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

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE

Non-Dicke superradiance in spin systems

Vyacheslav I. Yukalov

Published Sep 26, 1997• 0 citations
Publisher

Abstract

Superradiance in spin systems is studied theoretically on the basis of a microscopic model corresponding to nuclear magnets with dipole spin interactions. The onset of pure superradiance is shown to be caused by nonsecular spin interactions. While the effective interaction of spins through the common radiation field, as well as the resonator thermal-noise field, are not able to initiate coherent self-organization resulting in superradiance.

DOI
10.1117/12.287667

Related papers

Origin of Pure Spin Superradiance

Vyacheslav I. Yukalov

The question addressed here is: What originates pure spin superradiance in a polarized spin system placed inside a resonantor? The term ``pure'' means that no initial coherence is imposed on spins, and its appearance manifests a purely self-organized collective effect. An accurate solution of evolution equations for a microscopic model is given. The results show that the resonator Nyquist noise does not play any role in starting spin superradiance, but the emergence of the latter is initiated by local spin fluctuations due to nonsecular dipole interactions.

arXiv:cond-mat/9711237•Physical Review Letters•Oct 16, 1995•51 citations

Spin superradiance versus atomic superradiance

Vyacheslav I. Yukalov

A comparative analysis is given of spin superradiance and atomic superradiance. Their similarities and distinctions are emphasized. It is shown that, despite a close analogy, these phenomena are fundamentally different. In atomic systems, superradiance is a self-organized process, in which both the initial cause, being spontaneous emission, as well as the collectivizing mechanism of their interactions through the common radiation field, are of the same physical nature. Contrary to this, in actual spin systems with dipole interactions, the latter are the major reason for spin motion. Electromagnetic spin interactions through radiation are negligible and can never produce collective effects. The possibility of realizing superradiance in molecular magnets by coupling them to a resonant circuit is discussed.

arXiv:cond-mat/0506322•Laser Physics Letters•Jan 28, 2005•13 citations

Absence of spin superradiance in resonatorless magnets

Vyacheslav I. Yukalov, Elizaveta P. Yukalova

A spin system is considered with a Hamiltonian typical of molecular magnets, having dipole-dipole interactions and a single-site magnetic anisotropy. In addition, spin interactions through the common radiation field are included. A fully quantum-mechanical derivation of the collective radiation rate is presented. An effective narrowing of the dipole-dipole attenuation, due to high spin polarization is taken into account. The influence of the radiation rate on spin dynamics is carefully analysed. It is shown that this influence is completely negligible. No noticeable collective effects, such as superradiance, can appear in molecular magnets, being caused by electromagnetic spin radiation. Spin superradiance can arise in molecular magnets only when these are coupled to a resonant electric circuit, as has been suggested earlier by one of the authors in Laser Phys. 12, 1089 (2002).

arXiv:cond-mat/0505024•Laser Physics Letters•Dec 16, 2004•17 citations

Emergence of superradiance in dissipative dipolar-coupled spin systems

Saptarshi Saha, Yeshma Ibrahim, Rangeet Bhattacharyya

Abstract In the superradiance phenomenon, a collection of non-interacting atoms exhibits collective dissipation due to interaction with a common radiation field, resulting in a non-monotonic decay profile. This work shows that the dissipative dipolar-coupled systems exhibit an identical collective dissipation aided by the nonsecular part of the dipolar coupling. We consider a simplified dipolar network where the dipolar interaction between the spin-pairs is assumed to be identical. For a suitable choice of the initial condition, the resulting dynamics requires dealing with a smaller subspace that helps extend the analysis to a larger spin network. To include the nonsecular dipolar relaxation, we use a fluctuation-regulated quantum master equation. Moreover, we find that for an ensemble of N spins, the maximum intensity of the radiation exhibits a nearly quadratic scaling (N 2), and the dipolar relaxation time follows an inverse square proportionality ( 1 / N 2 ); these two observations help characterize the emergence of superradiance. Our results agree well with the standard results of pure spin superradiance observed experimentally in various systems.

arXiv:2406.09100•Journal of Physics A Mathematical and Theoretical•Dec 12, 2024•2 citations

Computer simulation of spin superradiance

Tatyana Belozerova, Victor K. Henner, Vyacheslav I. Yukalov

Coherent effects in polarized systems of nuclear or electron spins using a microscopic model are studied, but not the Bloch equations. It is shown that the spin system in a resonance circuit can emit a coherent superradiant pulse when the system is initially in an essentially unstable state, at a time much shorter than the spin dephasing time T2 when the coupling of the system with the circuit is sufficiently strong, and at the time longer than T2 when this coupling is weak. The important role if dipole spin-spin interactions is elucidated.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•May 3, 1994•0 citations

