Physics World reveals its top 10 breakthroughs for 2010

The award for the Physics World 2010 Breakthrough of the Year goes to two international teams of physicists at CERN, who have created new ways of controlling antiatoms of hydrogen.

Photograph taken inside the antihydrogen facility at CERNThe ALPHA collaboration announced its findings in late November, which involved trapping 38 antihydrogen atoms (an antielectron orbiting an antiproton) for about 170 ms. This is long enough to measure their spectroscopic properties in detail, which the team hopes to do in 2011.

Just weeks later, the ASACUSA group at CERN announced that it had made a major breakthrough towards creating a beam of antihydrogen that is suitable for spectroscopic studies. Our congratulations to both teams.

Also awarded are nine runners (see below) – with second place going to the first direct detection of the spectrum of an exoplanet and third place to the observation of quantum behaviour in an object big enough to be seen with the naked eye.

1st place: Antihydrogen success

The antihydrogen breakthroughs scooped our first prize because it ought now be possible to carry out the first detailed studies of the energy levels in antihydrogen. Any slight differences in the levels compared to ordinary hydrogen could shed light on one of the biggest mysteries in physics – why there is so much more matter than antimatter in the universe.

Photo of the ALPHA team
The ALPHA group is represented by Jeffrey Hangst of Aarhus University in Denmark, who told that the holy grail of antihydrogen studies is measuring the energy of the 1 s to 2 s atomic transitions. This transition in the far-ultraviolet has been measured in hydrogen to an accuracy of two parts in 1014, and making similar measurements on antihydrogen could reveal a violation of charge-parity-time reversal (CPT) symmetry. The discovery of such a violation could also help physicists understand why there is much more matter than antimatter in the universe.

One challenge facing the ALPHA team is accumulating enough antihydrogen to make accurate measurements – however, Hangst said that the team has already trapped “a lot” more than the 38 reported in November. Hangst says that the most difficult part of the five-year ALPHA project has been “learning how to make antihydrogen cold enough to trap”, because it is extremely difficult to make spectroscopic studies on beams.

Photo of some of the ASACUSA team
In December, however, the ASACUSA team announced its ability to create a focused beam of antihydrogen that the researchers believe is suitable for making spectroscopic measurements at microwave energies. This should allow them to look at the hyperfine structure of antihydrogen energy levels and compare them to hydrogen – which could provide evidence of CPT violation.

2nd place: Exoplanet atmosphere laid bare

3rd place: Quantum effects seen in a visible object

4th place: Visible-light cloaking of large objects

5th place: Hail the first sound lasers

6th place: A Bose–Einstein condensate from light

8th place: Towards a Star Wars telepresence

10th place: CERN achieves landmark collisions

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