Trapped Ion Gyroscope

Imagine you have been tasked with proving to a skeptic that sun does not orbit the Earth, but rather that the Earth is spinning about its axis.  No amount of referencing books or papers will convince this person -- they must see it with their own eyes.  How can it be done?

Well, if the Earth is spinning, we are spinning along with it and there sould be some effects of this motion.  And indeed there are, but none seem to be quite as compelling as the precession of a Foucault pandulum.  A pendulum, carefully set into motion at any lattitude other than the equator, will gradually change its plane of rotation as viewed by an observer rotating with the spinning Earth.  Such a device is known as a gyroscope -- a sensor for rotation.  Consider an arrow that always points the same direction in space (say, always toward the same star that is infinitely far away).  If we carry it around in a box and then open the box and the arrow seems to point in a different direction, it is the box that has rotated, not the arrow.  From this the orientation of the box can be determined, which is a useful navigational tool in situations where GPS is not available.

Along with Paul Hamilton's group, we are creating a gyroscope based on a trapped ion.  The rules of quantum mechanics that permit objects to be in two places at once also allow us to make a quantum Foucault pendulum, where the ion orbits the trap center clockwise and counterclockwise at the same time.  Matter-wave interference then allows read-out of the orientation of this gyroscope compared to the lab.  If the lab has rotated (hint: it most certainly has!), this effect will be visible in the interference patter.  We are working toward demonstrating this first inertial sensor built from a trapped ion and exploring its usefulness for practical applications.  The hope is that robust, intertial navigation will be possible in GPS denied environments such as underwater, in space, or in the event of a failure of the GPS satellite constellation.