CERN Accelerating science

The fractional resolution achieved in our precision tests of matter–antimatter symmetry – comparing the fundamental properties of antiprotons and protons – is improving rapidly. The most precise test of CPT invariance in the baryon sector, done in our trap system, has reached a fractional resolution of 16 parts per trillion, with clear potential for further improvement by at least one to two orders of magnitude.

Two BASE members have recently received international awards for their contributions to our experiments.

At BASE, we develop and operate advanced Penning-trap systems to study the properties of single antiprotons with world-leading precision. Our goal is to compare matter and antimatter at the most fundamental level and to test the symmetries underlying the Standard Model.

We are thrilled and deeply honored that our work on the first non-destructive coherent spectroscopy of a single antiproton spin has been selected as one of the Top 10 Breakthroughs of the Year by Physics World. This recognition highlights a major step forward in precision antimatter physics, achieved through the dedication and creativity of the entire BASE team.

We’re excited to share this milestone with the global scientific community—and even more excited for what comes next.

In a major milestone for quantum physics and antimatter research, we at BASE have demonstrated the first coherent spectroscopy with a single antiproton spin. By keeping a single antiproton oscillating coherently between the "spin-up" and the "spin-down" states for 50 seconds, we've demonstrated quantum control over a fundamental antimatter particle — something never done before.

In a major milestone for antimatter research, we have – for the first time – successfully transported protons outside an antimatter laboratory using our fully autonomous, open, mobile Penning trap system BASE-STEP. This pioneering technology enables the relocation of charged particles without the need for continuous external power.

In an article, published today in Physical Review Letter, we demonstrate efficient sub-thermal cooling of the modified cyclotron mode of a single trapped antiproton and reach particle temperatures below 200 mK in preparation times shorter than 500 s. This corresponds to the fastest resistive single-particle cyclotron cooling to sub-thermal temperatures ever demonstrated.

In an article, published today in Physical Review Letter, we demonstrate a new temperature record for image-current mediated sympathetic cooling of a single proton in a cryogenic Penning trap by laser-cooled beryllium ions. In our experiments we reach an axial mode temperature of 170 mK, corresponding to a 15-fold improvement compared to the best value achieved in previous experiments.

In a paper published today in Nature, we report on the most precise comparison between a fundamental property of protons and antiprotons. Analysing a total of about 24000 proton and antiproton cyclotron frequency measurements, taken over the course of one year and half, we found that the charge-to-mass ratios of protons and antiprotons are identical to within a record experimental uncertainty of 16 parts per trillion, see Fig. 1.

Today, we report in Nature on the first sympathetic cooling of a single trapped proton, using laser-cooled beryllium ions stored in a spatially separated trap. The energy exchange between the proton and the laser-cooled ions is mediated by image currents induced by the ions in the trap electrodes, transmitted through a superconducting LC circuit that connects the traps (see Figure 1).