Integrating Self-Initialized Local Thermalizing Lindblad Operators for Variational Quantum Algorithm with Quantum...

Area of Science:

• Quantum Computing
• Quantum Simulation
• Computational Chemistry

Background:

• Simulating quantum systems, especially molecular systems, is a key application for quantum computing.
• Modeling non-unitary dynamics of open quantum systems remains a significant challenge for current quantum computers.
• Existing methods struggle with error accumulation and resource requirements.

Purpose of the Study:

• To present a new quantum computing scheme, VQS-QJ-LTLME, for simulating open quantum systems.
• To address the challenges of simulating non-unitary dynamics and system-environment interactions.
• To develop an efficient algorithm suitable for noisy intermediate-scale quantum (NISQ) devices.

Main Methods:

• The VQS-QJ-LTLME scheme combines quantum jump Monte Carlo wave function variational evolution with local thermalizing Lindblad operators.
• It utilizes trajectory averaging to evolve the system's density matrix, enabling circuit initialization post-evolution to mitigate error accumulation.
• An efficient sampling method, No-evolution sampling (NES), is introduced to accelerate Monte Carlo sampling.

Main Results:

• The VQS-QJ-LTLME algorithm requires only logarithmic qubits (log₂(n)) and has a favorable time complexity, making it suitable for NISQ devices.
• VQS-QJ-LTLME with NES significantly reduces the number of quantum trajectories needed, with rapid classical post-processing.
• Simulations of a spin-boson model and a Fenna-Matthews-Olson system showed close agreement with classical methods.

Conclusions:

• VQS-QJ-LTLME offers an efficient and accurate method for simulating open quantum systems on current quantum hardware.
• The integration of NES enhances computational speed, making complex quantum simulations more feasible.
• This approach paves the way for advanced quantum simulations in chemistry and materials science.