Physics World reveals its top 10 breakthroughs for 2010

[Henk Elegeert]

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Physics World reveals its top 10 breakthroughs for
2010<http://physicsworld.com/cws/article/news/44618>

Dec 20, 2010

It was a tough decision, given all the fantastic physics done in 2010. But
we have decided to award the *Physics World* 2010 Breakthrough of the Year
to two international teams of physicists at CERN, who have created new ways
of controlling antiatoms of hydrogen.
 [image: Breakthroughs at
CERN]<http://images.iop.org/objects/phw/news/14/12/18/break1.jpg>
Winner: antihydrogen breakthroughs at
CERN<http://images.iop.org/objects/phw/news/14/12/18/break1.jpg>

The 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.

We have also awarded nine runners-up mentions (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.
[image: Photo of the ALPHA
team]<http://images.iop.org/objects/phw/news/14/12/18/break2.jpg>
The ALPHA team celebrates<http://images.iop.org/objects/phw/news/14/12/18/break2.jpg>

The ALPHA group <http://physicsworld.com/cws/article/news/44343> is
represented by Jeffrey Hangst of Aarhus University in Denmark, who told *
physicsworld.com* 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.
[image: Photo of some of the ASACUSA
team]<http://images.iop.org/objects/phw/news/14/12/18/break3.jpg>
Some of the ASACUSA team at
CERN<http://images.iop.org/objects/phw/news/14/12/18/break3.jpg>

In December, however, the ASACUSA
team<http://physicsworld.com/cws/article/news/44561>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.

ASACUSA team leader Yasunori Yamazaki of the RIKEN laboratory in Japan told
*physicsworld.com* that its next step is to make their "antihydrogen beam
from a strong non-uniform magnetic field region where it is produced and
into a microwave cavity for analyses in a magnetic-field-free region to
realize high-precision spectroscopy". He adds that the physicists are "an
inch away" from extracting the beam and "several inches away" from making
spectroscopic measurements. "I hope we can start to work on the spectroscopy
next year after the confirmation of an antihydrogen beam," he says.

Perhaps the most exciting aspect of both projects is that there is no
definitive theoretical prediction of how (or indeed if) CPT-violation will
occur in the hydrogen-antihydrogen system. The antihydrogen experiments will
begin again at CERN in May, so look forward to exciting results – and
perhaps a few surprises from both groups.
2nd place: Exoplanet atmosphere laid
bare<http://physicsworld.com/cws/article/news/41396>

Second place in our list of top breakthroughs for 2010 goes to a team of
astronomers in Canada and Germany who have made the first direct measurement
of the atmospheric spectrum of a planet outside our solar system. Markus
Janson of the University of Toronto and colleagues used the European
Southern Observatory (ESO) Very Large Telescope (VLT) to study the
atmosphere of the exoplanet HR 8799, which is 130 light-years from Earth.
Although this particular exoplanet shows no signs of life, the ability to
make such measurements is an important step forward in the search for life
elsewhere in the universe.
3rd place: Quantum effects seen in a visible
object<http://physicsworld.com/cws/article/news/42019>
[image: Micrograph of the
resonator]<http://images.iop.org/objects/phw/news/14/12/18/quantum1.jpg>
Resonator <http://images.iop.org/objects/phw/news/14/12/18/quantum1.jpg>

In what is an important step towards testing Schrödinger's cat paradox,
physicists at the University of California, Santa Barbara have bagged third
place in our top 10 by observing true quantum behaviour in a macroscopic
object big enough to be seen with the naked eye. Andrew Cleland and crew
reduced the amplitude of the vibrations in a resonator by cooling it down to
below 0.1 K. They were then able to create a superposition state of the
resonator where they simultaneously had an excitation in the resonator and
no excitation in the resonator. "This is analogous to Schrödinger's cat
being dead and alive at the same time," says Cleland. This is the first time
this feat has been achieved and it could shed light on the mysterious
boundaries between the classical and quantum worlds.
4th place: Visible-light
cloaking<http://physicsworld.com/blog/2010/12/now_you_see_itnow_you_see_it_a.html>

Fourth place on our list is a last-minute entry and goes to two independent
teams of physicists who have just published preprints claiming to have built
the first invisibility cloaks that can hide large objects from visible
light. Now George Barbastathis and colleagues at the Massachussets Institute
of Technology and the University of Singapore report the cloaking of 2D
millimeter-sized objects. Meanwhile Shuang Zhang and team at the University
of Birmingham, Imperial College and the Technical University of Denmark have
managed to cloak millimeter-sized 3D objects from prying eyes. Unlike most
other cloaks that use artificial metamaterials, both cloaks use natural
calcite crystals.
5th place: Hail the first sound
lasers<http://physicsworld.com/cws/article/news/41857>

