Description

The laboratory at the UGR has been completed in 2015. The setups are described in the following:

  • The lasers system is placed on an optical table with dimensions 2.5 m x 1.5 m, and it comprises eight tunable diode lasers (DL Pro TOPTICA Photonics) with external-cavity resonator in Littrow configuration. Two lasers are used for cooling using the electric-dipole transition at 397 nm of the 40Ca+ ion. Four lasers at 866 nm are required to restore the cooling when it is interrupted via the decay from 42P1/2 to the dark state 32D3/2, which can occur with a probability of 7%. Another two lasers at 854 nm, will be used to drive the transition 32D5/2 to 42P3/2, since the state can be populated from 42P1/2 with a probability that increases with the strength of the magnetic field with a branching ratio relative to the main decay proportional to the square of B, as measured by the group of Prof. Richard Thompson. In this scenario, one needs four more laser beams with a wavelength of 854 nm, to pump from the state 32D5/2 to 42P3/2 in the 7-T magnetic field. Such laser beams will be generated by means of an electro-optical modulator from the two beams provided by the diode lasers. A microwave signal generator with frequency range from 9 kHz to 40 GHz with an amplifier is used to feed the EOM. The wavelength of the lasers is measured and stabilized using a Fizeau-based wavelength meter (HighFinesse WSU-10) with an absolute accuracy of 10 MHz (3 sigma). A stabilized HeNe laser (632.9909463 nm) with very high frequency stability provides the reference value to calibrate the wavemeter. The setup to couple the 12 laser beams needed for the Penning trap experiment has been completed in January 2016.
  • A Penning traps beamline which comprises a laser-desorption ion source, a transfer section, a Penning traps system and a time-of-flight section for identification. The laser desorption ion source to inject ions externally in the trap, is in operation since 2013. First trapping was already accomplished in 2014 and, by the end of 2014, it was possible to obtain the so-called cooling resonance for 40Ca+ ions and other ion species. The Penning trap system consists of two traps, one made of stack of cylinders for preparation and the other with a novel geometry to study laser cooling in the 7 T magnetic field. The measurement trap will be substituted by the end of 2016 by the double-Penning-(micro)-trap system, in the last stage of construction.
  • A Paul trap experiment where the Doppler limit on a single laser-cooled ion has been reached in 2015. This trap has an original geometry, which was taken as reference for the design and construction of the micro-trap. The trap is made of two sets of three concentric rings centered on the z-axis.
  • There is in addition a two-stage cold head cryocooler where tests at cryogenic temperatures (4 K) of the electronics have been carried out, and in December 2015 a frequency comb was installed in the laboratory.