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Introduction
AC Stark effect was discovered by Stark in 1913. The dynamic Stark effect or AC stark effect is the quasi static shift in energy levels due to the application of optical fields. The effect is similar to the static Stark effect in many ways. However, the AC Stark effect can be applied on rapid time scales and with high energies when compared to those of atoms and molecules. The AC Stark effect due to non-resonant laser fields is used in contemporary experiments to shape potential energy surfaces,to hold and align molecules, and to make rapid transient birefringence. Five approaches are used to describe the dynamic Stark effect.

Definition
The Stark effect is the shift of energy levels due to the presence of an external electric field. In the oscillating electric fields produced by lasers a similar effect is occurred. If the field oscillates with a lower frequency, the level shifts adiabatically following the static Stark shift formula. If the frequency is increased,the eigen states do not follow the instantaneous electric field, instead follow only the intensity envelope of the field under appropriate conditions. This quasi static shift of the eigen states in the presence of an oscillating field is known as the AC Stark effect or dynamic Stark effect.

Uses
Modern ultrafast lasers can interact with many quantum systems on their intrinsic time and energy scales. As a result, the influence of these lasers through the dynamic Stark effect has become an important part of molecular, atomic, and optical physics. This type of influence will not be accessible with DC approaches. The effect is used in a set of exciting new molecular experiments that shape potential energy surfaces, hold and align molecules, and use quantum superpositions for generating macroscopic time-dependent birefringences to modify propagating pulses. The dynamic Stark effect is an important tool for controlling and measuring quantum systems.It is mainly useful for quantum control because the mechanism is nonresonant requiring no highly specific wavelength sources and also because it can be non perturbative causing a huge change in target systems.