Volume 8 Issue 3, March 2012

A single photon can alter the shape of a molecule. It is now shown that quantum effects can play an important role in this change leading to conformation relaxation rates hundreds of times faster than previously expected.

Brillouin scattering of light is now shown to attenuate the Brownian motion of microscopic acoustic resonators. This electrostrictive phenomenon could be a useful complement to the ponderomotive and photothermal effects that can optically control optomechanical systems.

Geomagnetic storms driven by the solar wind can cause the flux of high-energy electrons in the Earth's Van Allen belts to rapidly fall. Analysis of data obtained during one such event from multiple spacecraft located at different altitudes in the magnetosphere reveals just where these electrons go.

A macroscopic quantum pendulum has now been created by confining a polariton condensate in a parabolic optical trap. Spectacular images of multiparticle wavefunctions are obtained by purely optical means.

According to Heisenberg, the more precisely, say, the position of a particle is measured, the less precisely we can determine its momentum. The uncertainty principle in its original form ignores, however, the unavoidable effect of recoil in the measuring device. An experimental test now validates an alternative relation, and the uncertainty principle in its original formulation is broken.

Polaritons—quasiparticles made up of a photon and exciton strongly coupled together—can form macroscopic quantum states even at room temperature. Now these so-called condensates are imaged directly. This achievement could aid the development of semiconductor-based polariton-condensate devices.

Measurements of Hanbury Brown and Twiss correlations in atomic gases near the Bose–Einstein condensation threshold reveal strong signatures of interactions between the constituent atoms, and establish such correlation measurements as a sensitive probe for the quantum properties of matter-wave sources.

The presence, or otherwise, of magnetism in graphene has been the subject of much debate. A systematic study of point defects—a widely suggested source of ferromagnetism in graphene—suggests that although they can exhibit net spin, they remain paramagnetic, even at liquid helium temperature.

A novel mechanism for cooling tiny mechanical resonators is now demonstrated. Inelastic scattering of light from phonons in an electrostrictive material attenuates the Brownian motion of the mechanical mode.

Geomagnetic storms driven by the solar wind can cause a dramatic drop in the flux of high-energy electrons in the Earth’s outer Van Allen belt. Analysis of data obtained during such an event by three different sets of spacecraft suggests that these electrons are directed into space rather than lost to the atmosphere.

The transport measurements of an interacting fermionic quantum gas in an optical lattice provide a direct experimental realization of the Hubbard model—one of the central models for interacting electrons in solids—and give insights into the transport properties of many-body phases in condensed-matter physics.

Superfluorescence—the emission of coherent light from an initially incoherent collection of excited dipoles—is now identified in a semiconductor. Laser-excited electron–hole pairs spontaneously polarize and then abruptly decay to produce intense pulses of light.

A molecule can alter shape as it absorbs a photon. It is now shown that quantum effects can play an important role in this change leading to conformation rates hundreds of times faster than previously expected.

Probing the explosion of nitrous oxide ions in real time using high-harmonic radiation and infrared laser pulses now provides insight into the correlated dynamics of electrons and nuclei during photoionization.

Individual molecules are now deterministically trapped in few-femtosecond laser pulses. This molecular conveyer belt may become a useful tool for probing ultrafast molecular dynamics.

Rapid particle acceleration is possible using a fixed-field alternating-gradient machine—but ‘scaling’ in its design has been necessary to avoid beam blow-up and loss. The demonstration now of acceleration in such a machine without scaling has positive implications for future particle accelerators.