A National Institute of Standards and Technology (NIST) scientist has demonstrated efficient production of single photons---the smallest pulses of light---at the highest temperatures reported for the photon source used. The advance is a step toward practical, ultrasecure quantum communications, as well as useful for certain types of metrology. The results are reported in the Feb. 23 issue of Applied Physics Letters.
"Single photon turnstiles" are being hotly pursued for quantum communications and cryptography, which involve using streams of individual photons in different quantum states to transmit encoded information. Due to the peculiarities of quantum mechanics, such transmissions could not be intercepted without being altered, thus ensuring that eavesdropping would be detected.
The photon source used in the NIST study was a "quantum dot," 10 to 20 nanometers wide, made of semiconductor materials. Quantum dots have special electronic properties that, when excited, cause the emission of light at a single wavelength that depends on dot size. An infrared laser tuned to a particular wavelength and intensity was used to excite the quantum dot, which produced photons one by one more than 91 percent of the time at temperatures close to absolute zero (5 K or about minus 459 degrees F) and continued to work at 53 percent efficiency at 120 K (minus 243 degrees F). Higher operating temperatures are preferable from a cost standpoint, because the need for cooling is reduced.
Laura Ost | EurekAlert!
Heating quantum matter: A novel view on topology
22.08.2017 | Université libre de Bruxelles
Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
22.08.2017 | Health and Medicine
22.08.2017 | Materials Sciences
22.08.2017 | Life Sciences