Mean field energy and bubble formation. The cloud is initially prepared in the FV with all atoms in |↑⟩ (A). Although the single spin state |↓⟩ is energetically lower (E↓E↑) at the center of the cloud, the situation is opposite in the low density tails. The interface (domain wall) between oppositely magnetized ferromagnetic regions has positive (kinetic) energy, which adds to the double minimum energy landscape emerging from the ferromagnetic interaction. Macroscopic tunneling can take place in resonance with the bubble state (B), which has a bubble |↓⟩ at the center. The base energy gain offsets the energy cost of the domain wall. The crossing of the barrier can be triggered by quantum fluctuations in the case of zero temperature (solid arrow) or by thermal fluctuations at finite temperature (empty arrow). After the tunneling process, the bubble increases in size in the presence of dissipation to reach the true vacuum (TV) state (C), without returning to (A). Credit: Natural physics (2024). DOI: 10.1038/s41567-023-02345-4
An experiment carried out in Italy, with theoretical support from Newcastle University, has produced the first experimental evidence of vacuum decay.
In quantum field theory, when a not-so-stable state transforms into a true stable state, it is called a “false vacuum decay.” This occurs through the creation of small localized bubbles. Although existing theoretical work can predict how often this bubble formation occurs, there is little experimental evidence.
Now an international research team involving scientists from Newcastle University has observed the formation of these bubbles in carefully controlled atomic systems for the first time. Published in the journal Natural physicsThe results provide experimental evidence for the formation of bubbles by false vacuum decay in a quantum system.
The results are supported by both theoretical simulations and numerical models, confirming the quantum field origin of decay and its thermal activation, paving the way for the emulation of non-equilibrium quantum field phenomena in atomic systems.
The experiment uses a supercooled gas at a temperature less than one microKelvin compared to absolute zero. At this temperature, bubbles appear as the vacuum decays and Professor Ian Moss and Dr Tom Billam of Newcastle University were able to show conclusively that these bubbles are the result of thermally activated vacuum decay .
Ian Moss, Professor of Theoretical Cosmology at Newcastle University’s School of Mathematics, Statistics and Physics, said: “Vacuum decay is thought to play a central role in the creation of space, time and matter during the Big Bang, but until now there have been no experimental tests. In particle physics, the vacuum decay of the Higgs boson would alter the laws of physics, producing what has been described as the “ultimate ecological catastrophe”.
Dr Tom Billam, Senior Lecturer in Applied/Quantum Mathematics, added: “Using the power of ultracold atom experiments to simulate analogues of quantum physics in other systems – in this case, the universe primitive itself – is a very exciting area of research at the moment. moment.”
The research opens new avenues in understanding the early universe, as well as ferromagnetic quantum phase transitions.
This groundbreaking experiment is just the first step in exploring vacuum decay. The ultimate goal is to find vacuum decay at absolute zero temperature, where the process is driven solely by quantum vacuum fluctuations. This is exactly what an experiment in Cambridge, supported by Newcastle as part of a national QSimFP collaboration, aims to do.
More information:
A. Zenesini et al, False vacuum decay via bubble formation in ferromagnetic superfluids, Natural physics (2024). DOI: 10.1038/s41567-023-02345-4
Provided by Newcastle University
Quote: New research sheds light on phenomenon known as ‘false vacuum decay’ (January 22, 2024) retrieved January 23, 2024 from
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