Investigation of the Quantum Properties of Optical Parametric Oscillators

High-precision light sources, such as lasers, are essential for many applications, including atomic clocks, GPS, quantum computing, and microwave generation. It’s becoming increasingly important to understand the fundamental limits of how stable and low noise these light sources can be. In this project, the noise properties of a special light source known as an optical parametric oscillator will be investigated using light cavities, known as microresonators, fabricated in photonic chips. The goal is to determine if the standard quantum noise limit in these light oscillators can be surpassed, which would allow for even greater precision and stability than was thought possible. Such sources will further enhance the performance of applications, such as quantum networking, in quantum information science and technology (QIST). Additionally, the project will provide for the training of undergraduate and graduate students in the important field of QIST. Members of the research team will also perform outreach to middle- and high-school students on topics in optics and quantum information processing. Coherent optical sources are a critical part of experimental atomic, molecular, and optical physics. These sources include lasers, optical parametric oscillators, and optical frequency combs. As researchers push the limits of experimental precision and complexity, understanding the ultimate quantum limits of these sources is essential. Furthermore, as experimental setups become increasingly complicated, the need for developing sources that can be made more compact, robust, and scalable in number is becoming acute. In this proposal, the quantum-noise properties of optical parametric oscillators and optical frequency combs generated in microresonators will be investigated. The goal will be to significantly improve the performance of such oscillators by manipulating the input vacuum noise reservoir to achieve phase noise and frequency linewidths that are well below the standard quantum limits (i.e., the Schawlow-Townes limit). Various designs and regimes will be explored, which will be enabled through the use of integrated photonics. The vacuum squeezing elements, filters, and optical oscillator devices will all be integrated on a photonic chip. This will reduce the potential losses, make the system robust to environmental perturbations, and enable noise performance that surpasses what can be achieved with conventional sources. Ultimately, these parametric oscillators could be used for a wide variety of measurements and control for atomic and molecular systems that include precision measurement, spectroscopy, time-and-frequency metrology, ultralow-noise microwave generation, and quantum information science. 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.