Experimental Simulation of Larger Quantum Circuits with Fewer Superconducting Qubits

Area of Science:

• Quantum Computing
• Quantum Information Science

Background:

• Near-term quantum computers, operating in the Noisy Intermediate-Scale Quantum (NISQ) era, face limitations in qubit quantity and quality.
• Hybrid quantum-classical computing architectures are the primary approach for current NISQ applications, utilizing repeated low-depth quantum circuits.
• Scaling NISQ devices to larger problems necessitates innovative techniques like quantum circuit cutting.

Purpose of the Study:

• To experimentally demonstrate a circuit-cutting method for simulating quantum circuits with many logical qubits using limited physical superconducting qubits.
• To assess the effectiveness of circuit-cutting for simulating large linear-cluster states by leveraging their inherent symmetry.

Main Methods:

• Developed and experimentally implemented a circuit-cutting technique on superconducting quantum processors.
• Exploited the symmetry properties of linear-cluster states to enable simulation of larger systems with fewer qubits.
• Simulated up to 33-qubit linear-cluster states using subcircuits with a maximum of 4 physical qubits each.

Main Results:

• Achieved an experimental fidelity bound of 0.734 for simulating a 12-qubit linear-cluster state.
• Demonstrated a 19% fidelity improvement compared to a direct implementation on the same 12-qubit processor.
• Validated the feasibility of simulating significantly larger quantum circuits with substantially fewer physical qubits.

Conclusions:

• Circuit-cutting is a viable strategy for overcoming qubit limitations in NISQ devices.
• This method allows for the simulation of complex quantum circuits with enhanced fidelity.
• The experimental demonstration provides a pathway for scaling quantum simulations on current hardware.