Improved Classical Simulation of Quantum Circuits Dominated by Clifford Gates

Area of Science:

• Quantum computing
• Classical simulation
• Quantum algorithms

Background:

• Simulating quantum circuits is computationally intensive.
• Existing methods struggle with large numbers of Clifford and T gates.
• Fault-tolerant quantum computing demonstrations often rely heavily on Clifford gates.

Purpose of the Study:

• To introduce a novel classical simulation algorithm for quantum circuits.
• To enable practical simulation of medium-sized quantum circuits dominated by Clifford gates.
• To provide a verification tool for near-term quantum computers.

Main Methods:

• Developed a new algorithm for simulating quantum circuits.
• The algorithm's runtime is polynomial in qubits and Clifford gates, but exponential in T gates.
• The exponential dependency on T gates is mild, allowing practical simulations.

Main Results:

• The algorithm successfully simulated a 40-qubit hidden shift quantum algorithm.
• Demonstrated feasibility for circuits with hundreds of Clifford gates and nearly 50 T gates.
• The simulation runtime is practical for circuits with a high proportion of Clifford gates.

Conclusions:

• The new algorithm offers a practical approach for simulating specific types of quantum circuits.
• It serves as a valuable verification tool for emerging fault-tolerant quantum computing architectures.
• This method advances the classical simulation capabilities for near-term quantum devices.