Leonard Susskind on Quantum Computers as Simulators

Physicist Leonard Susskind says a major potential application of quantum computers is simulating quantum systems that are hard to model classically.

He describes constructing a controllable model and measuring it, allowing researchers to vary conditions that may be difficult to change in the original system.

He suggests such simulations could help study fundamental physics as well as chemistry and materials. These are possible applications, not a guarantee that present devices can solve every such problem.

The discussion compares simulation with the well-known quantum algorithm for factoring. Susskind cautions against assuming that every computational problem will have a similar speedup.

He returns to the difficulty of classical simulation and the appeal of using controllable quantum systems as models. Practical usefulness depends on the task and the available hardware.

The speakers discuss the relationship between quantum information, physical systems and the questions researchers may investigate with future devices.

Susskind describes research connections between large quantum computers and black holes as an example of a macroscopic question in quantum physics.

Asked about brains, he says he is not a neuroscientist and reports that specialists he has spoken with generally view brain function as classical. He treats alternative ideas as uncertain.

He notes that large materials can have properties dependent on quantum effects, mentioning superconductors and topological materials as examples.

These examples illustrate why quantum tools can matter for understanding macroscopic materials made of microscopic components.