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

Physical Review A

Spontaneous emission spectrum from a V-type artificial atom in a strong-coupling regime: Dark lines and line narrowing

Yiying Yan

Published Oct 16, 2023• 6 citations
Publisher

Abstract

We employ a time-dependent variational approach with the multiple Davydov ${D}_{2}$ ansatz and two approximate analytical methods to study the spontaneous emission of a V-type artificial atom in the strong-coupling regime, where the decay rate of the emitter becomes a considerable fraction of its transition frequencies, and focus on quantum-interference-induced effects. The variational approach is found to be accurate in certain strong-coupling regimes and is used as the benchmark to address the validity of the analytical methods: the rotating-wave approximation (RWA) and the transformed RWA (TRWA). It is found that the TRWA is fairly accurate in the strong-coupling regime where the RWA breaks down. By using the numerical and analytical methods, we illustrate that there are dark lines and line narrowing in the emission spectra in the strong-coupling regime and in a wide accessible range of the emitter parameters. We also illustrate how the emission spectrum is altered by the counter-rotating couplings. The present results offer insights into the experimental observation of the quantum-interference-induced effect in the strong-coupling regime and in the context of artificial atoms.

DOI
10.1103/physreva.108.043712

Related papers

Controllable spontaneous emission spectrum in an artificial giant atom: Dark lines and bound states

Yiying Yan, Zhiguo Lü

We study the spontaneous emission spectra of a few-level giant atom strongly coupled to a one-dimensional waveguide by employing variational and analytical approaches, which are beyond the rotating-wave approximation and the Markovian approximation. We show that the interference effects due to the multiple coupling points result in dark lines in spontaneous emission spectra of either two-level or three-level giant atoms regardless of whether there is a bound state or not. We illustrate that the generation of dark lines depends on the distance between the coupling points and their number. In the absence of a bound state, the dark lines can be used to suppress emission at a certain frequency in the spectrum. In the presence of a bound state, the total intensity of the emission spectrum can be significantly suppressed. The present results offer the possibility of control over the spontaneous emission with the dark lines due to the destructive interference in giant atoms. Published by the American Physical Society 2024

Physical Review Research•Mar 19, 2024•12 citations

Distance-dependent emission spectrum from two qubits in a strong-coupling regime

Rongzhen Hu, JunYan Luo, Yiying Yan

We study the emission spectrum of two distant qubits strongly coupled to a waveguide by using the numerical and analytical approaches, which are beyond the Markovian approximation and the rotating-wave approximation. The numerical approach combines the Dirac-Frenkel time-dependent variational principle with the multiple Davydov ${D}_{1}$ ansatz. A transformed rotating-wave approximation (TRWA) treatment and a standard perturbation (SP) are used to analytically calculate the emission spectrum. It is found that the variational approach and the TRWA treatment yield accurate emission spectra of the two distant qubits in certain strong-coupling regimes while the SP breaks down. The emission spectrum is found to be asymmetric irrespective of the two-qubit distance and exhibits a single peak, double peaks, and multiple peaks depending on the two-qubit distance as well as the initial states. In sharp contrast with the single-qubit case, the excited-state populations of the two qubits can ultraslowly decay due to the subradiance even in the presence of a strong qubit-waveguide coupling, which in turn yields an ultranarrow emission line. Our results provide insights into the emission spectral features of the two distant qubits in the strong light-matter coupling regime.

arXiv:2304.11103•Physical Review A•Aug 7, 2023•3 citations

Variational approach to time-dependent fluorescence of a driven qubit

Yiying Yan, Lipeng Chen, JunYan Luo +1 more

We employ the Dirac-Frenkel variational principle and the multiple Davydov ansatz to study time-dependent fluorescence spectra of a driven qubit in the weak to strong qubit-reservoir coupling regimes, where both the Rabi frequency and the spontaneous decay rate are comparable to the transition frequency of the qubit. Our method agrees well with the time-local master-equation approach in the weak coupling regime, and offers a flexible way to compute the spectra from the bosonic dynamics instead of two-time correlation functions. While the perturbative master equation breaks down in the strong coupling regime, our method actually becomes more accurate due to the use of bosonic coherent states under certain conditions. We show that the counter-rotating coupling between the qubit and the reservoir has considerable contributions to the photon number dynamics and the spectra under strong driving conditions even when the coupling is moderately weak. The time-dependent spectra are found to be generally asymmetric, a feature that is derived from photon number dynamics. In addition, it is shown that the spectral profiles can be dramatically different from the Mollow triplet due to strong dissipation and/or multiphoton processes associated with the strong driving. Our formalism provides a unique perspective to interpret time-dependent spectra.

arXiv:2008.09726•Physical Review A•Aug 21, 2020•15 citations

Characteristics of spontaneous emission from a two-level atom in a very high Q cavity

Xiang Chen, Mi Xian-Wu

In this paper we investigate a coupled system of an initially excited two-level atom coupled to a monomode cavity,and compute spontaneous emission spectrum and mean population density emitted by the atom and the cavity using the quantum theory that accounts for theoretical derviation and numerical calculation.The spectra emitted separately by the atom and the cavity in of strong coupling region are dramatically different from those in weak coupling region at resonance.The cavity spectrum line splitting in the strong coupling region,however,a hole exists in the atomic spectrum in the weak coupling region.We study systematically the emission spectra when the atom and the cavity are detuned,and the results show that if the cavity linewidth is much smaller than the atomic linewidth(good cavity regime),photons are emitted at the cavity frequency even if the atom and the cavity are strongly detuned,and provide theoretic foundation for the apparently puzzling feature observed in the recent experiment.In this paper we computate the atomic and the cavity mean population densities each as a function of time and their relation to the luminous intensity, and offer a new insight into civity induced transparency effect.

