Phase control of entangled states
Entanglement is a fundamental quantum feature which plays an important role in quantum information and quantum computing. In recent years, many efforts have been done for understanding the survival of quantum entanglement in open systems at high temperature.
In this work, we consider a quantum system of two coupled parametric oscillators in contact with a common heat bath and with a time dependent coupling term. We demonstrate that the oscillators become entangled exactly in the region where the classical counterpart, a Mathieu oscillator, is unstable. The instability regions of the system have been theoretically and experimentally explored by means of a weak sinusoidal perturbation, with adjustable amplitude and phase, applied to
the oscillation frequency. We show that if the classical system passes from stable to unstable regions as a consequence of the perturbation, the quantum oscillators become entangled. This means that it is possible to generate and manipulate entanglement controlling the dynamical behaviour of the associated classical system.
CYBERNETICS AND PHYSICS, Vol. 4, No. 3. 2015, 78-81.