# Berlin 2014 – wissenschaftliches Programm

## Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

# Q: Fachverband Quantenoptik und Photonik

## Q 62: Precision measurements and metrology IV

### Q 62.3: Vortrag

### Freitag, 21. März 2014, 14:45–15:00, DO24 1.101

**Multiparticle singlet states and their metrological applications** — •Iñigo Urizar-lanz^{1}, Zoltán Zimboras^{1}, Iagoba Apellaniz^{1}, and Géza Tóth^{1,2,3} — ^{1}Theoretical Physics, The University of the Basque Country, E-48080 Bilbao, Spain — ^{2}IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao, Spain — ^{3}Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary

Singlet states are quantum states of vanishing angular momentum.
When composing the angular momenta of two spin-*j* particles, there appears a unique singlet state,
however, for an ensemble of *N* particles there exists a plethora of different
types of singlets. We present a partial classification of them, and then focus
on the permutationally invariant (PI) ones. Their basic properties and
characterization is presented, and some specific PI singlets are
studied for metrological applications. In particular, we calculate
the maximal achievable accuracy when measuring the gradient of a
magnetic field using these states. Moreover, we single out a measurement
set-up that saturates the bound given by the quantum Fisher Information.