Generation of high winding-number superfluid circulation in Bose-Einstein condensates

TL;DR

This paper presents a method to generate high winding-number superfluid circulation in Bose-Einstein condensates by spiraling a laser beam, enabling controlled vortex creation and persistent superflow for quantum fluid research.

Contribution

The authors introduce a novel optical technique to deterministically produce multiply-quantized superfluid circulation in BECs, achieving high winding numbers and controlled vortex placement.

Findings

Achieved superflow with winding numbers up to 11

Superflow persisted for at least 4 seconds

Controlled vortex configurations via laser beam manipulation

Abstract

We experimentally and numerically demonstrate a method to deterministically generate multiply-quantized superfluid circulation about an obstacle in highly oblate Bose-Einstein condensates (BECs). Our method involves spiraling a blue-detuned laser beam, which acts as a repulsive optical potential, around and towards the center of the BEC. This optical potential serves first as a repulsive stirrer to initiate superflow within the BEC, and then as a pinning potential that transports the center of the superfluid circulation to the center of the condensate. By changing the rate at which the beam moves along the spiral trajectory, we selectively control the net circulation introduced into the BEC. We experimentally achieve pinned superflow with winding numbers as high as 11, which persists for at least 4 s. At the end of the spiral trajectory, with the pinning beam on at full power, the BEC has a toroidal geometry with a high winding-number persistent current. Alternatively, the beam power can be ramped off, allowing controlled placement of a cluster of singly-quantized vortices of the same circulation. This technique can serve as a building block in future experimental architectures to create on-demand vortex distributions and superfluid circulation in BECs.