Researchers from various Chinese universities have explored a square-lattice architecture of superconducting transmon qubits with tunable couplings. By modulating the couplers, an effective magnetic flux can be artificially synthesized, making the system ideal for simulating two-dimensional topological physics. The large coupling ratio between the interleg and intraleg coupling strengths suggests a small circuit scale to observe the topological band. The edge state in the band gap is determined by the topological Chern number. This research could have implications for quantum error correction, quantum supremacy demonstration, and quantum chemistry simulation.
What is the Two-Dimensional Topological Effect in a Transmon Qubit Array with Tunable Couplings?
A team of researchers from various Chinese universities and institutes have investigated a square-lattice architecture of superconducting transmon qubits with interqubit interactions mediated by inductive couplers. The team suggests designing the inductive coupling between the qubit and couplers into the gradiometer form to minimize the flux noise originating from the environment.
How Does the System Work?
By periodically modulating the couplers, an Abelian gauge potential, termed effective magnetic flux, can be artificially synthesized. This makes the system an excellent platform for simulating two-dimensional topological physics. In the simplest two-dimensional model, the double or three-leg ladder, a staggered vortex-Meissner phase transition can be found in the single-particle ground state as the effective magnetic flux varies.
What are the Implications of the Large Coupling Ratio?
The large coupling ratio between the interleg and intraleg coupling strengths makes the chiral current resemble squeezed sinusoidal functions. If the row number is increased, the topological band structure anticipated at massive rows begins to occur even for a relatively small number of rows. This suggests a small circuit scale to observe the topological band.
How is the Edge State Determined?
The edge state in the band gap is determined by the topological Chern number and can be calculated through integrating the Berry curvature concerning the first Brillouin zone. The researchers also present a systematic method on how to measure the topological band structure based on time and space-domain Fourier transformation of the wave function after properly excited.
What Does this Mean for Quantum Physics?
The result offers an avenue for simulating two-dimensional topological physics on the state-of-the-art superconducting quantum chips. This research is a significant step forward in the field of quantum physics, particularly in the area of superconducting quantum circuits. The findings could affect quantum error correction, quantum supremacy demonstration, and quantum chemistry simulation.
The article titled “Two-dimensional topological effect in a transmon qubit array with tunable couplings” was published on February 4, 2024, by authors Yanjun Zhao, Yuqi Wang, Yusheng Xue, Xun-Wei Xu, Yanyang Zhang, Wu-Ming Liu, and Yuxi Liu. The article, sourced from arXiv (Cornell University), explores the two-dimensional topological effect in a transmon qubit array with tunable couplings.
