ELFT HÍRADÓ

[Gergely Szirmai <szirmai.gergely AT wigner.mta.hu>]

 Tisztelt Kollégák!

A következő Wigner kollokviumi előadás április 29-én, pénteken
11:00 órakor kezdődik a KFKI campus 1. épület tanácstermében.

Kérem figyeljenek a rendhagyó időpontra!

Cím/Title: Random states for robust quantum metrology

Előadó/Speaker: Prof. Maciej Lewenstain (ICFO - The Institute of Photonic
Sciences)

Kivonat/abstract

We study how useful random states are for quantum metrology, i.e., surpass
the classical limits imposed on precision in the canonical phase estimation
scenario. First, we prove that random pure states drawn from the Hilbert
space of distinguishable particles typically do not lead to super-classical
scaling of precision even whenallowing for local unitary optimization.
Conversely, we show that random states from the symmetric subspacetypically
achieve the optimal Heisenberg scaling without the need for local unitary
optimization. Surprisingly,the Heisenberg scaling is observed for states of
arbitrarily low purity and preserved under finite particle losses.
Moreover, we prove that for such states a standard photon-counting
interferometric measurement suffices to typically achieve the Heisenberg
scaling of precision for all possible values of the phase at the same time.
Finally, we demonstrate that metrologically useful states can be prepared
with short random optical circuitsgenerated from three types of
beam-splitters and a non-linear (Kerr-like) transformation.
http://arxiv.org/1602.05407

Részletek/Details: https://indico.kfki.hu/event/388/


Üdvözlettel

Szirmai Gergely