Pengfei Zhang

Five superconducting qubits on a chip: the stage for a performance of quantum chaos. Four qubits form the system, and the fifth acts as the environment, introducing dissipation. After a short evolution, the environment is discarded, leaving the system with an open quantum map, an operator that transforms the system's state.

Three thousand meters above sea level, a sheer cliff face. A classical climber picks a single route and crawls up step by step, often getting stuck in a local minimum: a small niche with no upward path. A quantum climber acts differently: it can leap across a canyon and land in a neighboring energy basin where the route is better.

A stone falls into a well, and the splash reaches your ears with a delay. Something similar happens to light as it leaves Earth: its oscillations become less frequent, the beam seems to 'tire.' This is gravitational redshift — a phenomenon Einstein spoke of a century ago.

A translator is working in a hall where an important meeting is taking place. He translates every sentence, but the hall is noisy: nearby conversations distract him, words get mixed up, and the meaning is lost. That is what a quantum system coupled to an environment looks like: quantum chaos usually dies out because information leaks away.

A storm in the upper atmosphere lasts a few millionths of a second. A cosmic ray, a proton or a helium nucleus, strikes air molecules, sending a swarm of particles downward. Most of them stay together, but occasionally one particle gains so much energy that it surges ahead.