Strongly Enhanced Sensitivity EPR through Bimodal Resonators and Quantum-Limited Amplifiers

Electron paramagnetic resonance (EPR) is a powerful tool employed across various disciplines including structural biology, chemistry, physics, material science, and many others.

It provides important and unique information on a local electron spin environment, electronic properties and dynamics of various paramagnetic centers. However, a relatively low sensitivity of this method often limits the range and type of systems that can be studied.

Thus, major advancements in EPR sensitivity are crucial to significantly broaden its applicability, encompassing new and highly relevant systems such as single cells.The Strongly Enhanced Sensitivity EPR through Bimodal Resonators and Quantum-Limited Amplifiers (Strong-ESPRESSO) project will ignite a revolution in EPR by employing sophisticated bimodal microwave resonators and intricate ways of noise reduction in tandem with novel microwave amplifiers developed for quantum technologies.

We will achieve this by first delivering a new generation of EPR cryoprobeheads, which will utilize the orthogonal-field bimodal cavities, allowing to reach the sensitivity limit of these instruments.

Secondly, we will transfer the bimodal cavity concept to planar superconducting microresonators, enabling the employment of these tools to study tiny (pL volume) samples of typical fast-decohering spin systems (e.g. protein droplets).

Finally, we will develop an ultra-sensitive EPR setup based on the radiative cooling effect of the bimodal resonators and recent advances in the quantum-limited microwave amplifiers.

This revolutionary new setup is expected to provide a ground-breaking 5000x reduction in the EPR measurement time, simultaneously preserving compatibility with ordinary EPR experiments and samples.

Throughout the project, we will immediately apply the developed tools to study new and intricate spin systems in the fields of catalysis, protein droplets, and single cells, leading to major impacts far beyond EPR.