Periodic Reporting for period 1 - NOVUS (Nonlinear Optomechanics for Verification, Utility and Sensing)
Reporting period: 2021-08-01 to 2023-07-31
Context and Problem Addressed:
The project addresses a fundamental challenge in quantum optomechanics: the lack of analytical models that realistically capture the nonlinear dynamics and environmental interactions of quantum optomechanical systems (QOMSs). Present approaches are limited in their ability to model nonlinearities under strong optical drives and realistic noise conditions, which severely restricts both theoretical understanding and experimental design of next-generation quantum sensors.
Why It Matters for Society:
Quantum optomechanical systems have emerged as powerful candidates for ultra-sensitive measurements of weak forces, including gravitational effects and potential physics beyond the Standard Model. Enhancing our ability to model and control these systems has far-reaching implications, including improving gravimetric and gravitational wave sensing, developing quantum-enhanced force sensors, and probing fundamental aspects of nature such as quantum gravity and potential fifth forces. These advancements can impact precision measurement technologies, aid the search for new physics, and contribute to a better understanding of the quantum-classical boundary.
Overall Objectives:
The project is structured around three major objectives:
Objective 1: Develop an analytic framework for nonlinear QOMSs that includes strong optical drive terms and a realistic model for optical and mechanical dissipation, incorporating non-Markovian effects. The resulting master equation approach will provide a new theoretical tool beyond standard Langevin-based treatments and allow for close collaboration with experimentalists to tailor the model to real-world platforms.
Objective 2: Use the developed model to explore quantum metrology applications, with a focus on gravimetry and the detection of gravitational waves. This includes deriving quantum sensitivity bounds under realistic noise conditions and proposing experimentally feasible schemes using levitated QOMSs. The objective also extends to probing deviations from Newtonian gravity, such as fifth forces and possible signatures of dark energy and dark matter.
Objective 3: Investigate how nonlinear QOMSs can be used to test quantum aspects of gravity. This includes modeling gravitationally induced decoherence using mass-dependent noise models and exploring the possibility of observing gravitational entanglement in coupled mesoscopic systems. Both paths offer potential insights into whether gravity itself must be quantized.
The project addresses a fundamental challenge in quantum optomechanics: the lack of analytical models that realistically capture the nonlinear dynamics and environmental interactions of quantum optomechanical systems (QOMSs). Present approaches are limited in their ability to model nonlinearities under strong optical drives and realistic noise conditions, which severely restricts both theoretical understanding and experimental design of next-generation quantum sensors.
Why It Matters for Society:
Quantum optomechanical systems have emerged as powerful candidates for ultra-sensitive measurements of weak forces, including gravitational effects and potential physics beyond the Standard Model. Enhancing our ability to model and control these systems has far-reaching implications, including improving gravimetric and gravitational wave sensing, developing quantum-enhanced force sensors, and probing fundamental aspects of nature such as quantum gravity and potential fifth forces. These advancements can impact precision measurement technologies, aid the search for new physics, and contribute to a better understanding of the quantum-classical boundary.
Overall Objectives:
The project is structured around three major objectives:
Objective 1: Develop an analytic framework for nonlinear QOMSs that includes strong optical drive terms and a realistic model for optical and mechanical dissipation, incorporating non-Markovian effects. The resulting master equation approach will provide a new theoretical tool beyond standard Langevin-based treatments and allow for close collaboration with experimentalists to tailor the model to real-world platforms.
Objective 2: Use the developed model to explore quantum metrology applications, with a focus on gravimetry and the detection of gravitational waves. This includes deriving quantum sensitivity bounds under realistic noise conditions and proposing experimentally feasible schemes using levitated QOMSs. The objective also extends to probing deviations from Newtonian gravity, such as fifth forces and possible signatures of dark energy and dark matter.
Objective 3: Investigate how nonlinear QOMSs can be used to test quantum aspects of gravity. This includes modeling gravitationally induced decoherence using mass-dependent noise models and exploring the possibility of observing gravitational entanglement in coupled mesoscopic systems. Both paths offer potential insights into whether gravity itself must be quantized.
Over the course of the project, progress was made in the theoretical development, application, and dissemination of results on nonlinear quantum optomechanical systems (QOMSs), their noise modeling, and their role in probing fundamental physics. Additional results were obtained for related systems. The work spans foundational theory, open-system modeling, and quantum sensing applications, resulting in a strong publication record across leading journals and preprints. Below is a summary of major activities and results, organized by thematic focus and aligned with the project objectives.
1. Development of New Theoretical Tools for Nonlinear QOMSs (Objective 1)
A core goal was to develop analytical tools capturing the complex dynamics of nonlinear optomechanical systems under realistic conditions, including strong driving and non-Markovian noise. A key step was the publication of a tutorial on a Lie-algebra decoupling method enabling solutions to otherwise intractable quantum dynamics, presented in PRX Quantum as Solving Quantum Dynamics with a Lie-Algebra Decoupling Method. The preprint Enhanced optomechanical nonlinearity through non-Markovian mechanical noise introduced a model showing noise-enhanced nonlinearity. A driven-dissipative system was also analyzed in Fast optomechanical photon blockade, revealing how a two-tone drive can optimize photon blockade.
