Atoms few, damned but quick... Magnetic fields sources, RF antennas, optical structures, all integrated in a micro-chip with a Bose-Einstein condensate a few hundred microns from the surface: an "Atom chip". The benefits are higher trap frequencies, shorter evaporative time, better atom-field coupling plus a much (much) cheaper set-up. The goal of our experiment is to make the best use of Atom chips for quantum technological applications.

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)

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)

It is generally impossible to probe a quantum system without disturbing it. However, it is possible to exploit the back-action of quantum measurements and strong couplings to tailor and protect the coherent evolution of a quantum system. This is a profound and counterintuitive phenomenon known as quantum Zeno dynamics (QZD). Here we demonstrate QZD with a rubidium Bose-Einstein condensate in a five-level Hilbert space. We harness measurements and strong couplings to dynamically disconnect different groups of quantum states and constrain the atoms to coherently evolve inside a two-level subregion. In parallel to the foundational importance due to the realization of a dynamical superselection rule and the theory of quantum measurements, this is an important step forward in protecting and controlling quantum dynamics and, broadly speaking, quantum information processing.

F. Schӓfer et al.,
Experimental realization of quantum zeno dynamics
Nat. Commun. 5, 3194 (2014)

S. Gherardini et al.,
Ergodicity in randomly perturbed quantum systems
arXiv:1604.08518 (2016)

Micro-Rb people

Hoang-Van Do
PhD student
Cosimo Lovecchio
Postdoc
Francesco Saverio
Cataliotti

Scientific staff
Former members:
Saverio Bartalini
Shahid Cherukattil
Luigi Consolino
Vera Guarrera
Ivan Herrera
Pietro Lombardi
Ali Khan Murtaza
Jovana Petrovic
Florian Schäfer

Micro-Rb contacts

For further information, request of material, job opportunities, please contact:

Francesco Saverio Cataliotti
(fsc@lens.unifi.it)

Micro-Rb funding

FIRB Futuro in Ricerca
2008 HYTEQ
PRIN2010-2011