Single Impurity In Ultracold Fermi Superfluids

Abstract

The role of impurities as experimental probes in the detection of quantum material properties is well appreciated. Here we study the effect of a single classical magnetic impurity in trapped ultracold Fermi superfluids. Depending on its shape and strength, a magnetic impurity can induce single or multiple mid-gap bound states in a superfluid Fermi gas. The multiple mid-gap states could coincide with the development of a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase within the superfluid. As an analog of the Scanning Tunneling Microscope, we propose a modified RF spectroscopic method to measure the local density of states which can be employed to detect these states and other quantum phases of cold atoms. A key result of our self consistent Bogoliubov-de Gennes calculations is that a magnetic impurity can controllably induce an FFLO state at currently accessible experimental parameters.

5 pages, 3 figures; added calculations for 3D

References in corpus (10)

• Scanning tunneling spectroscopy of high-temperature superconductors
• Observation of the Pairing Gap in a Strongly Interacting Fermi Gas
• Phase diagram of a strongly interacting polarized Fermi gas in one dimension
• Anderson localization in Bose-Einstein condensates
• Tomographic RF Spectroscopy of a Trapped Fermi Gas at Unitarity
• Mean field thermodynamics of a spin-polarized spherically trapped Fermi gas at unitarity
• Bound states of a localized magnetic impurity in a superfluid of paired ultracold fermions
• Chandrasekhar-Clogston limit and phase separation in Fermi mixtures at Unitarity
• Self-localization of a small number of Bose particles in a superfluid Fermi system
• Oscillatory pairing of fermions in spin-split traps