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Cryogenic thermometry based on superconducting microwave resonators

Applicant Furci Hernan
Number 193361
Funding scheme Ambizione
Research institution Laboratoire de microsystèmes 1 EPFL - STI - IMT - LMIS1
Institution of higher education EPF Lausanne - EPFL
Main discipline Technical Physics
Start/End 01.03.2021 - 28.02.2025
Approved amount 898'088.00
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All Disciplines (3)

Technical Physics
Microelectronics. Optoelectronics
Electrical Engineering

Keywords (11)

superconductivity; coplanar waveguide; microtechnology; microwave resonator; temperature sensor; thermometer; cryogenics; radiofrequency resonator; nanotechnology; multiplexed thermometry; low temperature physics

Lay Summary (French)

Les mesures physiques dans les systèmes cryogéniques, notamment de la température, requierent un nombre élevé de pénétrations à travers les parois du cryostat. Ceci résulte du besoin de câbles pour alimenter et lire chaque capteur individuellement. Ainsi, l'instrumentation à grande échelle présente des inconvenances en termes de fiabilité, sécurité et gestion des charges thermiques. Des résonateurs par microondes supraconducteurs ont non seulement été développés pour des application dans le domaine de la radiofréquence, mais aussi comme des détecteurs de photons multiplexés, c.à.d. qui peuvent être alimentés et lus par dizaines sur une seule ligne électrique.
Lay summary

Le but de ce travail es de développer la technologie nécessaire pour fournir des systèmes thermométriques multiplexés pour des applications cryogéniques basés sur des résonateurs par microondes supraconducteurs. Ceci inclut le développement des capteurs individuels ainsi que le réseau d'excitation et lecture.

En exploitant des propriétés intrinsèques des matériaux supraconducteurs et le comportement électromagnétique des diverses géométries des capteurs, nous optimiserons les designs pour maximiser la sensibilité. Nous allons aussi explorer comment la nano-fabrication peut nous permettre d'augmenter la réponse à la température par une nano-ingénierie dédiée du matériau.

Comme résultat de ce travail nous espérons fournir une série d'alternatives pour des systèmes thermométriques multiplexés pour une variété d'applications dans le champs de la physique et ingénierie des basses températures.

Direct link to Lay Summary Last update: 26.01.2021

Lay Summary (English)

Measuring physical parameters in cryogenic enclosures, namely temperature, requires a great number of penetrations on the walls or flanges of the cryostat. This stems from the need for electrical wires to power and read each sensor individually. Large scale wiring presents inconveniences in terms of reliability and safety, as well as thermal heat load management. Superconducting microwave resonators have been developed not only for applications in radio frequency, but also as photon detectors that can be multiplexed, i.e. powered and read by tens in a single electrical line.
Lay summary
The objective of this work is to develop the necessary technology in order to provide alternative multiplexed thermometry systems for cryogenic applications based on superconducting microwave resonators. This will include the development of the individual thermometers and the deployment of a sensor network with excitation and readout system.

Exploiting intrinsic properties of superconducting materials and the electromagnetic behaviour of different sensor geometries, we will try to reach thermometer designs of maximum sensitivity. We will also explore how nano-fabrication can allow us to increase the temperature response by a more dedicated material nano-engineering.

As an outcome of this work we expect to provide a range of different alternatives of sensors and multiplexed thermometry systems for different applications in the field of low temperature physics and engineering.  
Direct link to Lay Summary Last update: 26.01.2021

Responsible applicant and co-applicants



The common practices applied in cryogenic large devices for thermometry below 90 K rely on individual cabling of thermometers in a 4-wire scheme with DC readout. Thus, a detailed thermometry system with large number of sensors implies the need of an even larger number of wires and potentially risky penetrations, and considerable feedthrough space. In practice, this penalizes the size of a realizable distributed cryogenic thermometry system. The proposal for this grant is to develop technology aiming at providing a cryogenic distributed thermometry platform that reduces significantly the number of wires / channels on feedthroughs required for a large number of thermometers. The proposed approach is the development of specific superconducting coplanar waveguide microwave resonators. Besides the advantages of relative ease of fabrication and customization, moderate cost, small size and sensitivity, the choice relies on the fact that they can be spectrally multiplexed, allowing simultaneous probing of many of them on a single input/output port and transmission line. The research will aim at demonstrating and enhancing the capabilities of a thermometry system based on superconducting microwave resonators. Electromagnetic designs of the devices will be explored and refined to match the desired operative properties and to enhance their response to temperature. Chosen designs will be manufactured in the EPFL’s Center of Micronanotechnology (CMi) cleanrooms using thin films of selected superconducting materials. The sensors will be tested in a microwave cryogenic setup to assess their performance at low temperature and measure their operational parameters and calibration curves. Efforts will also be directed at increasing the sensitivity of the thermometers by nano-structuring the thin film material. With a full understanding of their overall behaviour, dedicated microwave operation schemes will be elaborated in order to either make the readout easier or to reduce the cost and size of the readout equipment for general or particular applications.