Abstract
Investigation of strongly interacting, nonlinear quantum field theories (QFT-s) remains one of the outstanding challenges of modern physics. Here, we describe analog quantum simulators for nonlinear QFT-s using mesoscopic superconducting circuit lattices. Using the Josephson effect as the source of nonlinear interaction, we investigate generalizations of the quantum sine-Gordon model. In particular, we consider a two-field generalization, the double sine-Gordon model. In contrast to the sine-Gordon model, this model can be purely quantum integrable, when it does not admit a semi-classical description - a property that is generic to many multi-field QFT-s. The primary goal of this work is to investigate different thermodynamic properties of the double sine-Gordon model and propose experiments that can capture its subtle quantum integrability. First, we analytically compute the mass-spectrum and the ground state energy in the presence of an external `magnetic' field using Bethe ansatz and conformal perturbation theory. Second, we calculate the thermodynamic Bethe ansatz equations for the model and analyze its finite temperature properties. Third, we propose experiments to verify the theoretical predictions.
Highlights
The longstanding goal of quantum field theory (QFT) is to predict the masses of the excitations and their scattering cross-sections in terms of the parameters of the theory and to characterize the different phases and the phase-transition points
quantum electronic circuit (QEC) simulation of integrable quantum field theories (QFT-s) may be viewed as a method to benchmark these analog simulators by comparing experiments to analytical theoretical predictions
This leads to a systematic investigation of more general QFT-s, by systematically including perturbations which break integrability
Summary
The longstanding goal of quantum field theory (QFT) is to predict the masses of the excitations and their scattering cross-sections in terms of the parameters of the theory and to characterize the different phases and the phase-transition points. Little remains known about the possibility to solve the dSG model exactly, and to infer from such a solution properties of physical interest This is because, remarkably, as soon as more than one bosonic degree of freedom is involved, quantum and classical integrability often part ways. While some doubts remain on the exact nature of this statement, it is strongly believed in the community that the manifold: α12 +α22 = 4π/ is quantum integrable (in the following we will set = 1) This is, a remarkable statement: we are facing a situation where a classical soliton wave-packet, which solves the classical field equations, gets scrambled, but its quantized counterpart, when the couplings reach some magical values, propagates undistorted and scatters only with phase-shifts! It is expected that the final results can be continued to the limit where this extra boson decouples, but this assumption is dangerous in view of the singularity of this limit
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
