Synchronizing Two Superconducting Qubits through a Dissipating Resonator.

Benedetto Militello,Anna Napoli

doi:10.3390/e23080998

Abstract

A system consisting of two qubits and a resonator is considered in the presence of different sources of noise, bringing to light the possibility of making the two qubits evolve in a synchronized way. A direct qubit–qubit interaction turns out to be a crucial ingredient, as well as the dissipation processes involving the resonator. The detrimental role of the local dephasing of the qubits is also taken into account.

Highlights

The complementary situation consisting of two oscillators coupled with a dissipating two-state system has been analyzed [15], and it has been brought to light that, under suitable hypotheses, the two oscillators reach an almost stationary regime where they oscillate at the same frequency, leading to their synchronization
We studied a pseudo-Dicke model describing the interaction between a harmonic oscillator and two two-state systems, which can be realized with superconducting devices
Since all the components were subjected to an interaction with the environment, dephasing and dissipation processes were included in the model

Summary

Introduction

In the realm of quantum mechanics, two-level systems have been considered, as for example the case of two interacting two-state systems undergoing dissipation, which dynamically align after a certain time [9,10], or two atoms in a cavity coupled through the relevant mode [11] In all such cases, the key ingredients to obtain synchronization are the formation of correlations (typically in the form of entanglement) and dissipation, which drives the system towards suitable superpositions of a limited number of states sharing one frequency or different frequencies, but very close ones. Superconducting devices can be fabricated using modern integrated circuit technology, and their properties, as for example their energies, can be adjusted in situ and determined by circuit parameters, allowing for implementing devices with the desired features [17] These systems offer a rich space of parameters and possible operation regimes allowing for the realization of a plethora of Hamiltonian models involving artificial atoms (including qubits as a special case) and resonators [19].

Hamiltonian and Dissipators

Conservation of the Excitation Number

Theoretical Analysis

Simulations

Dephasing

Discussion and Conclusions