Dr. Lene Hau is a leading physicist in the field of Bose-Einstein Condensates, specializing in research that explores the usage of BECs to slow down and manipulate light. Using a laser induced quantum interference in a BEC, Dr. Hau and her team were able to slow down, and eventually completely stop a light pulse inside a sodium Bose-Einstein Condensate. Using this technology and techniques, Dr. Hau and her team were able to create a pair of BECs that allowed them to stop and extinguish a light pulse in one of them, and revive that same light pulse in the other.

The method Dr. Hau used to create this phenomenon is exactly as it sounds. They first sent a light pulse from a laser into the first condensate. When this light pulse is in the condensate, it is slowed down and its length is spatially compressed to be shorter than the BEC. Then, the coupling field is turned off in the system. When this happens, the atoms in the light pulse go into a quantum superposition state consisting of a stationary component and a recoiling component.

This recoiling part of the wavefunction acts as a “messenger pulse” and carries the information, including the amplitude and phase, of the stationary light pulse towards the second Bose-Einstein Condensate. When this messenger pulse is fully inside the second condensate, the coupling field is reactivated. When it is turned on, the messenger pulse particles exit quantum superposition and are added to the matter field of the second condensate, reviving the light pulse in the second BEC.

Dr. Hau and her team have discovered that this revived light pulse retains information about the messenger pulse, such as the distance between the two condensates. These messenger pulses can also be reused and repeatedly moved from one condensate to another. They could also be independently trapped and manipulated, with these changes being mapped on the revived light fields. They have theorized that this light manipulation technology using BECs could be used for the basis of a new-type interferometer to measure “off-diagonal long-range order in spatially selected regions of degenerate gases of fermions and bosons.” Dr. Hau has also theorized that the ability to control light pulses in such a way could be applied in quantum information processing and wavefunction sculpting.