Quantum-limited metrology and Bose-Einstein condensates

Sergio Boixo, Animesh Datta, Matthew J. Davis, Anil Shaji, Alexandre B. Tacla, Carlton M. Caves

Published 2009-06-04, updated 2009-08-18Version 3

We discuss a quantum-metrology protocol designed to estimate a physical parameter in a Bose-Einstein condensate of N atoms, and we show that the measurement uncertainty can decrease faster than 1/N. The 1/N scaling is usually thought to be the best possible in any measurement scheme. From the perspective of quantum information theory, we outline the main idea that leads to a measurement uncertainty that scales better than 1/N. We examine in detail some potential problems and challenges that arise in implementing such a measurement protocol using a Bose-Einstein condensate. We discuss how some of these issues can be dealt with by using lower-dimensional condensates trapped in nonharmonic potentials.