➀ GPS reliance issues highlighted, including signal blockage and intentional interference. ➁ Quantum inertial measurement units proposed as a solution, though currently impractical due to size and cost. ➂ Sandia National Laboratories developing compact atom interferometers using Photonic Integrated Circuits (PICs). ➃ PICs enhance system compactness, durability, and resistance to vibrations and shocks. ➄ Silicon photonic modulators developed to control light and reduce sidebands, improving system performance.