Dynamic control of quantum entanglement: from discrete to continuous variables – Niels Bohr Institute - University of Copenhagen

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Dynamic control of quantum entanglement: from discrete to continuous variables

The challenges of manipulating internal and translational entangled states of quantum objects in noisy environments will be elucidated. New aspects of quantum measurements will be discussed.

In this lecture we study the dynamical control of an entangled multipartite system coupled to a bath. Such a system undergoes rapid disentanglement in many realistic scenarios due to local, symmetry-breaking differences in the particle-bath couplings. We show that locally controlled perturbations, addressing each particle individually, can impose a symmetry allowing the existence of decoherence-free multipartite entangled systems [1].

We next show that particles subject to fields that couple their internal and translational (momentum) states may undergo a crossover from randomization (diffusion) to strong localization (sharpening) of their momentum distribution. The predicted crossover should be manifest by a drastic change of the interference pattern as a function of the coupling fields [2].

We finally explore the feasibility of creating a translationally entangled state for massive particles, and its use for matter wave teleportation [3]. To this end, we study collisions as a tool for generating translational entanglement. In one-dimensional scattering, resonances are shown to determine the degree of postcollisional entanglement [4]. New results show that frequent probing protects/freezes such motional states.

  

[1] G. Gordon and G. Kurizki, Phys Rev Lett 97, 110503(2006).

[2] N. Bar-Gill and G. Kurizki,  Phys. Rev. Lett. 97, 230402 (2006).[3] L. Fisch and G. Kurizki, Europhys. Lett. 75, 847(2006).[4] A. Tal and G. Kurizki, Phys. Rev. Lett. 94, 160503 (2005).