A team from Griffith University Centre for Quantum Dynamics received the prestigious 2023 Paul Ehrenfest Best Paper Award for the most significant paper in the foundations of quantum physics published in the preceding five years.
The winning paper, published in Nature Physics, addressed a knowledge gap of the most fundamental kind in physics: What is an ‘observer’?
The research was done by an international team led by Griffith’s Professor Howard Wiseman, Dr Nora Tischler and Associate Professor Eric Cavalcanti,
Associate Professor Cavalcanti was in Vienna to accept the international award from the Austrian Academy of Sciences, at the Institute for Quantum Optics and Quantum Information.
“Quantum theory is one of the pillars of modern physics, but the textbook versions of the theory are really about what observers may observe, not about what exists in the world independent of the observer,” Professor Wiseman said.
“This puts the observer at the heart of quantum physics, which is a famous problem.”
The authors tackled this by proposing an experiment analogous to tests of ‘Bell inequalities’ – experiments involving entangled quantum particles, which were awarded the 2022 Nobel prize in physics.
But there was a twist: now the observers involved in the test were themselves described with the quantum formalism.
“What we showed is that in this carefully prepared setup, the predictions of quantum theory are at odds with three widely held assumptions about how the world works,” Associate Professor Cavalcanti said.
“If the quantum predictions for this setup are confirmed experimentally, one of these assumptions must go. That is, Nature would be proven to be even stranger than what the violation of Bell inequalities taught us. It is a special honour to receive this award at a conference celebrating 60 years of Bell’s seminal work.”
The Paul Ehrenfest Best Paper Award was jointly awarded to the authors of three related papers on the role of the observer in quantum mechanics. According to the award organisers, “these theorems provide new challenges for the interpretation of quantum theory, forcing us to make some hard choices in our conception of quantum reality”.
The Griffith-led paper, A strong no-go theorem on the Wigner’s friend paradox, was published in 2020.
