Anwendungen in der Metrologie

© Quelle: Bodo Kremmin / LUH
Von den Grundlagen zur Anwendung

Der Forschungsbereich B „Anwendungen in der Metrologie" vereint sechs Forschungseinheiten, die das Anwendungsgebiet vom Nanobereich einzelner Moleküle bis zur wahrhaft makroskopischen Größe von Gravitationswellen-Detektoren abdecken.

Von den Grundlagen zur Anwendung

Der Forschungsbereich B „Anwendungen in der Metrologie" vereint sechs Forschungseinheiten, die das Anwendungsgebiet vom Nanobereich einzelner Moleküle bis zur wahrhaft makroskopischen Größe von Gravitationswellen-Detektoren abdecken.

Zu den metrologischen Anwendungen der Forschungsbereichs B gehören

  • die Subwellenlängen-Bildgebung,
  • Quantengravimeter,
  • Inertialsensoren,
  • optische Uhren und deren Vergleich über Glasfasernetze mit
  • Anwendungen von der Geodäsie und Umweltüberwachung bis hin zu neuen Tests der Fundamentalphysik.

Viele dieser Anwendungen werden erst durch den Fortschritt der Quanten-Nanoengineering-Technologie innerhalb des Forschungsbereichs A möglich, der kompakte, integrierte und transportable Sensoren und Messauflösung bei und über der jeweiligen Standard-Quantengrenze ermöglicht.


  • B1 “NanoLight”
    QUELLE: A.Waag



    Nanoscale optical light sources such as nano-LED arrays have been developed in the Epitaxy Competence Centre ec2at Braunschweig, a laboratory jointly operated with OSRAM OS GmbH giving QuantumFrontiers access to state-of-the-art LED technology. Nanoscale LED arrays enable structured-light applications below the optical diffraction limit. Microscopy without lenses has been realised, exploiting the large lateral coherence length of nanoscale LEDs, with a potential extension to optical 3D tomography. Within QuantumFrontiers this will allow the integration of optoelectronics with atom interference experiments, which is envisioned as the basis for future super-compact optical atom traps. Electromagnetic “super-resolution” in scanning THz-microscopy has been developed, based on superconducting quantum devices that combine ultrafast electronics and single flux quantum experiments. 

    Within QuantumFrontiers, quantised single electron transistors will be pursued, paving the way for cutting-edge low-noise current sources. These systems will be further developed to enable quantum-optics-like interference experiments with electrons, as well as novel quantum current standards. The atomically precise spatial nano-control of the injection of charge carriers into well-defined single quantum objects like single atoms or single molecules has been achieved by using the tunnel junction of a low-temperature scanning tunnelling microscope. This enables the possibility for injecting quantised current into quantum systems with the highest spatial resolution, with a potential extension towards robust single photon emitters.

  • B2 “Quantum Gravimetry and Inertial Sensing”

    In order to significantly advance gravimetry and to study quantum tests of the universality of free fall, QuantumFrontiers researchers have achieved a significant breakthrough in atom-interferometer performance by eliminating the several obstacles that prevented the employment of Bose-Einstein condensates (BEC) for interferometry. 

    The holy grail for further improving the sensitivity of atom interferometry was to extend the signal in space-time and achieve a BEC in free fall, although traditional atom-cooling methods are incompatible. To this end, QuantumFrontiers researchers have even achieved a BEC atom laser in microgravity conditions as demonstrated in a free-fall experiment at the drop tower in Bremen. These initial studies will be complemented by the LUH/HITec Einstein-Elevator testing ground in the future.

    © Source: IQO
    Bose-Einstein-Kondensat im Freien Fall (Quelle: IQO)
  • B3 “Optical Clock Networks”
    Strontium Atomwolke bei wenigen Millikelvin über dem absoluten Nullpunkt in der optischen Uhr der PTB (Quelle: C.Lisdat/PTB)

    QuantumFrontiers researchers play a key role in the development of the next generation of optical clocks for relativistic geodesy. Theirsingle ytterbium ion and strontium lattice clocks represent the frontier for Europe's most accurate devices and are in the first league internationally. In cooperation with several external groups, fibre-optical links were installed between Hannover, Braunschweig, Munich, Paris and London to disseminate optical frequencies over long distances. As a result, optical clocks can now be compared and characterised over long distances without loss of precision.

