Description:

Specially prepared quantum states of alkali atoms can have exotic properties that can be tailored to produce extremely sensitive quantum sensors.  In this talk, I will describe two types of such states.  In the first type, all atoms are placed in a quantum state where the spins of the nucleus and the outer-most electron in each atom are anti-aligned.  When these atoms are dressed by a laser detuned from an optical transition and placed inside a cavity, the resulting system produces the superluminal laser, which is highly dispersive, with a group velocity larger than the vacuum speed of light by a factor as large as a million, without violating special relativity.  Such a laser is extremely sensitive to variations in the cavity length.  Applications of the superluminal laser include search for dark matter, as well as ultrasensitive rotation sensing for GPS denied navigation and test of general relativity via precision measurement of the gravitational frame dragging effect.  In the second type, a maximally entangled Schroedinger cat state of atoms is produced via the process of spin squeezing mediated by an optical field in a high-finesse cavity.  In addition to applications in precision time keeping and rotating sensing, this state can be used to search for violation of the equivalence principle, a key tenet of general relativity, via dual species atom interferometry, at a level that is six orders of magnitude better than the current limit. 

Selim Shahriar, Professor, Department of Electrical and Computer Engineering, Northwestern University

Host: Anupam Garg