Trotterless Simulation of Open Quantum Systems for NISQ Quantum Devices

The simulation of quantum systems is one of the flagship applications of near-term NISQ (noisy intermediate-scale quantum) computing devices. Efficiently simulating the rich, non-unitary dynamics of open quantum systems remains challenging on NISQ hardware. Current simulation methods for open quantum systems employ time-stepped Trotter product formulas ("Trotterization") which can scale poorly with respect to the simulation time and system dimension. Here, we propose a new simulation method based on the derivation of a Kraus operator series representation of the system. We identify a class of open quantum systems for which this method produces circuits of time-independent depth, which may serve as a desirable alternative to Trotterization, especially on NISQ devices.