Quantum state preparation via engineered ancilla resetting

TL;DR

This paper investigates a quantum state preparation protocol using periodic ancilla resetting, combining theoretical analysis and numerical simulations to optimize convergence and robustness for preparing specific quantum states.

Contribution

It introduces a novel protocol employing engineered ancilla resets and analyzes its effectiveness and optimal parameters through simulations, offering advantages over existing methods.

Findings

Optimal reset times enhance convergence speed.

Ancilla entanglement is crucial for efficiency.

Protocol is resilient to noise and timing deviations.

Abstract

In this theoretical investigation, we study the effectiveness of a protocol that incorporates periodic quantum resetting to prepare ground states of frustration-free parent Hamiltonians. This protocol uses a steering Hamiltonian that enables local coupling between the system and ancillary degrees of freedom. At periodic intervals, the ancillary system is reset to its initial state. For infinitesimally short reset times, the dynamics can be approximated by a Lindbladian whose steady state is the target state. For finite reset times, however, the spin chain and the ancilla become entangled between reset operations. To evaluate the performance of the protocol, we employ Matrix Product State simulations and quantum trajectory techniques, focusing on the preparation of the spin-1 Affleck-Kennedy-Lieb-Tasaki state. Our analysis considers convergence time, fidelity, and energy evolution under different reset intervals. Our numerical results show that ancilla system entanglement is essential for faster convergence. In particular, there exists an optimal reset time at which the protocol performs best. Using a simple approximation, we provide insights into how to optimally choose the mapping operators applied to the system during the reset procedure. Furthermore, the protocol shows remarkable resilience to small deviations in reset time and dephasing noise. Our study suggests that stroboscopic maps using quantum resetting may offer advantages over alternative methods, such as quantum reservoir engineering and quantum state steering protocols, which rely on Markovian dynamics.