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A crystal made of several hundred ions — its fluorescence signal is shown at the centre of the cover image — has been coupled strongly to the modes of an optical cavity. Cavity QED with ion crystals offers a fresh approach to creating efficient light–matter interfaces and quantum memories, and potentially to cavity optomechanics. Letter p494; News & Views p455 Cover design by David Shand
Fraud in science is difficult to spot immediately, but, as high-profile cases show, it does get found out. Tackling plagiarism is at least becoming an easier fight.
Strong coupling of light and matter is the most important, yet challenging goal in the field of cavity quantum electrodynamics. This regime has now been reached by collectively exciting large crystals of trapped ions.
Optomechanics is a promising route towards the observation of quantum effects in relatively large structures. Three papers, each discussing a different implementation, now combine optical sideband and cryogenic cooling to refrigerate mechanical resonators to fewer than 60 phonons.
In YbRh2Si2, the transitions to a heavy Fermi-liquid state and to a magnetic phase occur at a single quantum critical point. But under chemical pressure, these transitions separate, and a new phase of matter appears in between.
Femtosecond laser pulses can demagnetize ferromagnetic metallic thin films on an ultrafast timescale. Studying how magnetic films react during optical excitation provides a better understanding of this so-called femtomagnetism.
Massive spectroscopic and imaging surveys of individual stars in the Milky Way are opening windows on the formation of the first elements and the nature of the assembly of the Galaxy.
Under chemical pressure, two phase transitions that were seemingly linked become detached in YbRh2Si2, thereby clarifying a long-standing mystery in the heavy-electron metals. Moreover, a new quantum phase appears under negative pressure.
An experiment demonstrates that single surface plasmons—collective electronic excitations on metal surfaces—show wave–particle duality. The result suggests that a macroscopic number of electrons can behave like a single quantum particle.
Plasmonics is heralded as the perfect symbiosis of optics, which is quick, and electronics, which works on a small scale. A method for electrically detecting plasmon polaritons using a quantum dot removes the need for far-field optical techniques and could enable nanoscale integrated circuits.
An approach that combines fluorescence and cavity-QED methods enables the fast and reliable detection of single atoms, and should be useful for a series of atomic-physics and quantum-information protocols.
Cooling optomechanical resonators to their quantum-mechanical ground state could enable the observation of quantum effects in macroscopic objects. The experimental cooling of a 43-ng silicon-nitride beam to a thermal occupancy of just 30 indicates that this ultimate goal is not too far away.
Combing cryogenic and so-called sideband cooling promises to cool micrometre-scaled resonators to the point at which quantum effects take hold. Hope that this aim will soon be reached is boosted by the demonstration of a deformed silica microsphere that is cooled so that it contains only 37 phonons.
The experimental realization of strong coupling between a Coulomb crystal—made of several hundred ions—and the light field in an optical cavity could provide a route to efficient light–matter interfaces.
Conventional understanding of the magneto-optical Kerr effect, in which changes in the magnetization of a material cause changes in the polarization of reflected light, assumes that this incident light is continuous. However, first-principles simulations of nickel show that this assumption breaks down for femtosecond pulses of light, and establishes a firm foundation for understanding the dynamics of femtomagnetism.
Measurements of the distribution of stochastic switching currents in homogeneous, ultra-narrow superconducting nanowires provide strong evidence that the low-temperature current-switching in such systems occurs through quantum phase slips—topological quantum fluctuations of the superconducting order parameter via which tunnelling occurs between current-carrying states.
Optomechanical systems in which a high-quality optical resonator is coupled to a mechanical oscillator hold great promise for examining quantum effects in relatively large structures. As a step towards this, a silica microtoroid has now been cooled to the point that it has just 63 thermal quanta.
Femtosecond laser pulses can demagnetize ferromagnetic metallic thin films on an ultrafast timescale. Studying how a single optical pulse interacts with a magnetic film now provides a better understanding of this so-called femtomagnetism.
Magnetic reconnection—the process by which magnetic field-lines break and reform in a plasma—is believed to be an important part of many astrophysical phenomena, but is poorly understood. The recreation of 3D reconnection events in a laboratory plasma provides a powerful means of studying the parameters that govern the onset, evolution and decay of this process.