Quantum measurement with cold atoms

Project funded by Hellenic Foundation for Research and Innovation (HFRI), grant 768. Participating organisations named by the source: ΙΤΕ. Funded amount: EUR 164,000, as stated by the source. Source: OpenAIRE Graph, from the funder's project data (collected by OpenAIRE on 2026-02-19); national funding data, not CORDIS. Abstract given by the source: Ultracold atoms have demonstrated great prospects for both technological and fundamental science applications. In order to fully exploit their potential, a precise control of the atomic cloud that can manipulate the quantum features and harness quantum resources is required. The proposed research aims to develop a robust method for measurement and control of the atom number in an ultracold atomic ensemble with precision better than the atom shot noise level. The measurement is based on the Faraday paramagnetic effect: off-resonant light, when traveling through a polarized atomic cloud, experiences optical rotation at an angle that is proportional to the number of atoms. The proposed measurement does not destroy quantum coherences and has an insignificant effect on the atomic temperature, so that it can be used to perform quantum-enhanced measurements and prepare the atomic state at the start of an interferometer sequence. Control of the atom number is realized by the unavoidable atom-loss that is introduced by the measurement, since even far off-resonant light has a non-zero probability for absorption. This atom-loss mechanism will be employed to shrink an initial ensemble to the targeted size. With the proposed method for the first time the quantum back-action of the measurement probe is exploited to improve the stability of the experiment. Measuring with sub-atom-shot noise resolution will lead to number squeezed states of Bose Einstein Condensates and will pave the way for squeezing and entanglement generation for spectroscopy and interferometry. The measurement sensitivity and the realized squeezing are fundamentally limited by the photon shot noise of the probe light. In order to overcome this limitation, we will use an optical resonator to enhance the signal from the ensemble. Applications of the proposed research include atomic clocks, inertial sensors, quantum computing, quantum simulations and fundamental physics experiments such as gravitational detectors.

Original source.

Source: OpenAIRE Graph: projects of national funders, OpenAIRE, from the project data of Hellenic Foundation for Research and Innovation (HFRI). Retrieved 2026-10-22. Licence: Creative Commons Attribution 4.0 (OpenAIRE Graph). Selected metadata, adapted presentation; the publisher's record is authoritative. No endorsement by the source is implied. Licence: Creative Commons Attribution 4.0 (CC BY 4.0).

AI-assisted summary: The project "Quantum measurement with cold atoms" is funded by the Hellenic Foundation for Research and Innovation with a grant of EUR 164,000. It aims to develop a method for precise measurement and control of atom numbers in ultracold atomic ensembles. Suggested technology pillar: sensing. Generated by AI from the public source text; it may contain errors and the original source is authoritative.