Pushing the limits of atom interferometry...The system we want to realize is a Mach-Zender spatial interferometer operating with trapped Bose-Einstein condensates (BECs). Phase diffusion caused by interatomic collisions are suppressed implementing BECs with tunable interactions in ultra-stable optical potentials. Entangled states can be used to improve the sensitivity of the sensor beyond the standard quantum limit to ideally reach the ultimate, Heisenberg, limit set by quantum mechanics. Our project aims at developing a sensor with unprecedented spatial resolution able to compete with, and eventually overcome, state-of-the-art interferometers with cold (non condensed) atomic waves.

Observed a Quantum Phase Transition with parity-symmetry breaking

We report the experimental observation of the full phase diagram across a transition where the spatial parity symmetry is broken. Our system consists of an ultra-cold gas of 39K with tunable interactions trapped in a double-well potential. At a critical value of the interaction strength, we observe a continuous quantum phase transition where the gas localizes in one well or the other, thus breaking the underlying symmetry of the system. Furthermore, we show the robustness of the asymmetric state against controlled energy mismatch between the two wells. This is the result of hysteresis associated with an additional discontinuous quantum phase transition that we fully characterize. Our results pave the way to the production of a broad class of quantum entangled states including Schroedinger cat states with macroscopic atom number.

A. Trenkwalder et al.,
Quantum phase transition with parity-symmetry breaking and hysteresis
Nature Phys. 12, 826 (2016)

K2 people

Leonardo Masi
PhD student
Giovanni Ferioli
PhD student
Giulia Semeghini
Postdoc
Giovanni Modugno
Scientific staff
Massimo Inguscio
Scientific staff
Marco Fattori
Scientific staff
Former members:
Simon Coop
Manuele Landini
Sanjukta Roy
Giacomo Spagnolli
Andreas Trenkwalder

K2 contacts

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

Marco Fattori
(fattori@lens.unifi.it)

K2 funding

ERC StG AISENS
EU FP7 QIBEC
FIRB Futuro in Ricerca
2010 RBFR08H058_001
INFN Progetto Premiale
Atom Interferometer