Singlet-aided infinite resource reduction in the comparison of distant fields
Sougato Bose, S. F. Huelga, Martin Bodo Plenio · Physical Review A · 2001
We present a task that can be faithfully solved with finite resources only when aided by particles prepared in a particular entangled state: the singlet state. The task consists of identifying the mutual parallelity or orthogonality of weak distant magnetic fields whose absolute directions are completely unknown.