Fermi condensates for dynamic imaging of electro-magnetic fields

TL;DR

This paper proposes using Fermi condensates for non-invasive, high-resolution sensing of static and dynamic electromagnetic fields by exploiting the tunable energy gap in their excitation spectrum, enabling selective frequency detection.

Contribution

It introduces a novel method utilizing Fermi condensates' tunable energy gap for electromagnetic field sensing, expanding beyond existing Bose-Einstein condensate sensors.

Findings

Calculated the dynamic structure factor of the Fermi gas.

Analyzed the sensitivity and spatial resolution of the proposed sensing method.

Suggested potential for sub-micron spatial resolution with advanced quasiparticle detection techniques.

Abstract

Ultracold gases provide micrometer size atomic samples whose sensitivity to external fields may be exploited in sensor applications. Bose-Einstein condensates of atomic gases have been demonstrated to perform excellently as magnetic field sensors \cite{Wildermuth2005a} in atom chip \cite{Folman2002a,Fortagh2007a} experiments. As such, they offer a combination of resolution and sensitivity presently unattainable by other methods \cite{Wildermuth2006a}. Here we propose that condensates of Fermionic atoms can be used for non-invasive sensing of time-dependent and static magnetic and electric fields, by utilizing the tunable energy gap in the excitation spectrum as a frequency filter. Perturbations of the gas by the field create both collective excitations and quasiparticles. Excitation of quasiparticles requires the frequency of the perturbation to exceed the energy gap. Thus, by tuning the gap, the frequencies of the field may be selectively monitored from the amount of quasiparticles which is measurable for instance by RF-spectroscopy. We analyse the proposed method by calculating the density-density susceptibility, i.e. the dynamic structure factor, of the gas. We discuss the sensitivity and spatial resolution of the method which may, with advanced techniques for quasiparticle observation \cite{Schirotzek2008a}, be in the half a micron scale.