Reduced Quantum-Reference-Frame Channels for Open Quantum Systems
Arxiv pre-print (July 2026).
My research revolves around conceptual questions at the interface of quantum theory and gravity. Primarily, I study these topics through the lens of quantum reference frames, which allow us to understand physics in a relational manner even in absence of classical rods and clocks. I am also curious about how to make sense of foundational notions like events and causal order in absence of a fixed spacetime background, and how we partition the world into subsystems.
What excites me about this research direction is not only the foundational nature of the questions but also that it requires input from many different communities: from quantum foundations and quantum information to quantum gravity and the philosophy of physics.
When describing a physical system, it is very common to do so with respect to a reference frame - a ruler used to determine the position of a particle, for example, or a clock, which tracks the time that elapses while it is moving. Usually, reference frames are treated as purely classical objects with well-defined properties. Yet, ultimately, all material systems should be describable by quantum theory. The study of quantum reference frames (QRFs) investigates what happens when we take into account the quantum properties of the reference frame itself. It aims to answer questions such as:
Usually, the order between two events A and B is fixed: either A happens before B or B happens before A. In quantum theory, this may no longer be the case. The phenomenon of indefinite causal order captures processes, in which the events occur in a superposition of different orders or even stranger configurations. An interesting question in this area is how to embed processes with indefinite causal into spacetime. This requires a careful reconsideration of what we mean by 'events' and the order between them when we no longer have fixed, classical particle trajectories or spacetime geometries.
As we describe the world, we almost invariably partition it into subsystems. Often, we treat these subsystems as isolated and assume that we can neglect any interaction with the outside world. Yet, there are limitations to this view. General relativity teaches us that gravity cannot be shielded. This implies that all systems, except possibly the universe as a whole, are gravitationally open systems.
Moreover, the presence of local symmetries in gauge theory and gravity warrants further caution in dealing with subsystems. While gauge degrees of freedom can otherwise be regarded as redundant, they become central when considering subregions as part of a larger system. In this case, so-called edge modes - gauge degrees of freedom at the boundary of the subregion - encode information required to couple the region to its surroundings. The study of edge modes thus becomes crucial for understanding subsystems in the presence of symmetries.
Arxiv pre-print (July 2026).
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Communications Physics (August 2023). Featured in Epsiloon Magazine: "Métaphysique quantique: les premières expériences."