Entanglement Engineering by Transmon Qubit in a Circuit QED

TL;DR

This paper explores how to engineer entanglement in a circuit QED system by manipulating the coupling between a transmon qubit and a transmission line, focusing on optimizing system parameters for enhanced quantum entanglement.

Contribution

It provides a detailed quantum mechanical analysis and design guidelines for increasing entanglement through coupling engineering in transmon-based circuit QED systems.

Findings

Increased coupling near the Josephson Junction enhances entanglement.

System coherence time and energy dispersion are controllable via coupling adjustments.

Quantum mechanical analysis supports optimized entanglement engineering.

Abstract

this study significantly emphasizes on the entanglement engineering using a transmon qubit. A transmon qubit is created with two superconducting islands coupled with two Josephson Junction embedded into a transmission line. The transmon qubit energies are manipulated through its coupling to the transmission line. The key factor here is the coupling factor between transmission line and qubit by which the quantum features of the system such as transmon decay rate, energy dispersion, and related coherence time are controlled. To complete knowledge about the design, the system is quantum mechanically analyzed and the related Hamiltonian is derived. Accordingly, the dynamics equation of motions is derived and so the energy dispersion and the coupled system coherence time are investigated. The system engineering should be established in such a way that satisfies the energy dispersion and the coherence time. However, to analyze the entanglement between modes, it needs to calculate the number of photons of the transmission lines and the transmon qubit, and also the phase sensitive cross-correlation. The important section of this study emphasizes on engineering the coupling between the transmon qubit and transmission line to enhance the entanglement. The results show that around the Josephson Junction location where the more coupling is established the more entanglement between modes is created.