Measurement of many-body quantum correlations in superconducting circuits
Phys. Rev. B 112, 165134 – Published 23 October, 2025
DOI: https://doi.org/10.1103/1wb4-df6c
Abstract
Recent advances in superconducting circuit technology have made the fabrication of large, customizable circuits routine. This has led to applications beyond quantum information, including quantum simulation. A key challenge in this effort is the identification of the quantum states realized. Here, we propose a probe circuit capable of measuring many-body correlations in an analog quantum simulator superconducting circuit. This probe, which is specially designed for many-photon states, exploits the nonlinearity of the Josephson junction to measure two-point correlation functions of the superconducting phase operator. We demonstrate the capabilities of this design in the context of an LC-ladder with a quantum impurity. The proposed probe allows for the measurement of inherently quantum correlations, such as two-mode squeezing, and it has the potential to significantly expand the scope of analog quantum simulations using superconducting circuits.