About QUINST

Quantum mechanics is at the heart of our technology and economy - the laser and the transistor are quantum devices - but its full potential is far from being realized. Recent technological advances in optics, nanoscience and engineering allow experimentalists to create artificial structures or put microscopic and mesoscopic systems under new manipulable conditions in which quantum phenomena play a fundamental role.

Quantum technologies exploit these effects with practical purposes. The objective of Quantum Science is to discover, study, and control quantum efects at a fundamental level. These are two sides of a virtuous circle: new technologies lead to the discovery and study of new phenomena that will lead to new technologies.

Our aim is  to control and understand quantum phenomena in a multidisciplinary intersection of  Quantum Information, Quantum optics and cold atoms, Quantum Control, Spintronics, Quantum metrology, Atom interferometry, Superconducting qubits and Circuit QED and Foundations of Quantum Mechanics.

QUINST is funded in part as a “Grupo Consolidado” from a Basque Government Grant (J. G. Muga is the current PI), and functions as a network of groups with their own funding, structure, and specific goals.  

 

 

Latest events

Prof. Daniel Braun (Universite Paul Sabatier Toulouse) (Seminar)

When and where

12/2011

Description

2010/12/13, Prof. Daniel Braun (Universite Paul Sabatier Toulouse)

Place:  Sala de Seminarios del Departamento de Física Teórica e Historia de la Ciencia
Time: 11:30h.
Title: Decoherence enhanced measurements

Abstract
The major goal of Quantum Enhanced Measurements is to achieve the Heisenberg limit (HL)- a scaling of the sensitivity as 1/N with the number N of quantum resources.  This would represent a major improvement over the standard quantum limit (SQL), in which the sensitivity scales as the inverse square root of N.  However, despite about 30 years of efforts, the SQL has been surpassed only by very few experiments so far and only for small values of N, as the required highly non-classical states are typically very prone to decoherence.

In this talk I show that under certain conditions, decoherence itself can be used as a signal that allows to achieve the HL by using only an initial product state.  After exploring the effect at the example of the measurement of the length of a cavity containing two optical lattices, I put these new type of "decoherence enhanced measurements" into a broader context of
"quantum enhanced interaction measurements".  I will show in particular that the 1/N scaling does not contradict the theorem stating that the SQL cannot be beaten with a product state, and present a general theory that shows the feasibility of a much larger class of precision measurements that use only a product state and achieve the HL, even in the presence of individual decoherence of all subsystems.