Quantum Correlation of Microwave Two-mode Squeezed State Generated by Nonlinearity of InP HEMT

TL;DR

This paper investigates how the nonlinearity of InP HEMT transistors at cryogenic temperatures affects the quantum correlation of generated microwave two-mode squeezed states, revealing limitations in achieving high quantum discord.

Contribution

It introduces a quantum theoretical analysis of InP HEMT nonlinearity effects on microwave quantum states, highlighting the generation of mixed squeezed thermal states and the challenges in achieving high quantum discord.

Findings

Nonlinearity influences the quantum correlation in the circuit.

Generated states are mixed, not pure, due to nonlinearity.

Quantum discord can be enhanced but remains below unity at 4.2 K.

Abstract

This study significantly concentrates on cryogenic InP HEMT high-frequency circuit analysis using quantum theory to find how the transistor nonlinearity can affect the quantum correlation of the modes generated in the circuit. Firstly, the total Hamiltonian of the circuit is derived, and the dynamic equation of the motion contributed is examined using the Heisenberg-Langevin equation. Using the nonlinear Hamiltonian, some components are attached to the intrinsic internal circuit of InP HEMT to fully address the circuit characteristics. The components attached are arisen due to the nonlinearity effects. As a result, the theoretical calculations show that the states generated in the circuit are mixed, and no pure state is produced. Accordingly, the modified circuit generates the two-mode squeezed thermal state, which means one can focus on calculating the Gaussian quantum discord to evaluate quantum correlation. It is also found that the nonlinearity factors (addressed as the nonlinear components in the circuit) can intensely influence the squeezed thermal state by which the quantum discord is changed. Finally, as the primary point, it is concluded that although it is possible to enhance the quantum correlation between modes by engineering the nonlinear components; however, quantum discord greater than unity, entangled microwave photons, seems a challenging task since InP HEMT operates at 4.2 K.