Cavity-assisted Quantum Sensing
Lead Research Organisation:
University of Birmingham
Department Name: School of Physics and Astronomy
Abstract
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 in the UK and around the world 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. One strand of this effort focuses on technological refinement of proven techniques, with an eye towards commercialisation and deployment in real-world settings. A second strand aims to identify new systems and techniques which could offer beyond-next-generation capabilities.
The research programme proposed here will demonstrate novel 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 less than one thousandth of a degree above absolute zero as a gain medium, we will build a cold-atom laser which can be made to emit light into one or both of two counterpropagating directions. This will allow us to investigate the apparent 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 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 project will complement the work of the National Quantum Technologies programme and help extend the UK's role as a worldwide leader in quantum science and technology.
The research programme proposed here will demonstrate novel 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 less than one thousandth of a degree above absolute zero as a gain medium, we will build a cold-atom laser which can be made to emit light into one or both of two counterpropagating directions. This will allow us to investigate the apparent 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 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 project will complement the work of the National Quantum Technologies programme and help extend the UK's role as a worldwide leader in quantum science and technology.