Simulating complex quantum systems
On a more scientific note, while I enjoyed many of the talks at the workshop, one stood out for me by far: Ignacio Cirac’s.
Briefly, Cirac talked about a bundle of new methods he and others have been developing in order to simulate quantum systems on conventional classical computers.
Doing such simulations is extremely hard in general, and there are very few quantum systems we can simulate effectively.
This failure is important. The ability to simulate classical systems numerically started in the 1930s and 1940s with the advent of computers, and it has completely revolutionized our understanding of those systems. Because of the difficulty in simulating quantum systems, we’re still effectively stuck back in about the mid-40s with those systems, except in a few special cases.
Cirac talked about the new methods he and many others are developing, based on quantum information theory, for simulating such systems. The details are complex, but the idea is pretty simple: that to do such simulations effectively, the programs must take into account both the ordinary (essentially classical) degrees of freedom, as well as the entangled degrees of freedom.
This is a simple idea, but by pushing on it, people are starting to get some spectacular results. Cirac described a slew of systems that can now be understood using these techniques, and that were previously inaccessible numerically.
It’s early days yet, but if this success continues, it’ll certainly greatly enhance our understanding of complex quantum systems, and mark what may be the first major contribution of quantum information to another field of physics.