CAREER: Control of Spatial Quantum Correlations for Enhanced Quantum Networks

Over the last decades there has been a tremendous increase in the information capacity of classical channels that has led to an 'information revolution' that has had profound effects in how information is processed, stored, and distributed. The ability to use the higher dimensionality of the spatial degree of freedom of quantum states of light in a long-distance quantum network can bring about an analogous revolution to the field of quantum information science by making it possible to transmit large amounts of information through a quantum channel. This CAREER project will study the use of spatial quantum correlations in entangled beams of light to provide more control over the spatial degree of freedom with the goal of making it compatible with long-distance quantum networks. This will enable new possibilities for the use of this degree of freedom in applications that range from long-distance quantum communications to quantum imaging. The research will be integrated with an educational program that seeks to develop the problem-solving skills of the undergraduate students through their active participation in research and the introduction of quantum optics experiments in the undergraduate teaching laboratories. It will also provide educational outreach opportunities for the general public through the involvement of high-school teachers from the NSF RET program in the development of didactical quantum optics demonstrations. Active efforts will be made to involve underrepresented groups, such as Native Americans, Hispanics, and women, in the research and educational programs.

The spatial degree of freedom has been recognized to hold the promise for significant impact in the field of quantum information science due to its large dimensionality. However, this promise has largely been unfulfilled due to the limited capabilities that exist in terms of the control and manipulation of this degree of freedom and its incompatibility with long-distance networks. The goal of this CAREER project is to demonstrate the compatibility of the spatial degree of freedom of quantum states of light with long-distance quantum networks. This will be done through the control of the distribution of the spatial quantum correlations present in continuous-variable (CV) entangled twin beams generated through a four-wave mixing process in a double-lambda configuration in rubidium vapor. The focus on CVs will make it possible to overcome important limitations that result from the probabilistic nature of the more commonly used discrete domain approach. In particular, CVs allow for a deterministic implementation of quantum protocols. This is particularly important for applications, such as quantum repeaters, in which the low yield rate that results from the probabilistic occurrence of events leads to impractical constraints on the apparatus. Among other things, this CAREER project will provide a source capable of generating CV entangled states of light whose distribution of spatial quantum correlations can be engineered. This will enable the use of the spatial degree of freedom in quantum information applications such as secure communications, information processing, and distributed quantum computing.

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.