Differential interferometry (DI) with two coupled sensors is a most powerful approach for precision measurements in the presence of strong phase noise. However, DI has been studied and implemented only with classical resources. Here we generalize the theory of differential interferometry to the case of entangled probe states. We demonstrate that, for perfectly correlated interferometers and in the presence of arbitrary large phase noise, sub-shot noise sensitivities — up to the Heisenberg limit — are still possible with a special class of entangled states in the ideal lossless scenario.

M. Landini et al.,
Phase-noise protection in quantum-enhanced differential interferometry
New J. Phys. 16, 113074 (2014)

We demonstrate a tomographic reconstruction algorithm that relies on data collected during the evolution of an unknown quantum state. We estimate the state density matrix as well as the dephasing noise present in the system by assuming complete knowledge of the hamiltonian evolution. Our scheme therefore realizes quantum state tomography but could readily be modified to perform quantum process tomography by assuming complete knowledge of the input states.

C. Lovecchio et al.,
Quantum state reconstruction on Atom-Chips
New J. Phys. 17, 093024 (2015)

Matteo Zaccanti has been awarded with an ERC Starting Grant! The title of the project is "PoLiChroM: Superfluidity and ferromagnetism of unequal mass fermions with 2- and 3-body resonant interactions” (proposal #637738). Congratulations!

We report the realization of a Bose-Einstein condensate of ³⁹K atoms without the aid of an additional atomic coolant. Our route to Bose-Einstein condensation comprises sub-Doppler laser cooling of large atomic clouds and evaporative cooling in an optical dipole trap where the collisional cross section can be increased using magnetic Feshbach resonances. Large condensates with almost 10⁶ atoms can be produced in less than 15 s. Our achievements eliminate the need for sympathetic cooling with Rb atoms, which was the usual route implemented until now due to the unfavorable collisional property of ³⁹K.

M. Landini et al.,
Direct evaporative cooling of ³⁹K atoms to Bose-Einstein condensation
Phys. Rev. A 86, 033421 (2012)

Driving the complex dynamics of physical systems to perform a specific task is extremely useful but challenging in several fields of science, and especially for fragile quantum mechanical systems. Even harder, and often unfeasible, is to invert the time arrow of the dynamics, undoing some physical process. We theoretically and experimentally drive forth and back through several paths in the five-level Hilbert space of a Rubidium atom in the ground state. We achieve such an objective applying optimal control strategies to a Bose-Einstein condensate on an Atom chip via a frequency modulated RF field. We further prove that backward dynamical evolution does not correspond to simply inverting the time arrow of the driving field neglecting the only-system part of the dynamics. Apart from the relevance for the foundations of quantum mechanics, these results are important steps forward in the manipulation of quantum dynamics that is crucial for several physical implementations and very promisingly powerful quantum technologies.

C. Lovecchio et al.,
Optimal preparation of quantum states on an atom chip device
Phys. Rev. A 93, 010304(R) (2016)