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

arXiv:2312.10938 · Physical Review A

Influence of initial states on memory effects: A study of early-time superradiance

S. C. Hou, G. Q. Shuai, X. Y. Zhang, Jin-Ke Shen, X. X. Yi

Published May 7, 2024• 4 citations
arXivHTMLPDF

Abstract

The initial states of a quantum system can significantly influence its future dynamics, especially in non-Markovian quantum processes due to the environmental memory effects. Based on a previous work of ours, we propose a method to quantify the memory effects of a non-Markovian quantum process conditioned on a particular system initial state. With this method, we analytically study the early-time memory effects of a superradiance model consisting of $N$ atoms (the system) interacting with a single-mode vacuum cavity (the environment) with two types of initial states: the Dicke states and the factorized identical states. We find that the radiation intensity are closely related to the memory effects, and correspondingly, the enhancement of memory effects (from independent radiation to collective radiation) is important for the degree of superradiance, especially for the Dicke states. Furthermore, numerical results in other regimes show that the characteristics of memory effects and superradiance in longer-time dynamics can be reflected through its early-time dynamics.

DOI
10.1103/physreva.109.053708

Related papers

From Superradiance to Superabsorption: An Exact Treatment of Non-Markovian Cooperative Radiation

Ignacio González, Ángel Rivas

We investigate the emergence of cooperative radiation phenomena in ensembles of two-level atoms coupled to a lossy resonant cavity beyond the Markovian and mean-field approximations. By deriving a complete analytical solution for the two-emitter case and employing a numerically exact method for larger ensembles, we characterize the full transition from Markovian to non-Markovian collective dynamics for systems of up to $10^3$ emitters. Our results reveal three distinct regimes: a Markovian phase exhibiting the standard superradiant burst, a non-Markovian phase featuring spontaneous superabsorption of the emitted field, and a critical regime marked by pulsed collective emission. We show that the critical spectral width separating these behaviors increases monotonically with the number of emitters, demonstrating that environmental memory effects can be enhanced by cooperativity. Finally, we find that the superradiant scaling of the peak intensity progressively degrades with increasing system size, approaching a subquadratic law in the limit of a perfect cavity. In this regime, spontaneous superabsorption emerges as a distinct manifestation of non-Markovian cooperativity.

quant-pharXiv:2601.05989•Quantum•Jan 12, 2026•0 citations

Radiation trapping effect versus superradiance in quantum simulation of light-matter interaction

S V Remizov, A A Zhukov, W. V. Pogosov +1 more

Abstract We propose a realization of two remarkable effects of Dicke physics in quantum simulation of light-matter many-body interactions with artificial quantum systems. These effects are a superradiant decay of an ensemble of qubits and the opposite radiation trapping effect. We show that both phenomena coexist in the crossover regime of a ‘moderately bad’ single-mode cavity coupled to the qubit subsystem. Depending on the type of the initial state and on the presence of multipartite entanglement in it, the dynamical features can be opposite resulting either in the superradiance or in the radiation trapping despite of the fact that the initial state contains the same number of excited qubits. The difference originates from the symmetrical or nonsymmetrical character of the initial wave function of the ensemble, which corresponds to indistinguishable or distinguishable emitters. We argue that a coexistence of both effects can be used in dynamical quantum simulators to demonstrate realization of Dicke physics, effects of multipartite quantum entanglement, as well as quantum interference and thus to deeply probe quantum nature of these artificial quantum systems.

arXiv:1909.11900•Laser Physics Letters•May 16, 2019•2 citations

Memory Effects in the Dynamics of Open Quantum Systems

Laine, Elsi-Mari

In this Thesis various aspects of memory effects in the dynamics of open quantum systems are studied. We develop a general theoretical framework for open quantum systems beyond the Markov approximation which allows us to investigate different sources of memory effects and to develop methods for harnessing them in order to realise controllable open quantum systems. \n \nIn the first part of the Thesis a characterisation of non-Markovian dynamics in terms of information flow is developed and applied to study different sources of memory effects. Namely, we study nonlocal memory effects which arise due to initial correlations between two local environments and further the memory effects induced by initial correlations between the open system and the environment. \n \nThe last part focuses on describing two all-optical experiment in which through selective preparation of the initial environment states the information flow between the system and the environment can be controlled. In the first experiment the system is driven from the Markovian to the non- Markovian regime and the degree of non-Markovianity is determined. In the second experiment we observe the nonlocal nature of the memory effects and provide a novel method to experimentally quantify frequency correlations in photonic environments via polarisation measurements.

