NTT Research and Development 2008 Review of Activities

Quantum mechanics describes several counter intuitive phenomena such as that light behaves like both wave and particle and simultaneous measurement of the exact position and momentum of an object is not possible. If we could create quantum devices that could put such quantum phenomenon under our control, they would pave the way for the production of extraordinary products and services, e.g. ultra-high-speed quantum computers. Neutral atoms are promising candidates for producing quantum devices.

An important step to developing a quantum device is the precise control of the external motion of a single atom. However, normal conducting atom chips^*1 can not geometrically control a single atom because of their serious thermal noise problem. Recently, NTT Laboratories succeeded in producing a "persistent supercurrent atom chip", a device that can trap atoms with a practically noise-free magnetic field. Its ability can be observed in an experiment by looking at the silhouette of trapped atoms as illustrated in the figure.

The number of trapped atoms was about 0.5 million in the experiment. We will miniaturize the chip pattern to trap single atoms with a strong and stable magnetic field. Once we have highly sensitive measurement and precise control techniques for single atoms, we will develop quantum information devices. Besides its application to quantum information devices, the persistent supercurrent atom chip may also be a building block of single mode atoms interferometers^*2, with which a highly sensitive gravitation meter to search for underground resources could be created.

• *1 atom chip: A device that can trap atoms in a magnetic potential generated by a current driving through a wire on the surface.
• *2 atom interferometer: An instrument in which matter wave interference is employed to make precise measurements. It is expected to be ten billions times as sensitive as a similar scale light wave interferometer.