Bath‐Induced Collective Phenomena on Superconducting Qubits: Synchronization, Subradiance, and Entanglement Generation

Marco Cattaneo,Sabrina Maniscalco,Gian Luca Giorgi,Gheorghe Sorin Paraoanu,Roberta Zambrini

doi:10.1002/andp.202100038

Abstract

AbstractA common environment acting on a pair of qubits gives rise to a plethora of different phenomena, such as the generation of qubit–qubit entanglement, quantum synchronization, and subradiance. Here, time‐independent figures of merit for entanglement generation, quantum synchronization, and subradiance are defined, and an extensive analytical and numerical study of their dependence on model parameters is performed. A recently proposed measure of the collectiveness of the dynamics driven by the bath is also addressed, and it is found that it almost perfectly witnesses the behavior of entanglement generation. The results show that synchronization and subradiance can be employed as reliable local signatures of an entangling common‐bath in a general scenario. Finally, an experimental implementation of the model based on two transmon qubits capacitively coupled to a common resistor is proposed, which provides a versatile quantum simulation platform of the open system in any regime.

Highlights

Superradiance, that is, the enhancement of the emission power of atoms jointly different phenomena, such as the generation of qubit–qubit entanglement, dissipating into a common environment quantum synchronization, and subradiance
Subradiance, entanglement generation, and correlations in the dynamics of decoupled qubits share a common origin in this system, namely the presence of a collective bath, they are essentially four different physical phenomena
We have investigated the behavior of quantum synchronization, subradiance, entanglement, and collectiveness of the dynamics, in a broad scenario of two superconducting transmon qubits dissipating into a common thermal bath

Summary

Introduction

Superradiance, that is, the enhancement of the emission power of atoms jointly different phenomena, such as the generation of qubit–qubit entanglement, dissipating into a common environment quantum synchronization, and subradiance. Time-independent figures of merit for entanglement generation, quantum synchronization, and subradiance are defined, and an extensive analytical and numerical study of their dependence on model parameters is performed. Speaking, we aim to investigate the collective features of the quantum map (dynamical semigroup) describing the open dynamics, or, equivalently, of the corresponding Markovian master equation.[1] We provide specific experimental prescriptions for measuring each of these figures of merit: P.O. Box 43, FI-00014 Helsinki, Finland one would need to start from different initial states, for example, S.

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Conclusion