•Aug 29, 2013•1 citation

Hyperradiance from collective behavior of coherently driven atoms

Marc-Oliver Pleinert, Joachim von Zanthier, G. S. Agarwal

The collective behavior of ensembles of atoms has been studied in-depth since the seminal paper of Dicke [R. H. Dicke, Phys. Rev. 93, 99 (1954)], where he demonstrated that a group of emitters in collective states is able to radiate with increased intensity and modified decay rates in particular directions, a phenomenon which he called superradiance. Here, we show that the fundamental setup of two atoms coupled to a single-mode cavity can be distinctly exceeding the free-space superradiant behavior, a phenomenon which we call hyperradiance. The effect is accompanied by strong quantum fluctuations and surprisingly arises for atoms radiating out-of-phase, an alleged non-ideal condition, where one expects subradiance. We are able to explain the onset of hyperradiance in a transparent way by a photon cascade taking place among manifolds of Dicke states with different photon numbers under particular out-of-phase coupling conditions. The theoretical results can be realized with current technology and thus should stimulate future experiments.

arXiv:1702.05392•Optica•Jul 5, 2017•46 citations

Effect of Initial System-Environment Correlations On Work Extraction From Open Quantum Systems

Hazhir Dolatkhah, Maryam Hadipour, Soroush Haseli

Abstract In many standard analyses of quantum thermodynamics, the system and its environment are assumed to be initially independent and free of any correlations. However, in many physical scenarios, initial system-environment correlations are unavoidable. In this work, we investigate the role of initial system-environment correlations in work extraction from open quantum systems. Furthermore, we examine the effects of these correlations and the nature of environmental dynamics on the evolution of coherence, coherence-based ergotropy, and total ergotropy. In both Markovian and non-Markovian regimes, we show that initial correlations directly influence the amount of ergotropy. We also demonstrate that in the non-Markovian regime, reducing the initial correlation enables optimal utilization of memory effects and maintains work extraction efficiency over longer time intervals. In contrast, in the Markovian regime, such correlations only accelerate the decay process without producing a revival of quantum resources; therefore, work extraction must be carried out within very short time intervals.

•Jun 4, 2026•0 citations

Enhanced quantum state swapping via environmental memory

K. Mui, Austen Couvertier, T. Yu

Environmental noise is a prevalent issue that hinders the widespread adoption of quantum technologies. Standard practice to mitigate noise involves minimizing the coupling between a quantum system and its environment, which is usually modeled in the Markovian regime. By moving slightly beyond this regime into the weak non-Markovian regime, we can achieve an effective coupling that is multiple orders of magnitude smaller by exploiting the environmental memory effect. To demonstrate this effect, we simulate state swapping in a Markovian and non-Markovian environment between two modes: a cavity mode initialized as a vacuum state and an atomic motional mode initialized as a displaced squeezed coherent state. To measure the quality of state swapping between environments, we calculate and compare their corresponding multi-mode fidelity for Gaussian states. We find that a non-Markovian environment has superior state swapping fidelity across the following parameters: mean phonon number, cavity decay rate, and vibrational frequency of the atomic motional mode. The fidelity is near-unit for a non-Markovian environment within the parameter ranges mentioned in the results. These results could enable enhanced quantum information exchange between a network and chain of cavity-atom nodes and contribute toward a more prevalent adoption of quantum technologies.

