The Paul Ehrenfest Best Paper Award for Quantum Foundations recognizes outstanding and influential research contributions to the foundations of quantum physics. The award aims to raise awareness for the quantum foundations field and draw attention to new and interesting achievements in this area without delay. It is awarded for the most significant paper in the foundations of quantum physics, theoretical or experimental, published in a peer-reviewed journal in the five calendar years before the prize call (i.e., this year, we accepted submissions published between January 1st, 2020, and December 31st, 2024). Other than that, papers from all areas in the foundations of quantum physics and by authors of any background will be eligible for the award.

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The Paul Ehrenfest Best Paper Award 2025 has been awarded to: 

The committee of the 2025 Ehrenfest Award is pleased to announce that this year’s award goes to the paper “The Trinity of Relational Quantum Dynamics” by Philipp A. Höhn, Alexander R. H. Smith, and Maximilian P. Lock, in recognition of its important contribution to the foundations of relational quantum theory. The paper establishes the equivalence of three major approaches to relational dynamics: Dirac observables, the Page–Wootters formalism, and quantum deparametrization. It resolves longstanding criticisms of the Page–Wootters formalism, clarifies the role of quantum clocks and temporal reference frames, and unifies previously fragmented approaches to the problem of time in quantum gravity.

The 2025 selection committee consisted of:

• Matteo Fadel, ETH Zurich, Switzerland
• Lluis Masanes, University College London, UK
• Lorenza Viola, Dartmouth College, New Hampshire, USA
• Cyril Branciard, Institut Néel, France
• Peter Asenbaum, IQOQI Vienna, Austria