Article
Rabi interferometry and sensitive measurement of the CasimirPolder force with ultracold gases
Physical Review A (Impact Factor: 3.04). 09/2010; 82(3). DOI: 10.1103/PhysRevA.82.032104
Source: arXiv

Article: Quantum interferometry at zero and finite temperature with twomode bosonic Josephson junctions
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ABSTRACT: We analyze phase interferometry realized with a bosonic Josephson junction made of trapped dilute and ultracold atoms. By using a suitable phase sensitivity indicator we study the zero temperature junction states useful to achieve sub shotnoise precisions. Sub shotnoise phase shift sensitivities can be reached even at finite temperature under a suitable choice of the junction state. We infer a scaling law in terms of the size system (that is, the number of particles) for the temperature at which the shotnoise limit is not overcome anymore11/2012;  [Show abstract] [Hide abstract]
ABSTRACT: We demonstrate that the thermal CasimirPolder forces on molecules near a conducting surface whose transition wavelengths are comparable to the moleculesurface separation are dependent on the ambient temperature and molecular polarization and they can even be changed from attractive to repulsive via varying the temperature across a threshold value for anisotropically polarizable molecules. Remarkably, this attractivetorepulsive transition may be realized at room temperature. Let us note that the predicted repulsion is essentially a nonequilibrium effect since the force we calculated on a groundstate (or an excitedstated) molecule actually contains the contribution of the absorption (or emission) of thermal photons.Physical Review A 11/2012; 86(5). · 3.04 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We study an ultracold gas of $N$ bosons trapped in a one dimensional $M$site optical lattice perturbed by a spatially dependent potential $g\cdot x^j$, where the unknown coupling strength $g$ is to be estimated. We find that the measurement uncertainty is bounded by $\Delta g\propto\frac1{N (M^j1)}$. For a typical case of a linear potential, the sensitivity improves as $M^{1}$, which is a result of multiple interferences between the sites  an advantage of multipath interferometers over the twomode setups. Next, we calculate the estimation sensitivity for a specific measurement where, after the action of the potential, the particles are released from the lattice and form an interference pattern. If the parameter is estimated by a leastsquare fit of the average density to the interference pattern, the sensitivity still scales like $M^{1}$ for linear potentials and can be further improved by preparing a properly correlated initial state in the lattice.Physical Review A 10/2012; 87(3). · 3.04 Impact Factor
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