QII-TAQS: Quantum Photonics at Telecommunications Wavelengths Based on Metal-Ion-Doped Materials

Montana State University, Bozeman MT

Investigators

Abstract

The rapidly developing field of quantum information science exploits the unique properties of quantum states to process, store, and transmit data in new ways that are impossible to achieve with conventional information, communication, and computer technologies. For these next-generation quantum systems to be implemented in practical, real-world applications, there is a critical need to develop chip-scale integrated components that perform all the functions required for traditional information systems, but at the tremendously more demanding quantum level. While many such individual components have been demonstrated, current implementations have employed a wide variety of disparate, and often incompatible, approaches that are not easily integrated with each other or with the existing conventional technological infrastructure, such as optical fiber networks and classical computer processors. To address the need for such integration, this project brings together researchers with expertise in quantum photonics and quantum hardware fabrication at Caltech, quantum theory and semiconductor physics at Caltech, semiconductor growth and devices at University of Texas - Austin, and quantum decoherence, solid-state chemistry, and light-matter interactions at Montana State University. This interdisciplinary team seeks to develop and design integrated quantum hardware by incorporating rare-earth ions, which are one of the most successful quantum systems, with semiconductor materials that can be easily integrated with existing optical and electronic technologies. In addition to the direct impact in quantum information science, this research also provides new insights into the nanoscale properties of ions and defects in semiconductors, since the intrinsically fragile nature of quantum states can be used as a uniquely powerful probe of interactions and imperfections in materials. In turn, this information can be used to accelerate the development of ion-enabled semiconductor technologies far beyond quantum applications, such as electroluminescent devices, integrated electro-optic components, and high-speed photonic signal processing and sensing systems. Rare-earth-ions doped into complex oxides have enabled demonstrations of state-of-the-art technologies for optical quantum memories and shown excellent prospects for implementing microwave to optical quantum transduction and single quantum bits. In particular, Er3+ provides direct optical addressing at 1.5 micron telecommunications wavelengths that allows integration with existing infrastructure and commercial hardware. To enable robust, scalable quantum photonic devices based on metal-ion-doped materials, the technology would be based ideally on established semiconductor materials that are easily fabricated with conventional processes rather than the existing oxide materials that are difficult to incorporate into integrated quantum devices. This research explores the quantum optical properties of rare-earth and transition-metal ions with transitions at telecom wavelengths doped into III-V semiconductors and uses these developed materials to build a scalable nanophotonic quantum device platform. These materials show promise for combining the excellent quantum coherence properties of the metal-ion centers with the technological capabilities for growing high quality layered materials via molecular beam epitaxy and fabricating high-performance, integrated semiconductor devices. Specifically, this work investigates the low metal-ion concentration regime that has not yet been studied for semiconductors, particularly for the cryogenic temperatures employed in quantum information science where many of the traditional mechanisms that can cause relaxation are strongly suppressed. Furthermore, the optical and spin quantum coherence properties of ions such as Er3+ remain entirely unexplored in semiconductors, along with effects of materials physics unique to these host materials (charge injection, Auger relaxation, strong lattice polarization, etc.). The project addresses the critical need for scalable quantum photonic systems by closely coordinating studies and modeling of material properties and chemistry, nanoscale dynamics and decoherence phenomena, and quantum device engineering along with the discovery and fundamental study of new decoherence and interaction phenomena in this previously unexplored regime for these materials. 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.