Quantum criticality and state engineering in the simulated anisotropic quantum Rabi model

TL;DR

This paper investigates quantum phase transitions and state engineering in the anisotropic quantum Rabi model using superconducting qubits, revealing universal scaling laws and enabling quantum information applications.

Contribution

It introduces a method to analyze quantum criticality in the AQRM and demonstrates state generation and gate operations with practical parameters.

Findings

Universal scaling of cumulant ratio at critical point

Generation of Schrödinger cat states in AQRM

Implementation of quantum controlled phase gates

Abstract

Promising applications of the anisotropic quantum Rabi model (AQRM) in broad parameter ranges are explored, which is realized with superconducting flux qubits simultaneously driven by two-tone time-dependent magnetic fields. Regarding the quantum phase transitions (QPTs), with assistant of fidelity susceptibility, we extract the scaling functions and the critical exponents, with which the universal scaling of the cumulant ratio is captured with rescaling of the parameters due to the anisotropy. Moreover, a fixed point of the cumulant ratio is predicted at the critical point of the AQRM. In respect to quantum information tasks, the generation of the macroscopic Schr\"{o}dinger cat states and quantum controlled phase gates are investigated in the degenerate case of the AQRM, whose performance is also investigated by numerical calculation with practical parameters. Therefore, our results pave a way to explore distinct features of the AQRM in circuit QED systems for QPTs, quantum simulations and quantum information processings.