Sep 25 2008
The European Science Foundation's new EUROCORES (European Collaborative Research Scheme) programme EuroQUASAR - European Quantum Standards and Metrology - could lead to crucial developments in time-keeping and scientific measurement.
The work may allow scientists to measure the effects of gravitational waves to go beyond Einstein's theories and gain new insights into quantum effects that will lead to quantum computers and communications. The programme will also pave the way for the most accurate optical clocks and inertial sensors ever made that will provide researchers with better than pinpoint accuracy in determinations of the fundamental physical constants of nature.
EuroQUASAR will build on European expertise in this field to develop the next generation of quantum standards that will form a new platform for exploiting quantum metrology and the novel techniques emerging from quantum engineering. Here, we highlight an exemplar project and hint at the potential of two more.
MIME
Professor Markus Arndt of the University of Vienna is project leader for one of the three EuroQUASAR Collaborative Research Projects (CRPs): "Molecule Interferometry and Metrology (MIME)". He and his colleagues in the international team are focusing on the development of new methods for quantum interferometry.
"The research is primarily driven by the desire to better understand the foundations of quantum physics and the transition between the "weirdness" of quantum physics and the "normality'" of our classical, everyday world," Arndt explains. MIME will open a window on waves made of matter and explore new applications that can investigate the properties of matter and answer questions about the interface between quantum physics and physical chemistry.
"This task requires the contribution of experts from complementary scientific disciplines," Arndt explains. MIME unites quantum experimentalists, (with Arndt coordinating the network from Vienna and colleague Hendrick Ulbricht moving to Southampton University, UK), quantum theorists (Klaus Hornberger, University of Munich, Germany), chemists (Marcel Mayor, University of Basel, Switzerland) and experts in nanotechnology (Herbert Gleiter and Horst Hahn, Karlsruhe, Germany).
"EUROCORES programmes help foster European collaboration by providing funding and an intellectual framework", explains Arndt, and shortly after the launch of the EuroQUASAR programme the MIME team announced its first scientific and fully collaborative success. The research was featured on the cover page of the prestigious chemistry journal Angewandte Chemie (Angew. Chem. Int. Ed. 2008, 47, 6195-6198).
Arndt and colleagues recently reported work that simultaneously advances both project goals at the same time. They have studied a large industrial catalyst molecule containing palladium metal and chemical groups packed with fluorine atoms. This compound is not amenable to the analyst's usual tool of choice, mass spectrometry (MS). MS is a powerful tool for probing particle mass but it usually relies on the use of charged particles. However, for many complex materials with weak bonds the ionisation process itself may modify the molecular composition, structure or conformation before it even reaches the detector. Instead, the team turned to matter wave interferometry to demonstrate their analytical prowess on the biggest molecule to show matter wave interference. The technique works because charge on a molecular can be skewed across the structure. This "polarisation" is a good indicator of molecular details, such as mass, geometrical or the sequence conformation.
Polarisability can be measured precisely using a Kapitza–Dirac–Talbot–Lau matter wave interferometer, as designed and build for the first time in Vienna. The test compound has a known mass of 3378.5 atomic mass units (amu), but earlier molecular beam experiments claimed just 1601 amu. This value corresponds to the mass of the two individual fluorine-containing building blocks. Since quantum interferometry depends on both the molecular mass and also its polarisability the team could discern molecular modifications in the source, in front of the interferometer, from those in the detector behind it. From the ratio of molecular polarisability and mass the MIME team then assigned the components in the molecular beam.
"The success of the experiment represents a good illustration of how new methods in basic science might also lead to new and initially unexpected solutions in applied research: the quantum interferometer can also assist as a complementary tool for mass spectroscopy (MS) and molecular analysis," Arndt explains. "It is important to develop methods that can identify and characterize neutral molecules," explains Arndt, "quantum interferometry is one such possibility."
"Future work will aim at extending the range of experiments to a larger variety of even more complex molecules and will address a wide range of molecular properties," Arndt adds. For instance, the researchers hope to work with molecules up to 10000 amu, which will be an order of magnitude bigger in mass and complexity than any other studied in quantum interferometry.
Two other Collaborative Research Projects include IQS and QuDeGPM
The main aims of IQS - Inertial Atomic and Photonic Quantum sensors: Ultimate Performance and Application - are to improve optical clocks using neutral atoms and single ions and to develop new scientific tools, such as novel cooling schemes, to improve optical clock performance.
Ultimately, the research being undertaken by Wolfgang Ertmer of the University of Hannover, Germany, and his colleagues may lead to a portable optical clock.
Within this consortium, the collaborative research team will investigate the ultimate potential of inertial atomic and photonic quantum standards and their applications in earth observation and fundamental physics. They suggest that for the first time scientists will be able to work together on atomic and photonic quantum sensors with experts in earth observation to measure gravity with unprecedented accuracy. The work will allow them to extend geophysical models and monitor fluctuations in the Earth's rotation.
The QuDeGPM - Quantum-Degenerate Gases for Precision Measurements - collaborative project will investigate the techniques of laser cooling and trapping that are used to create bright sources of macroscopic matter waves for use in atom interference experiments. The extension of this pioneering work will be carried out by Hanns-Christoph Nägerl, of the University of Innsbruck, Austria and colleagues, which will then be used in the precision determination of fundamental constants and inertial forces in free space, as well as highly sensitive measurements of surface forces on the micrometre-length scale.
Because atoms interact with each other, unlike photons of light, the researchers will be able to exploit various tricks from non-linear optics like squeezing to boost sensitivity. However, this interaction also represents a disadvantage in shifting phases of matter which have to be overcome using recent advances in controlling atomic interactions.
The project's main objectives are to perform precision atom interferometry with quantum degenerate gases, to use quantum degenerate gases for precision surface probing, and to develop novel test measurement schemes using non-classical matter wave states.