EFRI ACQUIRE: A chip-scale high-dimensional entanglement and quantum memory module for secure communications

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

A chip-scale high-dimensional entanglement and quantum memory module for secure communications Non-technical: The development of quantum communication with security guaranteed by the laws of quantum physics is one of the major benefits of nonclassical information processing. Using communication bits encoded in quantum states of single photons, called qubits, this project will improve the bandwidth and reliability of quantum communication channels. Advancing the art of quantum communication with photonic qubits is a frontier research topic because although these qubits provide security, the current technology for quantum communication has some limitations. For example, the secure-key distribution rate (akin to the number of qubits per second) and the communication distance can both be improved. These operating parameters are currently around 1 Mb/s for distances around 50 km, hence their rate-distance product is many orders-of-magnitude lower than current classical fiber network communication rates and distances. The team seeks to address this problem via a transformative multi-pronged approach: (1) encoding more bits per photon by using the time-frequency degree-of-freedom; (2) developing a chip-scale photon qubit source for higher rates, higher stability, and easier deployment; (3) developing a chip-scale photon qubit storage and release module for longer distance nonclassical communications; and (4) fundamentally new protocols and architectures for orders-of-magnitude higher secure-key rates. This multi-pronged approach is supported by the team's recent leading advances in these areas, and matched with their pedagogical training and education outreach in chip-scale nonclassical optics. They have an emphasis on women and minority graduate students in their training. Their effort spans the fields of material science, nanofabrication and silicon photonics, quantum measurements, and quantum information theory. Technical: Quantum entanglement is a fundamental resource for secure information processing and communications, and photonic hyperentanglement or high-dimensional entanglement has been specifically cited in this regard for its high data capacity and error resilience. The continuous-variable nature of time¡Vfrequency entanglement makes it an ideal candidate for efficient high-dimensional coding with minimal limitations. By storing high-dimensional entanglement in quantum memories, the range of entanglement distribution can be extended for long distance quantum communications. While significant progress has been made towards sources of high-dimensional entanglement and long-term quantum memories, major challenges remain in matching the frequencies and bandwidths of these components, integrating them on-chip, room-temperature operation, and developing the theoretical framework for how they can be exploited efficiently. The intellectual significance is to address these challenges and demonstrate a scalable cross-cutting platform towards chip-enabled unbreakable communication networks. The project has three interrelated thematic Thrusts. In Thrust 1, the team methods and approaches will develop on-chip biphoton frequency comb sources and auxiliary devices for quantum communication such as integrated lithium niobate for biphoton production and single-photon frequency conversion, microresonator structures for comb creation, electrically-pumped module, and Franson and conjugate Franson interferometers for security checks. These devices are matched in frequency and bandwidth with the ones in Thrust 2, where the team will develop solid-state rare-earth quantum memories for storage of the high-dimensional biphoton frequency comb, and room-temperature operation via phononic bandgaps and laser refrigeration. In Thrust 3, the team will develop security analyses for new quantum key distribution protocols that exploit the full potential of chip-scale biphoton frequency combs, verified in a full link performance testbed. Thrust III also examines the memories in quantum repeater architectures for distributing entanglement in quantum networks, thus extending the range of high secret-key rate quantum communication. The proposed scientific advances are coupled directly to multidisciplinary education and pedagogical training of underrepresented scientists and engineers in nanoscale quantum information sciences. The PI's interdisciplinary training crosses boundaries in electrical engineering, materials science, information theory and physics, to advance the nanoscale chip-based frontiers of quantum communications.