Two independent groups of physicists have been jointly awarded fifth place
after they unveiled the first phonon "lasers". These emit coherent sound
waves in much the same way as lasers emit coherent light waves. One team was
led by Tony Kent at the University of Nottingham in the UK and the other by
Ivan Grudinin at Caltech. One of the devices emits sound at about 400 GHz
while the other operates in the megahertz range. As sound penetrates most
materials, the lasers could be used to obtain 3D images of tiny
nanostructures.
6th place: A Bose–Einstein condensate from
light<http://physicsworld.com/cws/article/news/44412>
[image: Bonn physicists and their photon
BEC]<http://images.iop.org/objects/phw/news/14/12/18/bec1.jpg>
The first photon BEC<http://images.iop.org/objects/phw/news/14/12/18/bec1.jpg>

Many physicists believed it could not be done, but now a team in Germany has
created a Bose–Einstein condensate (BEC) from photons, earning them the
sixth slot. BECs are formed when identical bosons – particles with integer
spin – are cooled until all particles are in the same quantum state.
Although photons are the most common boson of them all, they are easily
created or destroyed when they interact with other matter – making it very
difficult to cool photons to form a condensate. But that did not deter
Martin Weitz and colleagues at the University of Bonn, who got round this
problem by continuously pumping the BEC with a laser to make up for lost
photons. Beyond the pure chutzpah of making the BEC, the breakthrough could
actually help boost the performance of solar cells.
7th place: Relativity with a human
touch<http://physicsworld.com/cws/article/news/43833>

Seventh place in our league table goes to physicists in the US who have
shown us the human face of relativity. James Chin-Wen Chou and colleagues at
the National Institute of Standards and Technology (NIST) used two of the
world's most accurate optical clocks to show that time speeds up in a clock
that is hoisted a mere 33 cm above the other. They also saw time slow down
in a clock moving less than about 35 km/h relative to its twin. While
there's nothing groundbreaking about the physics – Einstein's theories of
relatively are on very solid ground – it's reassuring that its effects can
be seen at human distances and speeds.
8th place: Towards a *Star Wars*
telepresence<http://physicsworld.com/cws/article/news/44240>
[image: A refreshable, holographic image of an F-4 Phantom
Jet]<http://images.iop.org/objects/phw/news/14/12/18/holo1.jpg>
F-4 Phantom holograph<http://images.iop.org/objects/phw/news/14/12/18/holo1.jpg>

Anyone who uses physics to realize a scene from *Star Wars* deserves a place
in our top 10, which is why Nasser Peyghambarian and collegues at the
University of Arizona and Nitto Denko Technical Corporation come in at
number eight. In 1977 audiences were wowed by the special effects in that
cinematic classic, which included a hologram of Princess Leia making a
distress call to Obi-Wan Kenobi. Now, Peyghambarian and team have taken a
big step towards making such real-time, dynamic holograms a reality by
inventing a photorefractive polymer screen that reacts very quickly to laser
light.
9th place: Proton is smaller than we
thought<http://physicsworld.com/cws/article/news/43128>

Physicists have been making measurements of protons for more than 90 years
so you would have thought its size would be settled. But this year an
international team led by Randolf Pohl at the Max Planck Institute for
Quantum Optics discovered that the proton is about 4% smaller than
previously thought – bagging ninth place in our list. The surprising result
was obtained by studying "muonic" hydrogen in which the electron is replaced
by a much heavier muon. The finding could mean that physicists need to
rethink how they apply the theory of quantum electrodynamics (QED) – or even
that the theory itself needs a major overhaul.
10th place: CERN achieves landmark
collisions<http://physicsworld.com/cws/article/news/44276>
[image: Lead collisions, imaged by the ALICE
detector]<http://images.iop.org/objects/phw/news/14/12/18/break4.jpg>
Lead collisions <http://images.iop.org/objects/phw/news/14/12/18/break4.jpg>

We couldn't have a top 10 list that does not include the significant
breakthroughs in accelerator technology at CERN's Large Hadron Collider
(LHC). In March, LHC physicists achieved the first 7 TeV proton–proton
collisions <http://physicsworld.com/cws/article/news/42188> ever achieved in
a particle accelerator. And what's more, in November the LHC moved
seamlessly into the business of colliding lead
ions<http://physicsworld.com/cws/article/news/44276>in a successful
bid to recreate the conditions of just after the Big Bang.
Both runs generated copious amounts of data that will keep physicists busy
until the accelerator starts up again next year.

"

...

Henk Elegeert

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