Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Scientific Reports

Synchronization of two cavity-coupled qubits measured by entanglement

Tiantian Huan, Ri‐Gui Zhou, Hou Ian

Published Jul 31, 2020• 11 citations
Publisher

Abstract

Some nonlinear radiations such as superfluorescence can be understood as cooperative effects between atoms. We regard cooperative radiations as a manifested effect secondary to the intrinsic synchronization among the two-level atoms and propose the entanglement measure, concurrence, as a time-resolved measure of synchronization. Modeled on two cavity-coupled qubits, the evolved concurrence monotonically increases to a saturated level. The finite duration required for the rising to saturation coincides with the time delay characteristic to the initiation of superfluorescence, showing the role of synchronization in establishing the cooperation among the qubits. We verify concurrence to be a good measure of synchronization by comparing it with asynchronicity computed from the difference between the density matrices of the qubits. We find that the feature of time delay agrees in both measures and is determined by the coupling regimes of the cavity-qubit interaction. Specifically, synchronization is impossible in the weak coupling regime.

DOI
10.1038/s41598-020-69903-1

Related papers

Synchronization of two cavity-coupled qubits measured by entanglement

Tiantian Huan, Ri‐Gui Zhou, Hou Ian

Some nonlinear radiations such as superfluorescence can be understood as cooperative effects between atoms. We regard the cooperative radiation as a manifested effect secondary to the intrinsic synchronization among the atoms and propose a time-resolved measure of synchronization on a cavity-coupled dual-qubit system using multipartite concurrence. Comparing the variation of the concurrence over time with that of an asynchronicity measure, we find that the synchronization between the qubits features a time delay characteristic to the initiation of superfluorescent pulses. The delay coincides with the duration for the qubits to establish cooperation and emit the collective radiation, after which the concurrence monotonically increases to a stationary value while the asynchronicity dives to a steady minimum. Furthermore, the establishment of synchronization is determined by the qubit-cavity coupling strength. Asynchronicity shows that synchronization is only possible when the coupling enters strong regime and sustains to a high level when the coupling becomes ultra-strong.

arXiv:1606.07209•Jun 23, 2016•1 citation

Cooperativity of two cavity-coupled qubits: a multi-partite-entanglement approach

Tiantian Huan, Hou Ian

Some nonlinear radiations such as superfluorescence can be understood as cooperative effects between atoms. We regard the cooperative radiation as a manifested effect secondary to the intrinsic cooperativity among the atoms and propose a time-resolved measure of cooperativity on a cavity-coupled dual-qubit system using multi-partite concurrence measures. We find that the cooperativity features a time delay characterisitic to superfluorescent pulses in its evolution, which coincides with the duration for the qubits to synchronize with each other. Thereafter, the cooperativity monotonically increases to a stationary value while the measure of asynchronicity dives to a steady minimum. Furthermore, the asynchronicity experiences a continuous transition to nonzero values when the coupling strength crosses from the weak to the strong coupling regime.

•Jun 23, 2016•0 citations

Direct Measurement of Atomic Entanglement via Cavity Photon Statistics

Nilakantha Meher, Mishkatul Bhattacharya, Anand K. Jha

Abstract An experimental scheme for the measurement of entanglement between two two‐level atoms is proposed. This scheme requires one of the two entangled atoms to interact with a cavity field dispersively, and it is shown that by measuring the zero time‐delay second‐order coherence function of the cavity field, one can measure the concurrence of an arbitrary Bell‐like atomic two‐qubit state. As this scheme requires only one of the atoms to interact with the measured cavity, the entanglement quantification becomes independent of the location of the other atom. Therefore, this scheme can have important implications for entanglement quantification in distributed quantum systems.

arXiv:2204.03891•Annalen der Physik•May 4, 2022•1 citation

Qubit optical-cavity interaction and quantum synchronization of two qubits inside an optical lattice

