Quantum walks on a programmable two-dimensional 62-qubit superconducting processor

Area of Science:

• Quantum Computing
• Quantum Simulation
• Condensed Matter Physics

Background:

• Quantum walks are quantum analogs of classical random walks.
• They are crucial for quantum simulations, search algorithms, and universal quantum computing.
• Superconducting qubits offer a promising platform for implementing quantum dynamics.

Purpose of the Study:

• To design and fabricate a superconducting qubit array for quantum walk experiments.
• To demonstrate high-fidelity single- and two-particle quantum walks.
• To implement and study quantum interference phenomena using a Mach-Zehnder interferometer on the quantum processor.

Main Methods:

• Fabrication of an 8x8 two-dimensional square superconducting qubit array with 62 functional qubits.
• Demonstration of high-fidelity single- and two-particle quantum walks.
• Implementation of a programmable Mach-Zehnder interferometer to observe quantum interference.

Main Results:

• Successful high-fidelity execution of single- and two-particle quantum walks.
• Observation of interference fringes with single and double walkers in the Mach-Zehnder interferometer.
• Demonstration of controlled quantum interference by tuning path disorders.

Conclusions:

• The developed superconducting qubit array enables advanced quantum walk demonstrations.
• This work represents a significant step towards realizing larger-scale quantum applications on noisy intermediate-scale quantum processors.
• The high programmability facilitates complex quantum simulations and interference studies.