CAREER: Ultrafast Quantum Networks: Pushing the Limits of Photon Production

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

Quantum networks relying on single photons to carry information are poised to enable a new generation of secure communication, efficient computing, and high-precision sensing technologies. However, transmitting each quantum bit requires generating many single photons. As a result, the current quantum bitrates in long-range networks are often in the kHz range and below, which is insufficient for most practical applications. This project will explore the physical limits to the speed of single-photon generation by coupling quantum emitters in nanometer-sized diamond particles to metallic structures much smaller than the wavelength of light. It will create the basic knowledge allowing quantum optical circuits to operate at practical MHz- and GHz-scale quantum bitrates and at non-cryogenic temperatures, with applications extending into classical optical communication links. The project includes a plan for developing educational modules to teach high-school and undergraduate students about quantum mechanics and the nascent quantum technology. Furthermore, the outreach activity for low-income middle-school students will increase their access to STEM content and scientific careers. The proposed research project will investigate the fundamental speed and efficiency limits of plasmon-enhanced spontaneous emission. By coupling group-IV color centers in nanodiamonds to hybrid-mode plasmonic nanostructures made from low-loss crystalline metals, the project targets three major challenges. First, coherent spontaneous emission will be achieved on the sub-picosecond timescale. Second, the hybridization of dissimilar modes in nanostructures will unlock a giant field enhancement and near-unity radiative efficiency. Third, the project will achieve on-demand emission of indistinguishable photons into on-chip waveguide modes at near-THz repetition rates and at non-cryogenic temperatures. The proposed research will transform how future quantum photonic circuits operate. By increasing the light-matter interaction rates to the THz range, the project aims to outpace GHz-scale quantum dephasing and inhomogeneous broadening. The project will address the long-standing trade-off between electromagnetic field confinement and ohmic losses in plasmonic nanostructures and unlock the potential for high-bandwidth optical communication links. The project will create basic knowledge enabling practical MHz- and GHz-scale quantum bitrates, operation at non-cryogenic temperatures, and multipartite interaction of quantum dipoles for future quantum networks. The PI will develop education modules for middle-school and high-school students and provide research opportunities for at least two undergraduate researchers per semester. 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.