Mohamed Barhoumi, Riccardo Bassoli, Frank H. P. Fitzek

Atom-cavity interconnected systems offer an outstanding possibility for experiments in quantum computing and quantum information. Investigating the interaction between different light fields and atoms in a cavity is a vital study area of quantum optics. In this paper, we investigate the interaction between an atom(qubit) and the cavity. The Jaynes-Cummings approach is used to determine the probability of the cavity and qubit into bad and good regimes. Moreover, we examine the Wigner-functions of the cavity depending on the coupling strength. It is possible to synchronize atoms to create extremely precise atomic clocks, which might revolutionize several sectors, including navigation, communications, and scientific study. We show that the synchronization of two qubits inside an optical lattice can be accomplished using the driven Tavis-Cummings Hamiltonian. In this framework, we employ sixteen photons and show that the best quantum synchronization can be achieved between two qubits 𝑞1 and 𝑞2 in a weak regime.

Materials Science and Engineering B•Nov 20, 2024•6 citations

Dynamics of quantum correlations and linear entropy in a multi-qubit-cavity system

Alexandra Olaya-Castro, Neil F. Johnson, Luis Quiroga

We present a theoretical study of the relationship between entanglement and entropy in multi-qubit quantum optical systems. Specifically we investigate quantitative relations between the concurrence and linear entropy for a two-qubit mixed system, implemented as two two-level atoms interacting with a single-mode cavity field. The dynamical evolutions of the entanglement and entropy are controlled via time-dependent cavity–atom couplings. Our theoretical findings lead us to propose an alternative measure of entanglement, which could be used to develop a much needed correlation measure for more general multi-partite quantum systems.

arXiv:quant-ph/0311181•Journal of Optics B Quantum and Semiclassical Optics•Jul 28, 2004•15 citations

The meaning of the concurrence obtained from time-integrated two-photon density matrices in the biexciton cascade in quantum dots coupled to microcavities

Moritz Cygorek, Tim Seidelmann, F. Ungar +3 more

While, theoretically, the degree of entanglement of a two-qubit state can be quantified by the concurrence, the experimental determination of a two-qubit state, such as via quantum state tomography of the two-photon state generated by the biexciton cascade in a quantum dot, typically involves the summation of many data points corresponding to a time integration. In the prevalent literature on the biexciton cascade in quantum dots, it is therefore common to define the concurrence in terms of single- or double-time-integrated two-time correlation functions. Here, we compare the behavior of the concurrence according to the different definitions found in the literature and study the relation between the time-integrated concurrences and the actual degree of entanglement of the two-photon states generated by the biexciton cascade in a quantum dot embedded in a microcavity. We focus mainly on the often-discussed situation of a dot with finite biexciton binding energy in a cavity tuned to the two-photon resonance. Analytic and numerical calculations reveal that in this case the single-time-integrated concurrence indeed agrees well with the typical value of the concurrence according to its original definition, even when the interaction between the quantum dot and longitudinal acoustic phonons is taken into account. However, the double-time-integrated concurrence shows completely different trends with respect to changes in the exciton fine structure splitting or the cavity loss rate and should not be interpreted as a measure for the degree of entanglement.

