Describe the experimental techniques used to generate and measure entangled states, highlighting their challenges and current advancements.

Experimental techniques to generate entangled states include spontaneous parametric down-conversion in nonlinear crystals and entanglement via trapped ions or superconducting qubits. Measuring entangled states typically involves quantum state tomography and Bell test experiments. Challenges include maintaining coherence and minimizing noise, which require advanced techniques like cryogenics, ultra-high vacuum environments, and precise control of experimental parameters. Current advancements focus on improving the fidelity and scalability of entangled state generation and measurement, as well as integrating these processes into practical quantum technologies.