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Research group - Non-Classical States of Matter

Two billion rubidium atoms (red, in the middle of the glas cell) captured in a magneto-optical trap with UV-light induced desorption. Photo: Oliver Topic

Since the time of Heisenberg’s uncertainty principle published in 1927, it has been known that physical observables cannot be measured with arbitrary precision. However, quantum mechanical states can nonetheless be engineered to possess observables with exceptionally small fluctuations—the so-called squeezed states. Squeezed, non-classical states of laser light have recently made the transition from a research topic to a tool for precision measurements. Similarly precision measurements using atoms instead of photons have improved dramatically over the past decades. Hence there is great interest in investigating possible routes towards the creation of such squeezed, states of atomic matter waves.

The members of this research group have investigated a new mechanism to create such non-classical states using the matter wave counterpart of the laser, the Bose-Einstein condensate (BEC). Atomic BECs consist of ultracold atoms in the gaseous phase, which all share exactly the same quantum state. The scientists created a BEC of Rubidium atoms, which can be oriented in a magnetic field analogously to small magnets. Starting with all atoms oriented horizontally, it has been shown that atomic pairs are created spontaneously with an up/ down orientation. This process is due to the amplification of the inherent vibrations of the vacuum, the so-called vacuum fluctuations.

At the moment, measurements are in progress to show that the produced up/ down atom pairs have squeezed observables. Finally, the new non-classical states of matter will be used to build a prototype interferometer that is able to benefit from the suppression of fluctuations.