Physics Tip Sheet #9 - April 17, 2002
Contact: David Harris
American Physical Society
1) Identical twin photons
V. Giovannetti, L. Maccone, J. H. Shapiro, and F. N. C. Wong
Physical Review Letters (Print issue: May 6, 2002)
Maximally entangled photons are a prime resource for quantum teleportation, communication and cryptography. However, most techniques for entangling photons achieve only partial entanglement. A new experiment using the usual experimental equipment shows how to create photons that are maximally entangled and also identical in frequency. Previous experiments had photons that matched perfectly in time rather than frequency. Frequency matching can be used to make more precise position measurements and for better clock synchronization.
Journal article: http://link.aps.org/abstract/PRL/v88/e183602
2) The attosecond camera (Two papers)
J. Itatani, F. Quiri, G. L. Yudin, M. Yu. Ivanov, F. Krausz, and P. B. Corkum; and
M. Kitzler, N. Milosevic, A. Scrinzi, F. Krausz, and T. Brabec
Physical Review Letters (Print issue: April 29, 2002)
If physicists are able to probe shorter and shorter time scales, they will be able to observe the dynamics of electrons within atoms and other subatomic phenomena. Two proposals for an "attosecond streak camera" are able to resolve pulses of light with attosecond durations (10^-18 seconds or a billionth of a billionth of a second). X-ray photons that ionize atoms are used in these studies and the electrons that are ejected from the atoms are measured to gain information about the photons involved in the process. The authors claim the technique will allow a resolution better than 100 attoseconds.
3) Molecular conductivity takes shape
J. Reichert, R. Ochs, D. Beckmann, H. B. Weber, M. Mayor, and H. v. Lvhneysen
Physical Review Focus/Physical Review Letters (Print issue: April 29, 2002)
A German team have shown that an asymmetrically shaped molecule conducts electricity differently depending on which direction the current flows. The experiment marks a step toward controlling single-molecule conductivity by designing the molecule.
4) Ultrahigh energy neutrinos (Three papers)
Kusenko and Weiler; Feng, Fisher, Wilczek, and Yu; Fodor, Katz, and Ringwald
Physics News Update/Physical Review Letters (Prints issues: April 22/29, 2002)
Ultrahigh-energy neutrinos might be made in a variety of ways (in the warped space near black holes, say, or in the decay of exotic massive particles) and might be detected on Earth in a variety of ways. This issue is explored in three upcoming articles in Physical Review Letters.
Physics News Update: http://www.aip.org/enews/physnews/2002/split/585-2.html
Journal article: http://link.aps.org/abstract/PRL/v88/e161101
Journal article: http://link.aps.org/abstract/PRL/v88/e161102
Journal article: http://link.aps.org/abstract/PRL/v88/e171101
5) Infant respiratory disease
J. Ding, H. E. Warriner, and J. A. Zasadzinski
Physics News Update/Physical Review Letters (Print issue: April 22, 2002)
An in-vitro study of the surfactant lining infants' lungs shows that the balance of liquid to crystal components is vital in helping the lungs swap carbon dioxide from the blood for oxygen. Changing the surfactant composition can alter the fraction of crystals in the single-molecule layer, so it is possible to engineer it to have the required properties. These findings should help researchers formulate better replacement surfactants for treatment of premature infants with Respiratory Distress Syndrome (RDS).
Physics News Update: http://www.aip.org/enews/physnews/2002/split/584-1.html
Journal article: http://link.aps.org/abstract/PRL/v88/e168102
6) Multi-megagauss magnetic pulses
A. S. Sandhu, A. K. Dharmadhikari, P. P. Rajeev, G. R. Kumar, S. Sengupta, A. Das, P. K. Kaw
arXiv preprint server
An experiment has created magnetic fields about 27 million times stronger than the Earth's by using an intense laser beam on a target to create a "solid plasma". Understanding these high fields is vital for fast ignition schemes in laser fusion and hybrid plasma containment.
Papers from the Physical Review series of journals are available pre-publication to journalists on request.
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