Investigating Quantum-Enhanced Metrology Using Interacting Spin Models Realized in Molecular Tweezer Arrays

Quantum mechanics sets fundamental limits on how well one can sense and measure signals in the physical world. Without quantum entanglement measurement precision is fundamentally limited to the so-called “Standard Quantum Limit” (SQL). Nevertheless, it is known that the right type of quantum entanglement in systems with many quantum particles allows one to surpass the SQL, allowing substantial improvements in precision. This idea is known as quantum-enhanced metrology, and it is a key application in the emerging field of quantum science and technology. The research team will use a new quantum platform consisting of laser-cooled molecules trapped in programmable arrays of tightly focused laser beams to explore new methods of performing quantum-enhanced metrology. In this project the research team aims to address several experimental goals: 1) Creating precise types of many-particle entanglement in interacting molecular systems useful for enhanced metrology, and 2) characterizing the robustness against real-world imperfections of certain types of metrologically useful entanglement. In addition to these specific research aims, the project will have additional potential benefits. The project will advance the state-of-the art in quantum control over ultracold molecular matter. The project will also train undergraduate, graduate, and postdoctoral researchers in the nascent field of quantum science and technology, which is a crucial part of developing a quantum-capable workforce. Quantum-enhanced metrology allows one to use many-body entangled states to improve measurement precision beyond that of the SQL. An important class of many-body states with metrologically useful entanglement are spin-squeezed states, which have been realized in a variety of quantum platforms such as trapped ions and neutral atoms. In this project, the research team aims to experimentally investigate creating spin-squeezed states in a new quantum platform--molecules. The team aims to use intrinsic electric dipolar interactions in programmable arrays of laser-cooled molecules to create spin-squeezed states of molecular matter and investigate their robustness to experimental imperfections such as spatial disorder. Specifically, the team will: 1) Explore using one-axis twisting dynamics present in XX/XXZ-type spin models to create spin-squeezing in 1D molecular chains, and 2) use microscopic spatial correlations available in the molecular tweezer platform to characterize the spin-squeezed states and their robustness to imperfections. Not only will the proposed work only open a new type of quantum matter for use in quantum-enhanced metrology, which could have potential impact both on sensing and precision measurements that search for new physics, but it could also provide insights into the fundamental properties of spin-squeezed states that are dynamically created using finite-ranged interactions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.