APL Quantum•Mar 1, 2025•2 citations
The initial states of a quantum system can significantly influence its future dynamics, especially in non-Markovian quantum processes due to the environmental memory effects. Based on a previous work of ours, we propose a method to quantify the memory effects of a non-Markovian quantum process conditioned on a particular system initial state. With this method, we analytically study the early-time memory effects of a superradiance model consisting of NNN atoms (the system) interacting with a single-mode vacuum cavity (the environment) with two types of initial states: the Dicke states and the factorized identical states. We find that the radiation intensity are closely related to the memory effects, and correspondingly, the enhancement of memory effects (from independent radiation to collective radiation) is important for the degree of superradiance, especially for the Dicke states. Furthermore, numerical results in other regimes show that the characteristics of memory effects and superradiance in longer-time dynamics can be reflected through its early-time dynamics.
We investigate the emergence of cooperative radiation phenomena in ensembles of two-level atoms coupled to a lossy resonant cavity beyond the Markovian and mean-field approximations. By deriving a complete analytical solution for the two-emitter case and employing a numerically exact method for larger ensembles, we characterize the full transition from Markovian to non-Markovian collective dynamics for systems of up to 10310^3103 emitters. Our results reveal three distinct regimes: a Markovian phase exhibiting the standard superradiant burst, a non-Markovian phase featuring spontaneous superabsorption of the emitted field, and a critical regime marked by pulsed collective emission. We show that the critical spectral width separating these behaviors increases monotonically with the number of emitters, demonstrating that environmental memory effects can be enhanced by cooperativity. Finally, we find that the superradiant scaling of the peak intensity progressively degrades with increasing system size, approaching a subquadratic law in the limit of a perfect cavity. In this regime, spontaneous superabsorption emerges as a distinct manifestation of non-Markovian cooperativity.
Abstract We propose a realization of two remarkable effects of Dicke physics in quantum simulation of light-matter many-body interactions with artificial quantum systems. These effects are a superradiant decay of an ensemble of qubits and the opposite radiation trapping effect. We show that both phenomena coexist in the crossover regime of a ‘moderately bad’ single-mode cavity coupled to the qubit subsystem. Depending on the type of the initial state and on the presence of multipartite entanglement in it, the dynamical features can be opposite resulting either in the superradiance or in the radiation trapping despite of the fact that the initial state contains the same number of excited qubits. The difference originates from the symmetrical or nonsymmetrical character of the initial wave function of the ensemble, which corresponds to indistinguishable or distinguishable emitters. We argue that a coexistence of both effects can be used in dynamical quantum simulators to demonstrate realization of Dicke physics, effects of multipartite quantum entanglement, as well as quantum interference and thus to deeply probe quantum nature of these artificial quantum systems.
In this Thesis various aspects of memory effects in the dynamics of open quantum systems are studied. We develop a general theoretical framework for open quantum systems beyond the Markov approximation which allows us to investigate different sources of memory effects and to develop methods for harnessing them in order to realise controllable open quantum systems. \n \nIn the first part of the Thesis a characterisation of non-Markovian dynamics in terms of information flow is developed and applied to study different sources of memory effects. Namely, we study nonlocal memory effects which arise due to initial correlations between two local environments and further the memory effects induced by initial correlations between the open system and the environment. \n \nThe last part focuses on describing two all-optical experiment in which through selective preparation of the initial environment states the information flow between the system and the environment can be controlled. In the first experiment the system is driven from the Markovian to the non- Markovian regime and the degree of non-Markovianity is determined. In the second experiment we observe the nonlocal nature of the memory effects and provide a novel method to experimentally quantify frequency correlations in photonic environments via polarisation measurements.
The collective behavior of ensembles of atoms has been studied in-depth since the seminal paper of Dicke [R. H. Dicke, Phys. Rev. 93, 99 (1954)], where he demonstrated that a group of emitters in collective states is able to radiate with increased intensity and modified decay rates in particular directions, a phenomenon which he called superradiance. Here, we show that the fundamental setup of two atoms coupled to a single-mode cavity can be distinctly exceeding the free-space superradiant behavior, a phenomenon which we call hyperradiance. The effect is accompanied by strong quantum fluctuations and surprisingly arises for atoms radiating out-of-phase, an alleged non-ideal condition, where one expects subradiance. We are able to explain the onset of hyperradiance in a transparent way by a photon cascade taking place among manifolds of Dicke states with different photon numbers under particular out-of-phase coupling conditions. The theoretical results can be realized with current technology and thus should stimulate future experiments.
Abstract In many standard analyses of quantum thermodynamics, the system and its environment are assumed to be initially independent and free of any correlations. However, in many physical scenarios, initial system-environment correlations are unavoidable. In this work, we investigate the role of initial system-environment correlations in work extraction from open quantum systems. Furthermore, we examine the effects of these correlations and the nature of environmental dynamics on the evolution of coherence, coherence-based ergotropy, and total ergotropy. In both Markovian and non-Markovian regimes, we show that initial correlations directly influence the amount of ergotropy. We also demonstrate that in the non-Markovian regime, reducing the initial correlation enables optimal utilization of memory effects and maintains work extraction efficiency over longer time intervals. In contrast, in the Markovian regime, such correlations only accelerate the decay process without producing a revival of quantum resources; therefore, work extraction must be carried out within very short time intervals.
Environmental noise is a prevalent issue that hinders the widespread adoption of quantum technologies. Standard practice to mitigate noise involves minimizing the coupling between a quantum system and its environment, which is usually modeled in the Markovian regime. By moving slightly beyond this regime into the weak non-Markovian regime, we can achieve an effective coupling that is multiple orders of magnitude smaller by exploiting the environmental memory effect. To demonstrate this effect, we simulate state swapping in a Markovian and non-Markovian environment between two modes: a cavity mode initialized as a vacuum state and an atomic motional mode initialized as a displaced squeezed coherent state. To measure the quality of state swapping between environments, we calculate and compare their corresponding multi-mode fidelity for Gaussian states. We find that a non-Markovian environment has superior state swapping fidelity across the following parameters: mean phonon number, cavity decay rate, and vibrational frequency of the atomic motional mode. The fidelity is near-unit for a non-Markovian environment within the parameter ranges mentioned in the results. These results could enable enhanced quantum information exchange between a network and chain of cavity-atom nodes and contribute toward a more prevalent adoption of quantum technologies.