MIT Group Studies Transfer of Bose-Einstein Condensates with Optical Tweezers

Conventional BEC production techniques severely limit optical and mechanical access to experiments due to the many laser beams and magnetic coils needed to create them. This conflict between cooling infrastructure and accessibility to manipulate and study condensates has been a major restriction to previous experiments. So far, most experiments were carried out within a few millimeters of where the condensate was created. What is highly desirable is a condensate "beam line" that delivers condensates to a variety of experimental platforms.

The Ketterle group at MIT has transported gaseous BECs over distances of up to 44 cm. This transfer was accomplished by trapping the condensate in the focus of an infrared laser and translating the location of the laser focus with controlled acceleration. Condensates of order 106 atoms were moved into an auxiliary "science" chamber that has excellent optical and mechanical access. This technique is ideally suited to deliver condensates close to surfaces, e.g., to microscopic waveguides and into electromagnetic cavities. As a proof-of-principle demonstration, they have used the tweezers technique to transfer condensates into a magnetic trap formed by a Z-shaped wire suspended in the science chamber. The same procedure can now be used to load condensates into atom chips. In such devices, patterns of wires are lithographically deposited on a surface and may allow the realization of single-mode waveguides and atom interferometers.

A report describing this work is available in the article "Transport of Bose-Einstein Condensates with Optical Tweezers" by T.L. Gustavson, A.P. Chikkatur, A.E. Leanhardt, A. Gšrlitz, S. Gupta, D.E. Pritchard, and W. Ketterle, in Phys. Rev. Lett. 88, 020401 (2002).