Spin Squeezing

Precession measurement is a key requirement to overcome quantum projection noise below the Standard Quantum Limit (SQL). In this regard, spin squeezed state (SSS) can obtain high precision by manifestation of the Heisenberg uncertainty principle, where precision in one observable necessarily leads to increased uncertainty in its conjugate observable. In order to create such a state, Quantum Nondemolition (QND) measurement has been proposed to create SSS, in which QND measurement provides information about one component of the angular momentum without introducing significant noise, leading to the creation of a spin squeezed state. During the presentation, creation of SSS by QND measurements will be elaborated in more details.