•Dec 7, 2017•0 citations
Some nonlinear radiations such as superfluorescence can be understood as cooperative effects between atoms. We regard cooperative radiations as a manifested effect secondary to the intrinsic synchronization among the two-level atoms and propose the entanglement measure, concurrence, as a time-resolved measure of synchronization. Modeled on two cavity-coupled qubits, the evolved concurrence monotonically increases to a saturated level. The finite duration required for the rising to saturation coincides with the time delay characteristic to the initiation of superfluorescence, showing the role of synchronization in establishing the cooperation among the qubits. We verify concurrence to be a good measure of synchronization by comparing it with asynchronicity computed from the difference between the density matrices of the qubits. We find that the feature of time delay agrees in both measures and is determined by the coupling regimes of the cavity-qubit interaction. Specifically, synchronization is impossible in the weak coupling regime.
Some nonlinear radiations such as superfluorescence can be understood as cooperative effects between atoms. We regard the cooperative radiation as a manifested effect secondary to the intrinsic synchronization among the atoms and propose a time-resolved measure of synchronization on a cavity-coupled dual-qubit system using multipartite concurrence. Comparing the variation of the concurrence over time with that of an asynchronicity measure, we find that the synchronization between the qubits features a time delay characteristic to the initiation of superfluorescent pulses. The delay coincides with the duration for the qubits to establish cooperation and emit the collective radiation, after which the concurrence monotonically increases to a stationary value while the asynchronicity dives to a steady minimum. Furthermore, the establishment of synchronization is determined by the qubit-cavity coupling strength. Asynchronicity shows that synchronization is only possible when the coupling enters strong regime and sustains to a high level when the coupling becomes ultra-strong.
Some nonlinear radiations such as superfluorescence can be understood as cooperative effects between atoms. We regard the cooperative radiation as a manifested effect secondary to the intrinsic cooperativity among the atoms and propose a time-resolved measure of cooperativity on a cavity-coupled dual-qubit system using multi-partite concurrence measures. We find that the cooperativity features a time delay characterisitic to superfluorescent pulses in its evolution, which coincides with the duration for the qubits to synchronize with each other. Thereafter, the cooperativity monotonically increases to a stationary value while the measure of asynchronicity dives to a steady minimum. Furthermore, the asynchronicity experiences a continuous transition to nonzero values when the coupling strength crosses from the weak to the strong coupling regime.
Abstract An experimental scheme for the measurement of entanglement between two two‐level atoms is proposed. This scheme requires one of the two entangled atoms to interact with a cavity field dispersively, and it is shown that by measuring the zero time‐delay second‐order coherence function of the cavity field, one can measure the concurrence of an arbitrary Bell‐like atomic two‐qubit state. As this scheme requires only one of the atoms to interact with the measured cavity, the entanglement quantification becomes independent of the location of the other atom. Therefore, this scheme can have important implications for entanglement quantification in distributed quantum systems.
Atom-cavity interconnected systems offer an outstanding possibility for experiments in quantum computing and quantum information. Investigating the interaction between different light fields and atoms in a cavity is a vital study area of quantum optics. In this paper, we investigate the interaction between an atom(qubit) and the cavity. The Jaynes-Cummings approach is used to determine the probability of the cavity and qubit into bad and good regimes. Moreover, we examine the Wigner-functions of the cavity depending on the coupling strength. It is possible to synchronize atoms to create extremely precise atomic clocks, which might revolutionize several sectors, including navigation, communications, and scientific study. We show that the synchronization of two qubits inside an optical lattice can be accomplished using the driven Tavis-Cummings Hamiltonian. In this framework, we employ sixteen photons and show that the best quantum synchronization can be achieved between two qubits 𝑞1 and 𝑞2 in a weak regime.
We present a theoretical study of the relationship between entanglement and entropy in multi-qubit quantum optical systems. Specifically we investigate quantitative relations between the concurrence and linear entropy for a two-qubit mixed system, implemented as two two-level atoms interacting with a single-mode cavity field. The dynamical evolutions of the entanglement and entropy are controlled via time-dependent cavity–atom couplings. Our theoretical findings lead us to propose an alternative measure of entanglement, which could be used to develop a much needed correlation measure for more general multi-partite quantum systems.
While, theoretically, the degree of entanglement of a two-qubit state can be quantified by the concurrence, the experimental determination of a two-qubit state, such as via quantum state tomography of the two-photon state generated by the biexciton cascade in a quantum dot, typically involves the summation of many data points corresponding to a time integration. In the prevalent literature on the biexciton cascade in quantum dots, it is therefore common to define the concurrence in terms of single- or double-time-integrated two-time correlation functions. Here, we compare the behavior of the concurrence according to the different definitions found in the literature and study the relation between the time-integrated concurrences and the actual degree of entanglement of the two-photon states generated by the biexciton cascade in a quantum dot embedded in a microcavity. We focus mainly on the often-discussed situation of a dot with finite biexciton binding energy in a cavity tuned to the two-photon resonance. Analytic and numerical calculations reveal that in this case the single-time-integrated concurrence indeed agrees well with the typical value of the concurrence according to its original definition, even when the interaction between the quantum dot and longitudinal acoustic phonons is taken into account. However, the double-time-integrated concurrence shows completely different trends with respect to changes in the exciton fine structure splitting or the cavity loss rate and should not be interpreted as a measure for the degree of entanglement.