Research Summaries

Back T^3 scaling in Atom Interferometer Sensors

Fiscal Year 2017
Division Graduate School of Engineering & Applied Science
Department Physics
Investigator(s) Narducci, Francesco A.
Sponsor Office of the Secretary of Defense (DoD)
Summary Inertial sensors based on atom interferometers have tremendous potential to improve the Navy's ability to precisely navigate in GPS-compromised environments. These interferometers are comprised of atoms that are specially prepared in very specific atomic states, subjected to pulses of light separated by a time T and then measured. The measurement reveals interference fringes which contain information about inertial forces, such as acceleration and rotation. The phase of the fringes, and hence the sensitivity, in "conventional" atom interferometers scales as the time between pulses, T, squared. This scaling implies that if the time between pulses is increased by a factor two, the fundamental sensitivity of the interferometer improves by a factor of 4. Recently, the PI has begun to explore novel atom interferometer configurations in which the interference fringe phase scales as T cubed, rather than T squared. This scaling implies that the fundamental sensitivity of an atom interferometer will improve by a factor of 8, rather than 4, if the time T is doubled. The PI has shown that the improved scaling can be achieved when the symmetry between the two arms of the interferometer is broken. "Conventional" interferometers assume that the inertial forces acting on the atoms is the same in the two arms. However, if the forces are not the same, higher order scaling can be achieved. Through the use of different magnetically sensitive atomic states and gradient magnetic fields, the acceleration experienced by atoms is different in the two arms and hence the symmetry of the interferometer is broken. Researchers at Stanford University, in the group of Mark Kasevich, have also investigated T-cubed scaling in interferometers but whose origin is due to gravity gradients. The work to be performed that is outlined in the proposal will be a collaborative effort between NPS and Stanford to theoretically and experimentally explore the effects of magnetic field gradients and gravity gradients on T scaling in atom interferometers.
Keywords atom interferometry inertial sensing
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