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Three-axis Helmholtz coil system and a magnetic resonance detector in a shielded room for measuring magnetic flux density

Just how strong a magnetic flux density is can be determined with high precision by using magnetometers that are based on the principle of measuring nuclear magnetic resonance. PTB’s new method is particularly well suited for low fields within magnetic shields. This method uses hyperpolarized samples and drives at least two Rabi cycles – each one with different excitation frequencies. The new process makes it possible to determine magnetic fields more quickly than by using one individual free precession measurement that would take much longer. What is more, this new method is similarly accurate, and it can be used almost without destroying the hyperpolarization condition. (Technology Offer 548)

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The superconducting layer of a trap electrode (left) allows the photon detection of an ion that is trapped in a trap potential.

A quantum computer uses qubits to perform its operations. To date, ion traps have proved to be one of the best ways of manufacturing, storing and manipulating qubits. The concept developed by PTB is based on integrating components that have been separate until now. These are the sensor for photon detection and the trap electrode, which is made of a superconducting layer. The two components have now been combined. When a photon is absorbed, the superconductor changes from the superconducting state into the normal-conducting state. This change of state can be detected by measuring the resistance. PTB’s new approach allows a simplified architecture of ion traps, which is of particular importance when it comes to mass production. (Technology Offer 545)

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The calibration principle is impressively easy: The microphone to be tested is mounted on this disc. It rotates vertically and therefore exposes the microphone to a sinusoidal change of altitude. The velocity of the disc determines the pitch.

There is currently no reliable infrastructure for traceable calibration of measurement devices and sensors for measuring infrasound. As an important development step to improve this situation, a novel primary measuring setup for infrasound was set up at PTB. This new setup uses the decrease of ambient air pressure with increasing altitude as an excitation signal.

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Combining PTB’s digital calibration certificate (DCC) with DAkkS’s accreditation symbol contributes to widely automating production processes.

Following a successful pilot phase, accredited calibration laboratories will be able to apply for the digital calibration symbol starting in late March 2024 and thus provide digital proof that they are accredited. In combination with the digital calibration certificate developed by PTB, it serves as machine readable, tamper-proof and verifiable evidence of calibration which will ultimately replace paper calibration certificates.

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Simulation of electronic collision circuit: Two electron sources (S1, S2) simultaneously send indistinguishable electrons down counter-propagating paths. The electrons’ movement within the potential of an electronic beam splitter can be controlled precisely due to their mutual interaction. The outcome is detected by two detectors (D1, D2) that can determine the arrival of an individual electron.

Targeted collision of single photons or electrons enables a sensitive measurement method that can be used to investigate and control the way in which they influence each other. This reduction to single sharp signal impulses allows the measurement resolution to be improved and new components to be created for quantum information processing. In nanostructured semiconductor circuits, two separate electrons can be guided ballistically on intersecting signal paths; in this way, the electrons’ interaction can be used to control or probe electrical signals. The basic function of a non-linear circuit component of this type has been demonstrated in distinct, complementary realizations by three independent research teams led by NEEL (F), NPL (UK) and PTB.

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As part of the search for dark matter, three atomic clocks were compared, two of which use different transitions in the same Yb<sup>+</sup> ion stored in a single-ion trap (left). The third optical clock uses approx. 1000 neutral strontium ions in an optical lattice (right).

Can dark matter interact with photons and influence atomic structure? A comparison of two different kinds of optical atomic clocks at PTB has improved existing experimental detection limits for a possible coupling by more than an order of magnitude and over a wide range of dark matter particle mass. While no evidence of a dark matter coupling has been found, the work brings us closer to understanding the nature and potential interactions of dark matter.

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Schematic representation of the measuring room with a few sensors. By means of this new method, temperatures and their uncertainties can be estimated at any desired location based on local sensor data.

In principle, sensor networks and appropriate interpolation methods can be used to determine the temperature at any desired location in a room. The reliability of such interpolated data was tested at PTB.

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Brain pacemakers are very helpful for diseases such as Parkinson’s. But an implant can cause dangerous
tissue heating during an MRI scan. (X-ray image; source: Wikimedia Commons)

With well over 100 million examinations per year worldwide, magnetic resonance imaging (MRI) is the second most important medical imaging method. However, patients with implants often have to refrain from this life-saving diagnostic option or accept a lower image quality. Especially with active implants, such as cardiac pacemakers and neurostimulators, MRI scanning can lead to dangerous tissue heating in the body if not applied in a cautious way. PTB has shown that wireless communication between the implant and the magnetic resonance scanner can solve this problem.

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Vorhersage der globalen Erwärmung

Es ist der erste Check dieser Art: Auf der derzeit laufenden Weltklimakonferenz COP 28 in Dubai steht zum ersten Mal eine globale Bestandsaufnahme des Pariser Klimaabkommens auf der Tagesordnung. Es geht also um die Frage, ob das 1,5-Grad-Ziel aus der Pariser Klimakonferenz 2015 noch erreichbar ist – und wie es heute generell um das Weltklima steht. Um Fragen wie diese zu beantworten, ist eine große Zahl von Messwerten nötig, die laufend rund um die Welt erhoben werden: zu Lande, zu Wasser, in der Luft und sogar aus dem All. Dass diese Messwerte verlässlich, vergleichbar und genau sind, dafür sorgt eine ganz besondere Wissenschaft, die Metrologie. Bei der diesjährigen COP 28 sind Mitarbeitende des BIPM, des Internationalen Büros für Maß und Gewicht, mit einem Beobachterstatus als Vertretungen der nationalen Metrologieinstitute dabei. In Deutschland ist dieses Metrologieinstitut die Physikalisch-Technische Bundesanstalt (PTB). 

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