First-generation atomic quantum sensors underpin a vast range of modern technologies. For example, a worldwide network of 'atomic clocks' forms the time base for the global satellite positioning systems which synchronise our communications networks and navigation services. Many of these technologies operate near the so-called Standard Quantum Limit of sensitivity. Currently there is an active effort worldwide to develop 'Quantum 2.0' technologies, which leverage some of the more exotic aspects of quantum systems to take these devices beyond their current limits.
The research programme advertised here will demonstrate new techniques for cavity-assisted quantum sensing with cold atomic vapours. By trapping the atoms within an optical ring resonator – here a triangular arrangement of extremely high-quality mirrors – the signal light will pass through the sensing medium a large number of times, vastly improving the sensitivity of the measurement. Using a gas of atoms cooled to less than one thousandth of a degree above absolute zero as a gain medium, we will build a laser which can be made to emit light into one or both of two counter-propagating directions. This will allow us to investigate the breaking of time-reversal symmetry (optical 'non-reciprocity') previously observed in our experiment. It has been predicted that non-reciprocal effects can lead to enhanced sensitivity for small signals, but experimental demonstrations are few and incomplete, and the quantum noise properties of such systems are not well understood.
In the final phase of the project, we will demonstrate new schemes for cavity-assisted magnetometry. Atomic magnetometers are used in a variety of searches for new physics beyond the Standard Model and applications in medical and bio-physics, navigation, archaeology, and civil engineering. Our approach will again be focused on exploiting the enhanced interaction between cold atoms and light within the optical cavity. Our ability to reach the collective strong coupling regime of light-matter interactions will allow us to detect very small changes in the refractive index of the atomic vapour, which will impose an amplitude modulation on the transmitted light at a frequency proportional to the magnetic field strength. By incorporating lasing as described above, the signal power can be increased, giving a corresponding improvement in the sensitivity.
This is primarily an experimental project, although the applicant should be comfortable with the theory of quantum and atomic systems. The applicant should be highly motivated and have completed (or be about to complete) a first-class undergraduate degree in Physics or the equivalent. Female applicants are particularly encouraged to apply.
For more details about the project, the funding available, advice on making your application or any other informal enquiries, please contact Dr Jon Goldwin ([Email Address Removed]). Our publications can be found at https://scholar.google.com/citations?hl=en&user=SwSe_oUAAAAJ&view_op=list_works&sortby=pubdate
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