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Progress in atomic, optical and quantum science1, 2 has led to rapid improvements in atomic clocks. At the same time, atomic clock research has helped to advance the frontiers of science, affecting both fundamental and applied research. The ability to control quantum states of individual atoms and photons is central to quantum information science and precision measurement, and optical clocks based on single ions have achieved the lowest systematic uncertainty of any frequency standard3, 4, 5. Although many-atom lattice clocks have shown advantages in measurement precision over trapped-ion clocks6, 7, their accuracy has remained 16 times worse8, 9, 10. Here we demonstrate a many-atom system that achieves an accuracy of 6.4 × 10−18, which is not only better than a single-ion-based clock, but also reduces the required measurement time by two orders of magnitude. By systematically evaluating all known sources of uncertainty, including in situ monitoring of the blackbody radiation environment, we improve the accuracy of optical lattice clocks by a factor of 22. This single clock has simultaneously achieved the best known performance in the key characteristics necessary for consideration as a primary standard-stability and accuracy. More stable and accurate atomic clocks will benefit a wide range of fields, such as the realization and distribution of SI units11, the search for time variation of fundamental constants12, clock-based geodesy13 and other precision tests of the fundamental laws of nature. This work also connects to the development of quantum sensors and many-body quantum state engineering14 (such as spin squeezing) to advance measurement precision beyond the standard quantum limit.

Several recent papers on biomimetics and photonics, including works on structural colours, radiation shielding, spiders and more.

including one for Tom: Structural color and its interaction with other color-producing elements: perspectives from spiders Bor-Kai Hsiung ; Todd A. Blackledge ; Matthew D. Shawkey [+] Author Affiliations Proc. SPIE 9187, The Nature of Light: Light in Nature V, 91870B (September 8, 2014); doi:10.1117/12.2060831

Dirac cones, a band-structure of two cones touching each other, are the key to understand graphene exceptional properties. They also appear in the theory of photon waveguides and atoms in optical lattices. In here, the study of a Dirac cone deformation in an open system (a system that is perturbed by external agents) lead to the deformation of the Dirac cone, meaning a change in the fundamental properties of the system. This change is such that strange phenomena such as unidirectional transmission or reflection or lasers with single mode (really single) operation can be achieved. Proved experimentally in photonic crystals. New way for extremely pure lasers?

essentially they made an experiment that does not prove or disprove anything -big deal-... what is the scientific value of "strongly disfavour"??? I also like the sentence "most models do not have exact predictions for the energy scale associated with this violation of Lorentz invariance" ... but if this is true WHAT IS THE POINT OF THE EXPERIMENT!!!! God, physics is in trouble ....

hum, null result experiments are not useless !!! there is always the hope of finding "something wrong", which would lead to a great discovery. For the state of theoretical physics (the "no exact predictions" quote), i totally agree that physics is in trouble... That's what happen when physicists don't care anymore about experiments...! All you can do now is drawing "nice"graph with upper bounds on some parameters of an all tunable weird theory !

Carrier multiplication (CM) is a process in which absorption of a single photon produces not just one but multiple electron-hole pairs. This effect is a potential enabler of next-generation, high-efficiency photovoltaic and photocatalytic systems.

What would you do if you owned the world's most powerful laser? The US government is hoping to use it to achieve the ignition of thermonuclear fusion in the lab for the first time. Nature Photonics spoke to Edward Moses of the National Ignition Facility t

n some semiconducting nanocrystals one photon can release two or three electrons, hence the term avalanche effect. This could theoretically lead to a maximum output of 44 percent in a solar cell comprising the correct semiconducting nanocrystals.

Although it may seem like the above two experiments violate the uncertainty principle because the results show a smaller-than-required degree of uncertainty, Shih and his coauthors explain that no violation has occurred due to the fact that the experiments involve photon pairs rather than individual photons. The scientists argue that Popper's original thought experiment was based on a misunderstanding of the proper context of the uncertainty principle: it governs the behavior of single particles only, not the "correlation" of two particles.

'Whether mysterious high-energy photon emissions from our Galaxy come from dark matter or a more mundane source might be resolved by detecting their Doppler shifts along different lines-of-sight.'

An alternative to photon-beam driven sails?

One overview about a recent publication (10/06/2014 http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.112.236802) showing room temperature operation of a new type of laser 'discovered' in 2013, the polariton laser. This new type of laser shows extremely low threshold current density - 2 orders of magnitude below Vertical Cavity Surface Emitting Lasers (VCSEL) - and it is believed to become one important component of nanophotonic integrated components.

I think there are a few difficulties when assuming that the macroscopic block of glass will accelerate instantaneously. Also, if I prevent the block from moving would it become perfectly reflective as no momentum can be transferred to it? One could say that the momentum is then transferred to the larger system that holds the glass. But surely I could make that system (or even the block of glass) so heavy that it would not move more than Planck's length during the passage of the photon - especially if the glass is very thin or the light is very red.

Extremely charged Xe ions by stripping off more electrons than previously thought possible ...

Impressive ...

"You won't believe this one weird quantum mechanical trick Begonia uses!"

If I remember correctly there was a presentation at the ACT in 2014(?) about the quantum-mechanical effects essential to photosynthesis by an external speaker.