1.
Phys Rev Lett
; 87(16): 167901, 2001 Oct 15.
Artigo
em Inglês
| MEDLINE
| ID: mdl-11690243
RESUMO
A single quantum system, such as a hydrogen atom, can transmit a Cartesian coordinate frame (three axes). For this it has to be prepared in a superposition of states belonging to different irreducible representations of the rotation group. The algorithm for decoding such a state is presented, and the fidelity of transmission is evaluated.
2.
Phys Rev Lett
; 86(18): 4160-2, 2001 Apr 30.
Artigo
em Inglês
| MEDLINE
| ID: mdl-11328120
RESUMO
We consider the use of N spin-1/2 particles for indicating a direction in space. If N>2, their optimal state is entangled. For large N, the mean square error decreases as N-2 (rather than N-1 for parallel spins).