet light at 121 nm can be generated, which corresponds to an increase of three orders of magnitude in efficiency. This opens the field of quantum information processing by Rydberg entanglement of trapped ions.

Rydberg Excitation of a Single Trapped Ion

“…Rydberg ions in Coulomb crystals will allow for shaping localized vibrational modes for quantum simulation and fast parallel execution of quantum gates [16,17]. Further applications are dynamical structural phase transitions and non-equilibrium dynamics driven by Rydberg excitations [18].Two major challenges have to be met in order to access the unique features of Rydberg ions: Firstly, excitation energies are large compared to the case of neutral atoms such that either a vacuum ultraviolet (VUV) laser source [9,19] or multi-step excitation [20] with UV lasers is required. Secondly, the large polarizability of Rydberg states makes them very susceptible to residual electric fields in the Paul trap, where an oscillating field with quadrupolar geometry and gradients of about 10 7 -10 9 V/m 2 provides stable trapping conditions.…”

Mode shaping in mixed ion crystals of 40Ca2+ and 40Ca+

“…A detailed description of this laser can be found in [17,11]. Coherent VUV radiation at 121.26 nm is produced by triple resonant four-wave mixing in mercury with three fun-damental waves at 254 nm, 408 nm and 540 nm (see Fig.…”

“…We generate mixed Coulomb crystals consisting of ions with a large difference in charge-to-mass ratio by ionizing single 40 Ca + ions with a vacuum ultraviolet (VUV) source [17]. The wavelength of the VUV source can be changed from ionisation to Rydberg excitation wavelength and a very similar excitation scheme is used in both cases.…”

The Production and Study of Cold Antiprotons and Antihydrogen

“…Starting in the Hänsch Laboratory in Garching, and then moving to the Walz Laboratory in Mainz, our collaborators continue to improve a source of Lyman alpha radiation suitable for laser cooling and for 1s-2p spectrosocpy [46,47,48,49,50,51,52,53,54,55]. Four-wave mixing is used to generate continuous, coherent Lyman alpha radiation at 121.5 nm.…”

“…Up to 6 µW of coherent UV light near to the Lyman alpha frequency was recently reported using triply resonant four-wave mixing [54], and the robustness of the source continues to improve. Enough power to cool trapped H and for initial H spectroscopy [19] has already been demonstrated.…”