In this article, the author claimed that researches from Harvard and MIT created 256 qubits quantum simulator. However, we are not talking about piece of software on a classical computer but actual quantum system:
In 2017, they created a 51 qubit quantum simulator using rubidium atoms lined up in a 1D array. And now, they have created a larger 256 qubit system using atoms that can be arranged in a 2D array.
According to the article, such simulator is almost based on cold atom technology.
In another article it is stated that
“If you make systems larger and larger, very quickly you will run out of memory and computing power to simulate it on a classical computer,” he added. “The way around that is to actually build the problem with particles that follow the same rules as the system you’re simulating. That’s why we call this a quantum simulator."
So, this means that the researches created a model of a quantum system with help of another quantum system. They claimed that these quantum simulators can be also used for solving optimization problems. At the same time, quantum simulators are not universal quantum computers as gate-based ones.
Based on the description of the simulators, they seems to be similar to quantum annealers. So, my question is what kind of tasks we can solve on the simulators? Are they suitable only for Hamiltonian simulation?