Measurement-induced entanglement of two superconducting qubits

TL;DR

This paper investigates how measurement-induced entanglement of two superconducting qubits remains robust despite errors caused by multiple quanta in the resonator, enhancing understanding of quantum nondemolition schemes.

Contribution

It analyzes the impact of multiple quanta on measurement-induced entanglement and demonstrates the robustness of the scheme against such errors.

Findings

Entanglement can be generated with null measurement results even with multiple quanta present.

The scheme shows remarkable robustness against errors from additional quanta.

Analysis of the conditional Hamiltonian reveals stability of the entanglement process.

Abstract

We study the problem of two superconducting quantum qubits coupled via a resonator. If only one quanta is present in the system and the number of photons in the resonator is measured with a null result, the qubits end up in an entangled Bell state. Here we look at one source of errors in this quantum nondemolition scheme due to the presence of more than one quanta in the resonator, previous to the measurement. By analyzing the structure of the conditional Hamiltonian with arbitrary number of quanta, we show that the scheme is remarkably robust against these type of errors.