Sampling Continuous Quantum Dynamics from a Single Static State

Abstract

While quantum simulation is one of the most promising applications of modern quantum devices, accessible simulation times are fundamentally limited by finite coherence times due to omnipresent noise. Based on the ideas of relational dynamics/time and of exchanging time for space resources, we propose an approach to simulating quantum dynamics under general time-dependent Hamiltonians in continuous time, which aims to overcome this limitation by encoding the full dynamics in a single static quantum state. This is achieved by introducing auxiliary qubits, which play the role of a clock, and by tailoring their dynamics and interaction with the original system. As opposed to traditional methods, no short-time propagators, or approximations thereof, are required in our framework. We outline the preparation of a static global state of system and clock via a variational quantum-classical algorithm as well as the sampling of the system's dynamics by performing projective measurements on the clock. Finally, we provide an example of our approach in terms of a driven qubit.