A Matter-Wave Interferometer for Large Molecules

A matter-wave interferometer for large molecules has been devised and demonstrated for the first time.

For many years scientists have studied the proposition that things we normally think of as particles, such as electrons, should also have wave properties.

Indeed studies of beams of electrons, neutrons, even whole atoms, have confirmed that particles can be viewed as a series of traveling waves which diffracted when they pass through a grating or through slits. These waves could even interfere with each other, resulting in characteristic patterns captured by particle detectors.

In this way, in 1999 Anton Zeilinger and his colleagues at the University of Vienna demonstrated the wave nature of carbon-60 molecules by diffracting them (in their wave manifestation) from a grating (Update 453).

Now the same group, using a full interferometer consisting of three gratings with wider grating spacings and a more efficient detector setup, observe a sharp interference pattern.

Moreover, because the beam of particles used, carbon-70 molecules at a temperature of 900 K, are themselves in an excited state (undergoing 3 rotational and 204 vibrational modes of internal motion), it should be possible to study the way in which an atom wave, or in this case a macromolecular wave, becomes decoherent (that is, loses its wavelike character) because of thermal motions and other interactions with its environment. Thus this type of interferometer experiment will be useful in studying the borderland between the quantum and classical worlds.

The researchers (contact Bjorn Brezger, bjoern@brezger.de, University of Vienna) are aiming to study the wave properties of even larger composite objects, mid-sized proteins. (Brezger et al., Physical Review Letters, 11 March 2002; see also Professor Zeilinger's website.)