Meissner effect in superconducting microtraps

TL;DR

This paper demonstrates a superconducting microtrap for ultra cold atoms near Nb wire, revealing how the Meissner effect influences magnetic trapping and field exclusion at different temperatures.

Contribution

It provides the first detailed experimental characterization of the Meissner effect's impact on magnetic microtraps for ultra cold atoms near superconducting wires.

Findings

Complete magnetic field exclusion below 6K

Trap position shifts with temperature due to partial field penetration

Meissner effect alters trap parameters near superconductors

Abstract

We report on the realization and characterization of a magnetic microtrap for ultra cold atoms near a straight superconducting Nb wire with circular cross section. The trapped atoms are used to probe the magnetic field outside the superconducting wire. The Meissner effect shortens the distance between the trap and the wire, reduces the radial magnetic-field gradients and lowers the trap depth. Measurements of the trap position reveal a complete exclusion of the magnetic field from the superconducting wire for temperatures lower than 6K. As the temperature is further increased, the magnetic field partially penetrates the superconducting wire; hence the microtrap position is shifted towards the position expected for a normal-conducting wire.