Direct visualization of quasiparticle concentration around superconducting vortices
Jian Feng Ge (Universiteit Leiden, Max Planck Institute for Chemical Physics of Solids)
Koen M. Bastiaans (Universiteit Leiden, TU Delft - QN/Otte Lab, Kavli institute of nanoscience Delft)
Jiasen Niu (Ludwig Maximilians University, Universiteit Leiden)
Tjerk Benschop (Universiteit Leiden)
Maialen Ortego Larrazabal (Universiteit Utrecht)
Milan P. Allan (Ludwig Maximilians University, Universiteit Leiden)
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Abstract
Bogoliubov quasiparticles play a crucial role in understanding the behavior of a superconductor and in achieving reliable operations of superconducting quantum circuits. Diagnosis of quasiparticle poisoning at the nanoscale provides invaluable benefits in designing superconducting qubits. Here, we use scanning tunneling noise microscopy to locally quantify quasiparticles by measuring the effective charge. Using the vortex lattice as a model system, we directly visualize the spatial variation of the quasiparticle concentration around superconducting vortices, which can be described within the Ginzburg-Landau framework. This shows a direct, noninvasive approach for the atomic-scale detection of relative quasiparticle concentration as small as 10−4 in various superconducting qubit systems. Our results alert of a quick increase in quasiparticle concentration with decreasing intervortex distance in vortex-based Majorana qubits.
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