In the first part of the project, general properties of phonons in BECs for quantum sensing have been analysed. A focus has been particularly on the influence of an internal decay process, three-body loss, which leads to the loss of three atoms from the condensate. A result of the work for this project has been that three-body loss leads to strong restrictions of the utility of phonons in BECs for quantum sensing. The analysis and the results have been published in an article (available as open access on the preprint server Arxiv) and presented at workshops and conferences.
In another part of the project, an optomechanical setup of light coupled to phonons in BECs has been theoretically developed. Furthermore, the utility of the setup has been investigated. It has been found that it will be very hard to achieve quantum sensing with the setup in general and the classical sensing abilities for example applications like gravity-gradiometry are very limited due to practical limitations. The results have been published in a pre-print article that will be sent to a journal soon.
It has also been investigated if optomechanical systems (of which the one based on phonons in BECs is only one explicit example) can be used for sensing of the gravitational field of light. In this context, an explicit proposal was developed based on a different implementation of optomechanics with a levitated solid-state object. The results have been published as pre-print and are under revision by New Journal of Physics.
Another category of gravitational effects are local effects of the cosmological expansion. If those may be observable when quantum sensing is employed has been investigated as part of this project. It has been shown that the effects are far from measurable and a publication has been uploaded to a preprint repository and submitted for peer reviewing to the journal Classical and Quantum Gravity.
The Quantum Klystron, a novel technique to manipulate cold atoms (the constituents of a BEC) has been theoretically developed in another sub-project. The proposal can be implemented with state-of-the-art technology. These results have been published in Physical Review Research. As part of this project, the ER has contributed an experimental investigation of dipole-dipole interactions within a BEC and to an upcoming publication about the topic.
For further dissemination of the results of the project, the two outreach projects “Gravitational fields of motion” and “Sciddle - PhoQuS-G Edition” have been commissioned and supervised.