    This whole field, initiated by QuantumFrontiers researchers, will rapidly expand by adding more long-distance connections, e.g. to INRIM in Italy, and further international standard labs. Within QuantumFrontiers, we will develop multi-ensemble clocks and novel approaches for stable frequency references, employ non-classical states and quantum non-demolition readout schemes to perform fast clock comparisons at the 10-18 level and below. Furthermore, we will bring transportable optical clocks to a new level of integration and reliability for widespread use in geodesy.

  • B4 “Relativistic Geodesy”

    The aim of QuantumFrontiers is to explore new frontiers and techniques for the determination of the Earth’s gravitational field its temporal variations by monitoring the global and regional mass redistribution. Understanding the processes relevant for these changes such as the melting of the polar ice sheets, the contribution of water influx to sea level rise, and changes in the hydrological cycle allows the scientific community to better quantify and conceive climate change.

    Das Geoid der Erde. Abbildung: ESA Das Geoid der Erde. Abbildung: ESA Das Geoid der Erde. Abbildung: ESA
    Das Geoid der Erde. Abbildung: ESA
  • B5 “Gravitational Wave Astronomy”
    © LIGO/T. Pyle
    LIGO/T. Pyle

    QuantumFrontiers researchers are world leaders in the development of laser interferometric readout systems for terrestrial and space-based gravitational wave detectors. Much of the theoretical work and technology development that made the Advanced LIGO observatories so much more sensitive, making the Nobel prize-winning first direct detection of gravitational waves possible, was performed by QuantumFrontiers researchers.

    The GEO600 detector, operated by QuantumFrontiers researchers, was the first and is still the only gravitational wave observatory using squeezed quantum states of light in routine operation to improve its sensitivity. It serves as a development centre and test bed for future generations of gravitational wave observatories. The successful demonstration of the improvement of the detector’s sensitivity led to plans for the installation of squeezed light sources in all advanced gravitational wave detectors. And our technologies are integral features of third generation observatory proposals such as the Einstein Telescope (ET) observatory designed by a European study-team co-led by QuantumFrontiers scientists. Within QuantumFrontiers, we will continue our role as a “think tank” and investigate the foundations of and develop the technology for the next generations of gravitational wave detectors with significantly enhanced range, possibly culminating in the ability to listen to the “Big Bang”. For this we will tackle all noise sources, from fundamental photon shot noise and backaction noise over thermal noise to technical noise sources by employing high-power fibre-based sources of squeezed light and novel backaction evading and quantum noise cancelling techniques, employ nanostructured mirrors and higher-order modes, and develop quantum-limited technical noise suppression devices.


  • B6 “Tests of fundamental physics”

    The QuantumFrontiers consortium comprises experts in general relativity and its test on macroscopic scales using Lunar Laser Rangingwhich succeeded inlimiting a possible temporal drift of the gravitational constantto a world record of Ġ/G~1 x 10-131/yr and verified the strong equivalence principle to η~3 x 10-4. Furthermore, QuantumFrontiers researchers have used their clocks to obtain the most stringent limits so far for a possible temporal variation of dimensionless fundamental constants, like the fine-structure constant and the electron-proton mass ratio, which are predicted to change their value e.g. through coupling to dark matter. Within QuantumFrontiers, we will improve optical clock performance and make sensitive systems available through quantum logic spectroscopy, to further reduce these limits by more than one order of magnitude and thus contribute to excluding dark matter candidates and to a test of CPT symmetry violation. Furthermore, we will perform classical and quantum tests of relativity by probing Newton’s axioms, performing improved local Lorentz-invariance, redshift and universality of free-fall tests, and by investigating possible fundamental sources of decoherence in strongly delocalised quantum objects. 

    © M.Mathey/HITec