Assisted quantum simulation of open quantum systems.

Area of Science:

• Quantum Computing
• Quantum Simulation
• Computational Physics

Background:

• Universal quantum algorithms promise exponential speedups but require fault-tolerant quantum computers, which are currently unavailable.
• Noisy Intermediate-Scale Quantum (NISQ) devices are the current standard, but their limitations hinder the implementation of deep quantum circuits.

Purpose of the Study:

• To introduce a quantum-assisted quantum algorithm framework to reduce the circuit depth of universal quantum algorithms using NISQ devices.
• To develop practical quantum algorithms for simulating open quantum systems on NISQ hardware.

Main Methods:

• Developed a quantum-assisted quantum algorithm framework leveraging NISQ technology to shorten quantum circuit depth.
• Proposed two quantum-assisted algorithms for short-time evolution of open quantum systems using parameterized quantum circuits.
• Introduced a variational quantum state preparation method for efficient classical vector to quantum state loading with shallow circuits and logarithmic qubits.

Main Results:

• Successfully simulated a two-level system with an amplitude damping channel.
• Demonstrated the approach on an open version of the dissipative transverse field Ising model on two sites.
• Validated the feasibility of using NISQ devices for simulating open quantum systems with reduced circuit complexity.

Conclusions:

• Quantum-assisted quantum algorithms offer a viable path to harness quantum computation for simulating complex systems on current NISQ devices.
• The proposed methods effectively reduce the resource requirements for quantum simulations, paving the way for near-term quantum advantage in specific problems.