Deutsch Contact Deutsch
QuantumFrontiers
 
QuantumFrontiers Sharing Science Public Outreach Stories

Success Story: Quantum- & nano-engineering of atom interferometers and clocks

© Jan Hosan/TUBS
Nano-structured meta-mirrors were developed with record-low losses, additionally benefiting gravitational wave detectors [1]

Quantum sensors based on ultracold atoms and ions are a paradigm of quantum technologies, where the quantum and many-body features of these systems can be used to approach the fundamental quantum limit. A collaboration among QuantumFrontiers researchers from experimental quantum optics, theoretical physics, and engineering at Leibniz University Hannover, the National Metrology Institut PTB and TU Braunschweig has led to remarkable advancements in measuring physical quantities, such as Earth’s acceleration with atom interferometers and frequency ratios between optical clocks.

World record in frequency comparisons

QuantumFrontiers improved the accuracy of frequency ratios between optical clocks to a fractional uncertainty level of 10–18 [2–4]. This involved performing precise atomic property measurements [5, 6] and employing quantum engineering techniques like twisted light interrogation schemes [7], dynamical decoupling [8], and entanglement [9–11]. The researchers pioneered the first multi-ion [2, 12] and transportable clocks, enabling faster averaging times and geodesy applications [13]. They have also established novel, globally unique systems with low systematic shifts and high sensitivity to new physics, such as highly-charged ions [14] and the thorium nucleus [15], opening new research fields. Building on the world-leading silicon cavity-stabilised lasers, QuantumFrontiers researchers have implemented single-crystal coatings with reduced thermal noise for high stability clocks and identified an unexpected birefringent noise source [16].

Illustration of the laser interrogation of a highly charged ion clock

Pushing the limits of atom interferometry

Matter wave interferometry with Bose Einstein Condensates (BEC), pursued by QuantumFrontiers researchers, offers superior control over spatial localisation and systematic shifts [17]. Key parameters to enhance atom interferometer resolution are long probe times and large enclosed areas. They developed ultra-cold sources enabling probe times on the order of seconds [18–20], achieved large momentum transfer beam splitters for large enclosed areas [21], and developed concepts to achieve systematics at the μrad resolution [22]. Surpassing single-particle physics, they devised a technique to generate entangled spin-squeezed states for atom interferometry using rapid trapping potential changes [23], mapped spin-squeezing to momentum states [24], culminating in the realisation of the first entanglement-enhanced atom gravimeter below the standard quantum limit [25].

This article is part of a series on QuantumFrontiers success stories

We identified atomic interactions as a sensitivity limit in squeezed state interferometers and devised tailored states to overcome this [26]. To further push the limits, these techniques will be implemented in the VLBAI facility with a 10 m baseline, which has recently been commissioned with rubidium atoms

Cold Atoms in Space

© NASA/JPL-Caltech
View from the International Space Station of the capsule that brought the Cold Atom Lab to the ISS.

For ultra-long probe times, space is the ultimate solution. QuantumFrontiers researchers demonstrated the first atom interferometry in space [27] and used the Cold Atom Lab on the ISS, demonstrating its functionality as a source for BEC interferometry [28]. Recently, the first dual-species BEC in space was demonstrated [29], paving the way for quantum tests of the universality of free fall with different species at long interferometry times. QuantumFrontiers principle investigators play key roles in missions like Cold Atom Rubidium Interferometer in Orbit for Quantum Accelerometry (CARIOQA) and the BECCAL, a multi-user facility on the ISS [30].

Topical Groups involved

Publications

Last Change: 25.09.24; Dr. A. Wanner Print

Contact us
Contact