QUantum Enhanced Sensing with Trapped ions for Atomic Parity Violation (QUEST for APV)

Summary

The Standard Model (SM) of particle physics describes fundamental interactions between the known particles extremely well. However, it fails to provide answers for big open questions, as the origin and composition of dark matter. The QuEST project aims to develop a novel platform to test the SM, in particular the electroweak sector and search for clues that reveal new physics beyond the SM. The weak force is the only fundamental interaction that is known to break parity symmetry, i.e. inversion of spatial coordinates. In atomic systems, this effect provides a unique window into the weak interaction at low energies, complementing high energy particle physics, and provides a pathway to search for new physics beyond the SM, such as dark bosons. However, the signals revealing atomic parity violation (APV) are incredibly weak and for the last two decades progress on precision tests of atomic parity violation have been hampered by the stringent experimental requirements. In the QuEST project the quantum toolbox is fully exploited to reveal APV in Ba+ for the first time and realize more stringent tests of electroweak theory beyond the current state-of-the-art. The proposed method is based on a pair of quantum-entangled trapped Ba+ ions in a so-called decoherence-free subspace: a state is by design insensitive to noise that is correlated between both ions and immune to common-mode systematic effects. As a result, the experimental requirements can be easily met in the QuEST project and APV can be measured with superior accuracy. The main outcome of the QuEST project is to provide an independent precision low-energy test of the electroweak sector of the SM. At the targeted level of accuracy, result will be able to clearly distinguish between predictions made by the SM and models that include the existance of dark bosons.