As much as I'd like to see a mission to Alpha Centauri that would only take 2-3 decades, there are a few significant hurdles that we are going to have to jump over. So far, the 2 main types of proposed methods of interstellar travel have been a "slow" nuclear powered ship that cruises between 0.04-0.12c and a "fast" nano-probe powered by a light sail that can reach 0.10-0.20c.

Project Daedalus was originally conceived in the 1970s as a fusion rocket that ran on deuterium/helium-3 that could travel to Barnard's star at 0.122c. The main drawback is that the amount of Helium 3 required would take roughly 20 years to mine, and the probe would not have any leftover fuel to de accelerate and would instead be a flyby mission. Due to the scarcity of helium-3 and the inability to go into orbit around any potential planets, a probe of Daedalus' design is unlikely to be viable.

Icarus Firefly was designed in 2009 and utilizes a Z-pinch fusion engine running on deuterium/deuterium, which resolves the issue of needing copious amounts of helium-3. However, it would have a maximum cruise velocity of 0.045c, and the after accounting for acceleration/de-acceleration, Firefly would arrive at Alpha Centauri roughly 100 years after it has been launched. I see this as a more viable option than Daedalus, but constructing such a probe in orbit and ensuring that it can operate for 100+ years without fail would be challenging.

Finally, we have Breakthrough Starshot, which is perhaps the most achievable out of the 3. These gram sized probes could reach Alpha Centauri in just 20-40 years, but they would be restricted to fly-bys only and need to be powered by a 100 gigawatt laser array located in space. In order to send such a mission, we would need to effectively scale down sensors, chips, etc to meet the stringent weight limits and then find a way to set up an orbital laser array. Not impossible, but still extremely difficult.