Continuously Monitored Quantum Sensors: Smart Tools and Applications

Acquiring and interpreting data about physical processes is vital for science and technology. The targeted breakthrough of the project "Continuously Monitored Quantum Sensors: Smart Tools and Applications" (C'MON-QSENS!) is to develop tools to interpret data acquired from quantum sensors. Indeed, quantum-enhanced ultra-precise sensors are among the most disruptive quantum technologies with near-term applications in several disciplines, but with a limited reach so far. Most efforts are devoted to the measurement of static properties by single-shot or repeated measurement schemes, while many real-world applications are concerned with dynamical signals. Extracting information from time-series of data needs sensors operating in the continuously monitored regime, and here is where the interdisciplinary approach of C'MON-QSENS! emerges. We aim to develop continuously monitored hot atomic ensembles and optomechanical devices, and we pursue their application in a collaboration with leading experimentalists and theory researchers in quantum information theory, statistical inference and classical signal processing. We will create a unique synergy to close the interdisciplinary gap, so modern methods of (classical) signal processing and data inference can be incorporated within the context of quantum metrology. The result will allow advanced sensing tasks to be explicitly demonstrated in experiments. We will both gain a deeper understanding of quantum information processing in the real-time regime, and develop practical approaches to quantum sensing and interpretation of real-time signals. C'MON-QSENS! will advance the current frontiers of fundamental and applied knowledge on continuously monitored quantum systems by:

A. Constructing advanced dynamical models to allow for an accurate description of real-time quantum sensors, including relevant decoherence mechanisms, non-linearities, sources of stochastic noise, and quantum back-action resulting from continuous-time measurements.

B. Developing (i) signal processing and statistical inference techniques (Bayesian filtering, compressed sensing, sequential analysis) for highly controlled scenarios when the quantum sensor and signal dynamics can be accurately modelled, and (ii) model-free machine learning methods for real-world complex scenarios. This will advance fundamental theory on continuously monitored quantum systems and provide ultimate bounds on the performance for the relevant sensing tasks.

C. Building quantum sensors based on continuously monitored atomic vapours and optomechanical systems. We will apply the dynamical models and inference techniques to optimize the sensors' operating regimes to allow tracking of real-life signals (e.g. neuron, brain, heart, and acceleration) and validate advanced sensing tasks such as wave-form estimation, model selection and change-point/anomaly detection.

Below we discuss the impact on the areas of knowledge, society, economy and people.

Knowledge: This QuantERA project will contribute to the general knowledge within the field of Physics and the more specialized fields of quantum technology, quantum sensing and optical magnetometry. In the long run, the results of this project could also impact the fields of biomedicine, cardiology and neuroscience, as a long term goal for Jensen is to develop a novel quantum technology to be used for medical diagnostics. Jensen has already engaged in discussions with experts in cardiology and also the neuroscience community is excited about optical magnetometers as exemplified by the big interest in the topic at the recent International Conference on Biomagnetism (Biomag2018).

Society: In the long run, this project will impact the medical sector as the developed methods can potentially be used for non-invasive diagnostics of heart and brain diseases. In particular cardiology departments and people suffering from heart diseases will benefit from this project. Jensen will also create awareness of science and quantum physics amongst the general public. For example, while working at the Niels Bohr Institute in Copenhagen, Jensen has several times showed the quantum physics lab to the general public during Copenhagen Culture Nights. Jensen will engage with the public for instance by getting involved in events such as the "Wonder" family festival organized by the University of Nottingham and the "Nottingham Festival of Science and Curiosity" which has the University of Nottingham as a partner.

Economy: The methods developed in this project may in the long run lead to a novel medical device for non-invasive diagnostics heart diseases. Such a device will of course have a large economic value as there currently are no non-invasive methods for diagnosing atrial fibrillation.
Jensen will investigate the commercial potential of the optical magnetometers (based on hot atomic Cesium vapour) and the methods and techniques developed in this QuantERA proposal. Potential routes for commercialising include obtaining proof-of-concept funding for an out-of-the-lab demonstrator, engaging in partnerships with medical doctors and/or companies specializing in electromagnetic or medical instrumentation, and spinning out a start-up company.

People: Quantum Technology is recognised as an upcoming technology which will create employment and growth and training of a highly-skilled workforce who can contribute to the development of this technology is highly valuable for society. Jensen will mentor the postdoc who will be funded by this QuantERA project. Several undergraduate students will do smaller projects in the Jensen's lab and will also be trained in quantum physics and technology.