QuEST for APV · Quantum Enhanced Sensing with Trapped ions for Atomic Parity Violation

The Standard Model (SM) of particle physics classifies the known particles and describes their non-gravitational interactions extremely well. However, it fails to provide answers to various big open questions, such as the origin of dark matter. The QuEST project aims to break new ground in fundamental physics by probing the electroweak (EW) sector of the SM. The weak force is the only fundamental interaction that is known to break spatial mirror symmetry known as parity. In atomic systems, parity violation provides a unique window into electroweak interactions at low energies, complementary to high energy particle physics. However, the signals stemming from atomic parity violation (APV) are incredibly weak and, for the last two decades, progress on low-energy EW tests have been hampered by the daunting experimental requirements to detect APV. In this proposal, I fully exploit the quantum toolbox to reveal APV in Ba+ for the first time. The employed method is based on a pair of Ba+ ions in a quantum-entangled state that is by design insensitive to correlated noise and immune to common-mode systematic effects. This significantly eases the experimental requirements and enables a measurement of APV with a superior accuracy. The main outcome of QuEST is to provide a first independent precision low-energy test of the electroweak sector of the SM in nearly 20 years. The targeted level of accuracy will go beyond the current state-of-the-art and will allow for sensitive search for new physics beyond the SM, where QuEST will probe for processes at an energy scale of up to ~10 TeV. The results will provide information on nuclear structure, relevant for astrophysics, and will impact the field of quantum information science. Therefore, QuEST is a unique platform with an interdisciplinary character that will shape the landscape of low-energy electroweak tests of the SM for many years to come.