Research projects | Homepage of Laura Dreissen

QUantum Enhanced Sensing with Trapped IONs (QUESTIONs)

Fri, 31 Mar 2023 00:00:00 +0000

Summary

This project aims to develop a scalable quantum-enhanced trapped-ion sensor that goes beyond the current state of the art. The sensor is based on quantum metrology of entangled states in singly-ionized barium (Ba$^+$) ions: an atomic system that is especially well suited for this novel technique. Besides the electronic ground state, two electronically excited states with a particularly long radiative lifetime (around 30 s and 80 s) will be used to design a variety of entangled sensor states that reject correlated noise. In this manner, the sensor state becomes insensitive to the main source for decoherence induced by fluctuations of the magnetic field environment, and the exceptionally long interrogation time of $>30$ s/ion can be fully exploited (limited only by spontaneous decay). This enables extension to a larger number ions to take advantage of the more favourable stability scaling of correlated quantum systems. Two main applications are explored with the novel quantum sensor: magnetic field gradiometry with a high spatial resolution and robust clock spectroscopy with a stability scaling that improves upon classical atomic clocks.

For the experimental realization Ba$^+$ ions will be trapped in a radiofrequency ion trap. High-fidelity single-qubit gate operation (> 99.9%) will be implemented based on the two narrow clock transitions in Ba$^+$. Techniques will be implemented to realise ground state cooling and single-ion addressing for scalability of the sensor.

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

Fri, 31 Mar 2023 00:00:00 +0000

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.

Robust quantum metrology in trapped Ba$^+$ ions to search for new physics

Fri, 31 Mar 2023 00:00:00 +0000

Summary

This project aims to develop a trapped-ion system for robust quantum metrology of entangled states. By engineering a quantum system that is insensitive to correlated noise, long coherence times can be reached to boost the measurement accuracy. These decoherence free states will be implemented in a two-ion crystal that consists of two different isotopes. In this manner, the isotope shift frequency can be extracted directly from the evolution of the entangled state. From these measurements, we will search for new ‘fifth force’ interactions between electrons and neutrons mediated by a hypothetical boson.