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We introduce a novel minimally-disturbing method for sub-nK thermometry in a Bose-Einstein condensate (BEC). Our technique is based on the Bose-polaron model; namely, an impurity embedded in the BEC acts as the thermometer. We propose to detect temperature fluctuations from measurements of the position and momentum of the impurity. Crucially, these cause minimal back-action on the BEC and hence, realize a non-demolition temperature measurement. Following the paradigm of the emerging field of textit{quantum thermometry}, we combine tools from quantum parameter estimation and the theory of open quantum systems to solve the problem in full generality. We thus avoid textit{any} simplification, such as demanding thermalization of the impurity atoms, or imposing weak dissipative interactions with the BEC. Our method is illustrated with realistic experimental parameters common in many labs, thus showing that it can compete with state-of-the-art textit{destructive} techniques, even when the estimates are built from the outcomes of accessible (sub-optimal) quadrature measurements.
We propose experimentally feasible means for non-destructive thermometry of homogeneous Bose Einstein condensates in different spatial dimensions ($din{1,2,3}$). Our impurity based protocol suggests that the fundamental error bound on thermometry at
We study the dynamics of an impurity embedded in a trapped Bose-Einstein condensate (Bose polaron), by recalling the quantum Brownian motion model. It is crucial that the model considers a parabolic trapping potential to resemble the experimental con
We show that the Kapitza stabilization can occur in the context of nonlinear quantum fields. Through this phenomenon, an amplitude-modulated lattice can stabilize a Bose-Einstein condensate with repulsive interactions and prevent the spreading for lo
We study the decay mechanism of the gapped lowest-lying excitation of a quasi-pure box-trapped atomic Bose-Einstein condensate. Owing to the absence of lower-energy modes, or direct coupling to an external bath, this excitation is protected against o
We have studied the decay of a Bose-Einstein condensate of metastable helium atoms in an optical dipole trap. In the regime where two- and three-body losses can be neglected we show that the Bose-Einstein condensate and the thermal cloud show fundame