Motional squashed states
Stefano Mancini, David Vitali, Paolo Tombesi · Journal of Optics B Quantum and Semiclassical Optics · 2000
We show that by using a feedback loop it is possible to reduce the fluctuations in one quadrature of the vibrational degree of freedom of a trapped ion below the quantum limit. The stationary state is not a proper squeezed state, but rather a squashed state, since the uncertainty in the orthogonal quadrature, which is larger than the standard quantum limit, is unaffected by the feedback action.