RUI: Multimode Quantum State Tomography of Stored Photons

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Quantum information can be transferred from a beam of light to a cloud of atoms and controllably released at a later time. This process forms the basis of many important quantum memory devices that are fundamental to the future of quantum information science, quantum computing, and quantum communication. Prior experiments have stored light in a variety of systems, including cold atom clouds, warm atomic vapor, solid state materials, and optical fibers. To extend these successful investigations, the goal of this program is to carry out a full characterization of the quantum states of stored-and-retrieved multimode light.Dr. Dawes at Pacific University applies techniques developed for quantum state reconstruction to experimental stored-light systems. The result is a more complete understanding of the quantum state of light before and after storage. Prior detection schemes cannot distinguish between losses in the retrieval process and losses in the detection process. In particular, single-mode detection suffers from losses if the spatial mode chosen by the detector differs from the spatial mode carrying the retrieved light. Array detectors measure all spatial modes simultaneously. This capability can be used to maximize the number of retrieved photons and allows for computation and optimization of the retrieved spatial mode. Array detection therefore recovers more information on the quantum state of light than previous methods. Array detection is also used to compare multiple retrieved modes, and to explore correlations between modes. The importance of this new information is that it reveals fundamental properties of the quantum memory process.The scientific promise of this project is that it will create a new understanding of stored light processes based on the characterization of stored quantum states. Since these processes are fundamental to quantum memory devices, devices which are widely studied, this promise is of considerable value. Results from these studies in atomic vapor systems will inform future research in multimode quantum memories using solid state materials. But more than the immediate advances in the research arena, this program also trains undergraduates and inspires them to consider careers in science. Undergraduate researchers participate in every step of the project, and gain experience with experiment design, data collection, analysis, and dissemination. The technical skills acquired during this experience, combined with attentive mentoring in a supportive research community, create the best form of scientific incubator to prepare students for successful science careers. Attendance and presentations at regional and national conferences provide students with further insight into the scientific profession, as well as an opportunity to expand their network of peers. Additionally, students participate in a new five-school consortium of atomic, molecular, and optical physics research groups in the Pacific Northwest.