UNM Department of Physics & Astronomy Associate Professor Francisco Elohim Becerra was recently awarded an $800,000 research grant for a research project titled, "Nonclassical atomic spin ensembles based on coherent feedback and quantum eraser." This is a Department of Defense Research and Education Program for Historically Black Colleges and Universities and Minority-Serving Institutions (HBCU/MI) Grant.
“This grant allows us to study fundamental questions about the interaction of light and matter, and further our understanding of the capabilities of atomic systems for building metrological technologies with performances that go beyond conventional sensors,” said Becerra. “For UNM, this grant will enhance capacity in quantum information sciences, a field that is expected to have a large technological impact in the near future. It will support experimental research in quantum information that will complement well-established theoretical work in quantum information at UNM.”
The Quantum Optics team at UNM will utilize quantum eraser protocols to generate collective atomic states with strong quantum correlations of cold cesium atoms, such as spin-squeezed states. These states can be used for building atomic quantum sensors whose sensitivities go far beyond the limits of current sensing techniques.
In quantum eraser protocols, the entanglement carried by the light generated from its interaction with atoms is transferred back to the atoms to some degree via a second interaction. Any information left in the light about the atoms can be completely erased by measurement-based feedback. This procedure, termed quantum eraser, can in principle produce an exponential growth in the level of squeezing, which substantially enhances the sensitivity of atomic sensors.
"The fact that light and matter are discrete (quantized) in photons and atoms, means that light and matter have quantum noise fluctuations. This noise is always present in physical systems, and it is what limits many technologies," Becerra said. "Squeezing is the possibility of reducing this quantum noise in some property of the system below what is possible with uncorrelated, independent systems, at the expense of increasing noise in another property. This reduction in quantum noise can be used to build very precise measurement devices for diverse applications."
Spin squeezing can have a large impact on metrological technologies such as atomic-based sensors for atomic clocks, inertial sensors, magnetometers, and gravimeters. These sensors are highly precise, but precision is limited by the intrinsic quantum noise always present in sensors using many atoms to increase signal to noise.
For instance, current atomic clocks use the fundamental separation between two hyperfine energy levels in the ground state of cesium atoms to define the second as the duration of a given number of oscillations in this transition, just limited to the intrinsic atomic spin quantum noise. Spin squeezing can further improve the precision of these and other atomic sensors.
This project builds on the expertise in the Quantum Optics Laboratory at UNM in quantum measurements with measurement-based feedback, and Atomic Physics with cold atoms for quantum memories, entanglement generation, and quantum metrology.
"Nonclassical atomic spin ensembles based on coherent feedback and quantum eraser," said Becerra. "The project will use laser-cooled atoms and their interaction with light to generate collective atomic states with strong quantum correlations, such as spin-squeezed states. This work will build on theoretical work using a 'quantum eraser' technique to build correlations among atoms.
"The main idea is that the entanglement carried by the light generated from its interaction with atoms is transferred back to the atoms to some degree via a second interaction. Any information left in the light about the atoms can be completely erased by measurement-based feedback. This procedure, termed quantum eraser, can enhance the correlations among atoms and the level of squeezing, which substantially enhances the sensitivity of atomic sensors," he added.
The Quantum Optics group performs research focusing on the study of the quantum properties of light and matter for optimal methods of measurement, information transfer, and communications. "We are interested in the study of measurements with sensitivities beyond conventional limits of detection for communication and metrology, and the study of quantum-state superpositions from the interaction of light and matter for quantum information processing," said Becerra. "We are part of the Center for Quantum Information and Control (CQuIC) at The University of New Mexico with collaborations spanning quantum information, quantum networking, and microscopy and biology."