2. Applications to Quantum Sensing and Force Detection (Objective 2)
While some theoretical results from Objective 1 took longer to mature, adjacent sensing applications were pursued. Constraining modified gravity with cavity optomechanics (NJP) showed that nonlinear QOMSs can help constrain dark energy models, albeit with sensitivity limits in large systems. The work Metrology of Gravitational Effects with Mechanical Quantum Systems provided a comprehensive overview of using mechanical quantum devices to probe gravitational fields. Sensing force gradients with cavity optomechanics while evading backaction (PRA) demonstrated backaction-evading gradiometry, though in the linear regime where most current experiments operate. Related work on Optimal quantum parametric feedback cooling (PRA) addressed state preparation methods essential for ultrasensitive measurements.
3. Exploration of Fundamental Physics and Quantum Gravity (Objective 3)
A major focus was exploring the quantum–gravity interface using nonlinear QOMSs. The invited Reviews of Modern Physics article Massive quantum systems as interfaces of quantum mechanics and gravity provided a field-defining overview, positioning QOMSs as platforms for detecting quantum gravitational effects, decoherence, and entanglement. Supporting this, the preprint Optimizing confidence in negative-partial-transpose-based entanglement criteria introduced improved methods for validating entanglement in noisy mechanical systems, a key capability for testing gravitational entanglement.
Dissemination and Exploitation of Results
The project yielded 12 peer-reviewed papers and preprints, several in collaboration with leading theoretical and experimental groups across Europe and the US. Results have been presented at international conferences and are now feeding into joint experimental projects. The developed methods are ready for adaptation to practical systems and continue to influence the broader quantum technology and fundamental physics communities.
1. Development of New Theoretical Tools for Nonlinear QOMSs (Objective 1)
A core goal was to develop analytical tools capturing the complex dynamics of nonlinear optomechanical systems under realistic conditions, including strong driving and non-Markovian noise. A key step was the publication of a tutorial on a Lie-algebra decoupling method enabling solutions to otherwise intractable quantum dynamics, presented in PRX Quantum as Solving Quantum Dynamics with a Lie-Algebra Decoupling Method. The preprint Enhanced optomechanical nonlinearity through non-Markovian mechanical noise introduced a model showing noise-enhanced nonlinearity. A driven-dissipative system was also analyzed in Fast optomechanical photon blockade, revealing how a two-tone drive can optimize photon blockade.
2. Applications to Quantum Sensing and Force Detection (Objective 2)
While some theoretical results from Objective 1 took longer to mature, adjacent sensing applications were pursued. Constraining modified gravity with cavity optomechanics (NJP) showed that nonlinear QOMSs can help constrain dark energy models, albeit with sensitivity limits in large systems. The work Metrology of Gravitational Effects with Mechanical Quantum Systems provided a comprehensive overview of using mechanical quantum devices to probe gravitational fields. Sensing force gradients with cavity optomechanics while evading backaction (PRA) demonstrated backaction-evading gradiometry, though in the linear regime where most current experiments operate. Related work on Optimal quantum parametric feedback cooling (PRA) addressed state preparation methods essential for ultrasensitive measurements.
3. Exploration of Fundamental Physics and Quantum Gravity (Objective 3)
A major focus was exploring the quantum–gravity interface using nonlinear QOMSs. The invited Reviews of Modern Physics article Massive quantum systems as interfaces of quantum mechanics and gravity provided a field-defining overview, positioning QOMSs as platforms for detecting quantum gravitational effects, decoherence, and entanglement. Supporting this, the preprint Optimizing confidence in negative-partial-transpose-based entanglement criteria introduced improved methods for validating entanglement in noisy mechanical systems, a key capability for testing gravitational entanglement.
Dissemination and Exploitation of Results
The project yielded 12 peer-reviewed papers and preprints, several in collaboration with leading theoretical and experimental groups across Europe and the US. Results have been presented at international conferences and are now feeding into joint experimental projects. The developed methods are ready for adaptation to practical systems and continue to influence the broader quantum technology and fundamental physics communities.
This project has pushed the frontier of quantum optomechanics by developing new analytic techniques for modeling nonlinear systems under realistic, noisy conditions, which had previously been difficult analytically. In particular, the application of the Lie-algebra-based approach to open-system dynamics and the integration of non-Markovian mechanical noise represent an important conceptual advance.
Expected Results Until the End of the Project:
The final phase of the project focused on consolidating the solutions and working out the final details of the solution for mechanical non-Markovian noise. The final phase also includes the publication of the review article in Reviews of Modern Physics.
Potential Impact and Societal Implications:
Quantum sensing offers a number of societal benefits: by exploiting quantum coherence and entanglement, sensors can reach sensitivity levels far beyond classical limits. This can enhance technologies ranging from navigation and seismology to fundamental physics. In particular, this project strengthens the case for using mechanical quantum systems to probe gravity, both classical and quantum aspects. The Reviews of Modern Physics article, co-authored during this project and led by the project holder, will focus the community's attention on large-mass quantum systems as testbeds for quantum gravity, potentially influencing the direction of future experimental and funding priorities.
Expected Results Until the End of the Project:
The final phase of the project focused on consolidating the solutions and working out the final details of the solution for mechanical non-Markovian noise. The final phase also includes the publication of the review article in Reviews of Modern Physics.
Potential Impact and Societal Implications:
Quantum sensing offers a number of societal benefits: by exploiting quantum coherence and entanglement, sensors can reach sensitivity levels far beyond classical limits. This can enhance technologies ranging from navigation and seismology to fundamental physics. In particular, this project strengthens the case for using mechanical quantum systems to probe gravity, both classical and quantum aspects. The Reviews of Modern Physics article, co-authored during this project and led by the project holder, will focus the community's attention on large-mass quantum systems as testbeds for quantum gravity, potentially influencing the direction of future experimental and funding priorities.