Nuclear superradiance of the spin system

Dmitry S. Bulyanitsa, Andrey V. Druzhin, Evgeni D. Trifonov

ABSTRACT It is shown that the magnetic field local inhomogeneous, caused by the stochastic spin distribution over the volume,effects significantly on the nuclear superradiation process. Keywords: Dicke superradiance, nuclear spin system 1. INTRODUCTION The possibility of the Dicke superradiance' in the nuclear spin system, placed in the magnetic field, was explained byBlombergen and Paund in 1954.2 Experimental researches of this effect related to more later time.3'4 The theoretical explanation of this experiment, based on the solution of the Maxwell - Bloch equations system was proposed (seealso7) in works.5'6 Further development of the nuclear spin superradiance theory is contained in works.8'4 A semi-classical approach,5'6 reproducing main features of the observed effect, contained a number of artificial assumptions. In particular, observation of the single pulses regime with high values of the initial spin polarizations couldn't beexplained with taking in account of Larmor frequency scanning, that took place in the experiment. To obtain thecorrespondence with the experimental data we had to artificially select the transverse relaxation time value.In the present paper we throw out these assumptions and show that the role of additional relaxation mechanismcan play line width, caused by the local magnetic field. Here we are not pretend to give the exact description of thementioned experiment,4 but only point to the sufficiently features of the phenomenon considered.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Jan 14, 2000•0 citations
Superradiance in spin systems is studied theoretically on the basis of a microscopic model corresponding to nuclear magnets with dipole spin interactions. The onset of pure superradiance is shown to be caused by nonsecular spin interactions. While the effective interaction of spins through the common radiation field, as well as the resonator thermal-noise field, are not able to initiate coherent self-organization resulting in superradiance.
The question addressed here is: What originates pure spin superradiance in a polarized spin system placed inside a resonantor? The term ``pure'' means that no initial coherence is imposed on spins, and its appearance manifests a purely self-organized collective effect. An accurate solution of evolution equations for a microscopic model is given. The results show that the resonator Nyquist noise does not play any role in starting spin superradiance, but the emergence of the latter is initiated by local spin fluctuations due to nonsecular dipole interactions.
A comparative analysis is given of spin superradiance and atomic superradiance. Their similarities and distinctions are emphasized. It is shown that, despite a close analogy, these phenomena are fundamentally different. In atomic systems, superradiance is a self-organized process, in which both the initial cause, being spontaneous emission, as well as the collectivizing mechanism of their interactions through the common radiation field, are of the same physical nature. Contrary to this, in actual spin systems with dipole interactions, the latter are the major reason for spin motion. Electromagnetic spin interactions through radiation are negligible and can never produce collective effects. The possibility of realizing superradiance in molecular magnets by coupling them to a resonant circuit is discussed.
A spin system is considered with a Hamiltonian typical of molecular magnets, having dipole-dipole interactions and a single-site magnetic anisotropy. In addition, spin interactions through the common radiation field are included. A fully quantum-mechanical derivation of the collective radiation rate is presented. An effective narrowing of the dipole-dipole attenuation, due to high spin polarization is taken into account. The influence of the radiation rate on spin dynamics is carefully analysed. It is shown that this influence is completely negligible. No noticeable collective effects, such as superradiance, can appear in molecular magnets, being caused by electromagnetic spin radiation. Spin superradiance can arise in molecular magnets only when these are coupled to a resonant electric circuit, as has been suggested earlier by one of the authors in Laser Phys. 12, 1089 (2002).
Abstract In the superradiance phenomenon, a collection of non-interacting atoms exhibits collective dissipation due to interaction with a common radiation field, resulting in a non-monotonic decay profile. This work shows that the dissipative dipolar-coupled systems exhibit an identical collective dissipation aided by the nonsecular part of the dipolar coupling. We consider a simplified dipolar network where the dipolar interaction between the spin-pairs is assumed to be identical. For a suitable choice of the initial condition, the resulting dynamics requires dealing with a smaller subspace that helps extend the analysis to a larger spin network. To include the nonsecular dipolar relaxation, we use a fluctuation-regulated quantum master equation. Moreover, we find that for an ensemble of N spins, the maximum intensity of the radiation exhibits a nearly quadratic scaling (N 2), and the dipolar relaxation time follows an inverse square proportionality ( 1 / N 2 ); these two observations help characterize the emergence of superradiance. Our results agree well with the standard results of pure spin superradiance observed experimentally in various systems.
Coherent effects in polarized systems of nuclear or electron spins using a microscopic model are studied, but not the Bloch equations. It is shown that the spin system in a resonance circuit can emit a coherent superradiant pulse when the system is initially in an essentially unstable state, at a time much shorter than the spin dephasing time T2 when the coupling of the system with the circuit is sufficiently strong, and at the time longer than T2 when this coupling is weak. The important role if dipole spin-spin interactions is elucidated.
ABSTRACT It is shown that the magnetic field local inhomogeneous, caused by the stochastic spin distribution over the volume,effects significantly on the nuclear superradiation process. Keywords: Dicke superradiance, nuclear spin system 1. INTRODUCTION The possibility of the Dicke superradiance' in the nuclear spin system, placed in the magnetic field, was explained byBlombergen and Paund in 1954.2 Experimental researches of this effect related to more later time.3'4 The theoretical explanation of this experiment, based on the solution of the Maxwell - Bloch equations system was proposed (seealso7) in works.5'6 Further development of the nuclear spin superradiance theory is contained in works.8'4 A semi-classical approach,5'6 reproducing main features of the observed effect, contained a number of artificial assumptions. In particular, observation of the single pulses regime with high values of the initial spin polarizations couldn't beexplained with taking in account of Larmor frequency scanning, that took place in the experiment. To obtain thecorrespondence with the experimental data we had to artificially select the transverse relaxation time value.In the present paper we throw out these assumptions and show that the role of additional relaxation mechanismcan play line width, caused by the local magnetic field. Here we are not pretend to give the exact description of thementioned experiment,4 but only point to the sufficiently features of the phenomenon considered.