Trapping neutral atoms in the field of a vortex pinned by a superconducting nano-disc

Abstract

Atom chips made of superconducting material can generate magnetic traps with significantly reduced noise. Recently, several designs for superconducting chips have been theoretically analyzed and experimentally tested, for cases with many vortices considered as an average vortex density. Here we show theoretically, for the first time, how the magnetic field of a $single$ vortex, pinned by a superconducting nano-disc of radius $\sim$100 nm and combined with an external bias field parallel to the disc surface, yields a closed 3D trap for cold atoms. The size of the trap, and its height above the superconductor surface, are typically tens or hundreds of nanometers. We estimate the average lifetime $\tau$ of ${}^{87}$Rb (rubidium) atoms (subject to thermal escape and Majorana spin flips) in the range 0.05-1.0 ms. Next, we model the trap in a quantum adiabatic approximation and apply Fermi's rule to estimate the lifetime of ${}^{87}$Rb atoms in the ground state of this trap. We obtain similar lifetimes $\tau$ as in the semiclassical estimate, in the range 0.05-3.5 ms. We find that $\tau$ depends on the gradient $B_0$ of the vortex's magnetic field according to $\tau \sim (B_0{)}^{-2/3}$.

20 pages, 5 figures

References in corpus (7)

• Persistent Supercurrent Atom Chip
• Meissner effect in superconducting microtraps
• Spin flip lifetimes in superconducting atom chips: BCS versus Eliashberg theory
• Measurement of the trapping lifetime close to a cold metallic surface on a cryogenic atom-chip
• Impact of the Meissner effect on magnetic micro traps for neutral atoms near superconducting thin films
• Spontaneous Emission Near Superconducting Bodies
• Single vortex fluctuations in a superconducting chip as generating dephasing and spin flips in cold atom traps

Cited by in corpus (1)

• Sensitivity of ultracold atoms to quantized flux in a superconducting ring