Year: 2011
Type: article
Abstract: We consider the smallest possible directional reference frames allowed and determine the best one can ever do in preserving quantum information in various scenarios. We find that for the preservation of a single spin state, two orthogonal spins are optimal primitive reference frames; and in a product state, they do approximately $22%$ as well as an infinite-sized classical frame. By adding a small amount of entanglement to the reference frame, this can be raised to $2(2/3){}^{5}=26%$. Under the different criterion of entanglement preservation, a very similar optimal reference frame is found; however, this time it is for spins aligned at an optimal angle of ${87}^{\ifmmode^\circ\else\textdegree\fi{}}$. In this case $24%$ of the negativity is preserved. The classical limit is considered numerically, and indicates under the criterion of entanglement preservation, that ${90}^{\ifmmode^\circ\else\textdegree\fi{}}$ is selected out nonmonotonically, with a peak optimal angle of ${96.5}^{\ifmmode^\circ\else\textdegree\fi{}}$ for $L=3$ spins.
Source: Physical Review A
Author: David Jennings
Institution: Imperial College London
Language: English
Subfield: Artificial Intelligence
Field: Computer Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1586883587