What company is working on fusion power?

Could you please elaborate on the company that is actively engaged in the pursuit of fusion power technology? Fusion energy has been a long-standing aspiration in the energy sector, promising clean and virtually limitless energy sources. I'm particularly interested in knowing which company is at the forefront of this groundbreaking research, and what advancements they have made so far in the quest to harness the power of the sun in a controlled and sustainable manner.