An international team of researchers led by scientists from IFISC (UIB-CSIC) has published a paper in which they propose a new method to simulate the dynamics of open quantum systems. The research, published in the journal Physical Review Letters, proposes a new approach to Markovian open quantum systems from statistical physics theory and collisional models, opening the door to future quantum simulations that allow a better understanding of their behaviour.
In the field of physics, two kinds of systems can be distinguished: open and closed systems. On the one hand, closed systems are considered to be isolated from the rest of the world and their evolution is determined by their own internal dynamics. On the other hand, open systems do allow the interaction of the system itself with the environment, but this exchange of energy or information needs to be modelled. This distinction also applies to quantum systems. It is precisely this interaction between the environment and the system that makes open quantum systems more difficult to work with because of their quantum nature. However, if the environment does not retain memory of the system dynamics, the latter can be modelled with a well-known and well-defined Markovian master equation.
The paper published by the researchers proposes a new collisional model that applies known theories of statistical physics to these open quantum systems in order to simulate their interaction with the environment. That is, given a quantum system divided into several local subsystems, its dynamics can be obtained making these subsystems interact with the environment by means of several small, repeated "shocks". The paper shows that this model is fully equivalent to the well-known general master equation. In addition, they have also shown that this model can be efficiently simulated on a quantum computer.
This work is a step forward for the simulation of any kind of network modelling open Markovian quantum systems. Among the dynamics that can be efficiently simulated are, for example, problems of quantum thermodynamics, transport in complex open systems or superradiance.
Collision models can efficiently simulate any multipartite Markovian quantum dynamics. Cattaneo, Marco; De Chiara Gabriele; Maniscalco, Sabrina; Zambrini, Roberta and Giorgi, Gian Luca. Physical Review Letters 126, 130403 (1-8) (2021). DOI: 10.1103/PhysRevLett.126.130403