quantum mechanics tagged posts

Hologram of a single photon: reconstructed from raw measurements (left) and theoretically predicted (right). Credit: Source: FUW

Until quite recently, creating a hologram of a single photon was believed to be impossible due to fundamental laws of physics. However, scientists at the Faculty of Physics, University of Warsaw, have successfully applied concepts of classical holography to the world of quantum phenomena. A new measurement technique has enabled them to register the first ever hologram of a single light particle, thereby shedding new light on the foundations of quantum mechanics. “We performed a relatively simple experiment to measure and view something incredibly difficult to observe: the shape of wavefronts of a single photon,” says Dr. Chrapkiewicz.

In standard photography, ind...

The NIST-4 watt balance has measured Planck’s constant to within 34 parts per billion, demonstrating that the high-tech scale is accurate enough to assist with 2018’s planned redefinition of the kilogram. Credit: J. L. Lee/NIST

A high-tech version of an old-fashioned balance scale at the National Institute of Standards and Technology (NIST) has just brought scientists a critical step closer toward a new and improved definition of the kg. The scale, NIST-4 watt balance, has conducted its first measurement of the Planck’s constant to within 34 parts per billion – demonstrating the scale is accurate enough to assist the international community with the redefinition of the kilogram, an event slated for 2018.

The redefinition-which is not intended to alter the value of the kilogram’s mass, but ...

Atoms (shown in green and blue) are held in a trap of laser light (red) in which they can move in one dimension only. The atoms can point either up (green) or down (blue), similar to a needle in a compass. When the atoms do not interact, they can move freely in the trap (top picture); they have no discernible order. When repulsive interactions between the atoms are strong (bottom picture), they arrange themselves in the trap, with each atom pointing in the opposite direction of its neighbour.

Physicists have used ultracold atoms to imitate the behavior of electrons in a solid. Researchers have devised a new way to study the phenomenon of magnetism...

Interference of complex molecules are pictured in the Kapitza-Dirac-Talbot-Lau interferometer. Credit: Copyright: Quantum Nanophysics group, University of Vienna; Image: Mathias Tomandl & Patrick Braun

Topical research experiments are often too expensive or too complex to be rebuilt and incorporated in teaching. How can one, nevertheless, make modern science accessible to the public? This challenge was tackled in the research group Quantum Nanophysics led by Markus Arndt at the University of Vienna. For the first time, 2 research laboratories were created as complete, photorealistic computer simulations allowing university and high-school students as well as the general public to virtually access unique instruments...