###Quantum feedback control for fundamental tests of quantum gravity
Project ID: 2228bd1095 (You will need this ID for your application)
Research Theme: Quantum Technologies
UCL Lead department: Physics and Astronomy
Lead Supervisor: Alessio Serafini
Project Summary:
The emergence of proposals to test the quantum nature of linearised gravity has recently shaken the landscape of research into quantum gravity and spurred a lively thread of foundational debates. Such tests, first envisaged by Bose and co-workers and, simultaneously, by Marletto and Vedral, hinge on the generation of quantum superpositions and quantum entanglement mediated by extremely weak (gravitational) interactions and are thus exceptionally demanding in terms of the noise suppression and experimental control they require.
This project aims at boosting the feasibility of these tests by applying the sophisticated toolbox of quantum control theory to the optimised generation of genuine quantum resources. In particular, the student will consider quantum continuous variables, as natural in the context of linearised gravity, and apply a general quantum feedback framework recently developed by one of the PIs. Thus, the generation of Schrödinger cat states as well as of Gaussian and non-Gaussian entanglement will be optimised both through measurement-based feedback (where the information steering the feedback loop is turned from quantum to classical by a measurement) and through “coherent” feedback (where the information stays quantum at all stages).
Hence, the project will turn on the optimised detection of such nonclassical signatures through practical measurement devices, which may also have an impact on quantum metrology and sensing. At this stage, the project will follow potential ramifications either towards fundamental or practical analyses. The former could lead to general reflections on linearised gravity tests and their possible extension to effective theories of quantum gravity at low energies. Alternately, the student could investigate the implementation of the tests in concrete set-ups, such as opto-mechanical systems or Bose-Einstein condensates.
This project will require the student to acquire a background in quantum information, in its application to quantum gravity at low energies and in the theory of quantum control.