Exploring Parity Magnetic Effects through Experimental Simulation with Superconducting Qubits

TL;DR

This paper demonstrates the simulation of four-dimensional topological semimetal bands with tensor monopoles using superconducting qubits, revealing nontrivial topological phases and parity magnetic effects.

Contribution

It introduces a novel experimental platform using superconducting circuits to simulate 4D topological phenomena and measure associated topological invariants.

Findings

Realized 4D semimetal bands with tensor monopoles

Measured fractional second Chern number indicating topological phase transition

Simulated parity magnetic effects from the parity anomaly

Abstract

We present the successful realization of four-dimensional (4D) semimetal bands featuring tensor monopoles, achieved using superconducting quantum circuits. Our experiment involves the creation of a highly tunable diamond energy diagram with four coupled transmons, and the parametric modulation of their tunable couplers, effectively mapping momentum space to parameter space. This approach enables us to establish a 4D Dirac-like Hamiltonian with fourfold degenerate points. Moreover, we manipulate the energy of tensor monopoles by introducing an additional pump microwave field, generating effective magnetic and pseudo-electric fields and simulating topological parity magnetic effects emerging from the parity anomaly. Utilizing non-adiabatic response methods, we measure the fractional second Chern number for a Dirac valley with a varying mass term, signifying a nontrivial topological phase transition connected to a 5D Yang monopole. Our work lays the foundation for further investigations into higher-dimensional topological states of matter and enriches our comprehension of topological phenomena.