Quantum mechanics has taught us that atoms behave like waves, spreading out in space and being able to interfere much like light waves do. The tiny size of these matter waves and their fast and irregular movement play together to hide them from even a microscope's view under normal conditions. This changed dramatically when the first atom lasers were built a few years ago. By realizing a phenomenon known as Bose-Einstein condensation, physicists were able to put thousands of atoms into the same quantum state, and to take real-life images of this amplified atomic matter wave with an ordinary video camera.
Many scientists believe that Bose-Einstein condensates and atom lasers will lead to revolutionary new technologies, just as laser has revolutionized fields as diverse as eye surgery, consumer audio electronics and high-speed telecommunication. However, much like the early lasers, the first atom lasers were bulky machines that filled entire research laboratories. Indeed, to suspend (trap) the cloud of atoms, they used large, water-cooled electromagnets that consumed as much electrical power as a few dozen hair dryers. Moreover, the most advanced vacuum technologies were needed to isolate the atoms from their environment while they were being cooled down to the near-absolute zero temperature which is required for Bose-Einstein condensation.
Now, Wolfgang Hänsel, Peter Hommelhoff, Theodor W. Hänsch, and Jakob Reichel of the Max Planck Institute for Quantum Optics and the University of Munich have dramatically simplified atom laser construction by using a thumbnail-sized microchip to achieve Bose-Einstein condensation (Nature, Oct. 4, 2001). In their experiments, the cloud of condensed atoms hovers just above the micron-sized gold wires which are inscribed on the chip. The microchip not only replaces the coils and cuts the power consumption to a small fraction of what it used to be. In addition, it drastically shortens the time required to produce the condensate, from about minute to a few seconds. This in turn relaxes the stringent vacuum requirements of the older experiments.
But the new technique has another advantage, which may well turn out to be the most important one. Just as in microelectronics, many atom-optical components may be integrated on a single chip. In their first experiments, the Munich researchers successfully transported the fragile matter waves along the chip surface, using a special arrangement of microwires to create a magnetic conveyor belt. Hänsel and colleagues believe that this demonstrates the versatility of the new method, which could become a standard tool in future devices which employ Bose-Einstein condensates. As a next step, the team proposes an integrated atom interferometer, which could be used as an ultra-sensitive magnetic field probe. Other devices will follow.
Dr. Jakob Reichel
Max Planck Institute for Quantum Optics
Phone: 49 89 21 80 39 39 or 39 37
Fax: 49 89 28 51 92
Email: [email protected].