News 2005-06-01

Interference in a double well on an atom chip

We have developed a novel and easily implementable scheme for a phase preserving matter wave beam splitter, demonstrating for the first time coherent spatial splitting of matter waves on an atom chip. The splitting of a single well into a double well is based on a combination of static and radio frequency (RF) magnetic fields forming adiabatic potentials. By slowly changing the parameters of the RF current we smoothly change the adiabatic potentials and transform a tight 1-d magnetic trap into a double well consisting of two pallel 1-d traps, and thereby dynamically split a BEC.

(a) Schematic view of setup and (b) double well potential

We complete the interferometer sequence and measure the relative phase between the split BECs by recombining the clouds in time-of-flight expansion. In our experiments we find an interference pattern with a fixed phase as long as the two wells are not completely separated. The phase distribution remains non-random and its centre starts to evolve deterministically once the wells are entirely separated so that tunnelling is fully inhibited on all experimental time scales.

(a) Interference pattern and (b) Phase distribution

see also:

T. Schumm et al. [Nature Physics]
I. Lesanovsky et al. [physics/05100076]

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