Relativity of quantum superpositions in the context of superpositions of gravitational sources

Abstract: It is anticipated that in a theory of quantum gravity, there exist quantum superpositions of semiclassical states of spacetime geometry. It is often discussed how such states could arise from a source mass in a spatial superposition. In this talk I will discuss such spatial superposition scenarios from the perspective of relativity of the notion of location, and thus of superposition itself. This perspective allows to show that for states in which the superposed amplitudes differ by a coordinate transformation, it is always possible to re-express the scenario in terms of dynamics on a fixed geometry albeit with adapted preparations and measurements on the involved degrees of freedom. The results unveil an ambiguity in the interpretation of such scenarios as genuinely quantum-gravitational, and motivate further research into loopholes and assumption behind such scenarios.

general relativity and quantum cosmologyquantum physics

Audience: advanced learners

Comments: Talk not recorded

---

Tricontinental Quantum Fundamentals Seminar

Series comments: The Tricontinental Quantum Fundamentals Seminar (3C-QFS) is an online seminar series connecting researchers from Australia, Europe, and America. Our goal is to facilitate discussion between the three continents and bring together those working on foundational topics in relativistic quantum physics, covering but not limited to:

• Measurement, localisation, and causality in relativistic quantum theory
• Energy conditions and quantum inequalities
• Non-locality and observer-dependence of entanglement
• Quantum reference frames and symmetries in quantum theory
• Holography, AdS/CFT, and analogue gravity

For 3C-QFS, we wish to foster an inclusive community and promote open discussion by encouraging a casual atmosphere during the seminars.

The seminars are held online via Zoom, consisting of 40-60 minute talks followed by additional time for questions. We meet every three weeks on Tuesday, alternating between two times in order to connect research communities across two of the three continents.

For those unable to join the seminars live, talks are recorded and hosted on the 3C-QFS YouTube channel.

The seminar series is primarily for students and academics active in the foundations of physics. To sign up for the mailing list and join the seminars live, please complete the registration form on the 3C-QFS website.

---