Acta Physica Sinica•Jan 1, 2011•2 citations

Control of the spontaneous emission spectrum in a drivenN-type atom by dynamically induced quantum interference

Bibhas Kumar Dutta, P.K. Mahapatra

The modification of the spontaneous emission spectrum has been studied in this paper in a four-level doubly driven N-type atomic system. In the presence of two coherent fields, emphasis has been given to studying the spectral distribution of spontaneous emission in the relaxation process of the initially prepared excited level. The phenomenon of quantum interference dynamically induced in the system by these fields can significantly change the spontaneous emission spectrum. We have shown the emergence of a two-peak spectrum where two widely separated symmetric peaks are associated with a sharp dark line at their mid-position. At different dynamic conditions, we have also shown that two symmetric peaks may appear in the spectrum with an extended dark zone between them. Depending on the values of the Rabi frequencies and the detunings of the external fields, one can achieve a large enhancement of very narrow spectral components within the spontaneous emission line shape under different conditions. The phenomenon of suppression of spectral line and the selective cancellation of spontaneous emission have also been discussed. The results shown in various cases are analysed by considering all possible dressed states corresponding to the bare state model. The influence of collision-induced effects on the spontaneous emission spectrum is investigated as a conditional case.

Physica Scripta•May 21, 2009•9 citations

Quantum-mechanical interference effects in the spontaneous-emission spectrum of a driven atom

Shi-Yao Zhu, Lorenzo M. Narducci, Marlan O. Scully

We study the influence of quantum interference on the spontaneous emission from an excited two-level atom when either the atomic upper or lower level is coupled by a coherent field to a third, usually higher-lying, state. In the case of the upper level coupling, destructive quantum interference between two competing decay amplitudes produces a dark line in the emission spectrum, a phenomenon that should not be confused with the well known population trapping, and a narrowing of one of the two side lobes that make up the spectral profile. Quantum interference is absent, instead, in the case of the lower level coupling, and the spectrum modified by the external driving field is just the incoherent superposition of two Lorentzian lines. We suggest a physical interpretation of these results. In addition, we compare the analytic predictions of the simplest nontrivial versions of these models with more realistic but nonanalytic descriptions and show, numerically, that the interference effects persist in the upper level case even when additional complications are taken into account.

Physical Review A•Dec 1, 1995•164 citations
We employ a time-dependent variational approach with the multiple Davydov D2{D}_{2}D2​ ansatz and two approximate analytical methods to study the spontaneous emission of a V-type artificial atom in the strong-coupling regime, where the decay rate of the emitter becomes a considerable fraction of its transition frequencies, and focus on quantum-interference-induced effects. The variational approach is found to be accurate in certain strong-coupling regimes and is used as the benchmark to address the validity of the analytical methods: the rotating-wave approximation (RWA) and the transformed RWA (TRWA). It is found that the TRWA is fairly accurate in the strong-coupling regime where the RWA breaks down. By using the numerical and analytical methods, we illustrate that there are dark lines and line narrowing in the emission spectra in the strong-coupling regime and in a wide accessible range of the emitter parameters. We also illustrate how the emission spectrum is altered by the counter-rotating couplings. The present results offer insights into the experimental observation of the quantum-interference-induced effect in the strong-coupling regime and in the context of artificial atoms.
We study the spontaneous emission spectra of a few-level giant atom strongly coupled to a one-dimensional waveguide by employing variational and analytical approaches, which are beyond the rotating-wave approximation and the Markovian approximation. We show that the interference effects due to the multiple coupling points result in dark lines in spontaneous emission spectra of either two-level or three-level giant atoms regardless of whether there is a bound state or not. We illustrate that the generation of dark lines depends on the distance between the coupling points and their number. In the absence of a bound state, the dark lines can be used to suppress emission at a certain frequency in the spectrum. In the presence of a bound state, the total intensity of the emission spectrum can be significantly suppressed. The present results offer the possibility of control over the spontaneous emission with the dark lines due to the destructive interference in giant atoms. Published by the American Physical Society 2024
We study the emission spectrum of two distant qubits strongly coupled to a waveguide by using the numerical and analytical approaches, which are beyond the Markovian approximation and the rotating-wave approximation. The numerical approach combines the Dirac-Frenkel time-dependent variational principle with the multiple Davydov D1{D}_{1}D1​ ansatz. A transformed rotating-wave approximation (TRWA) treatment and a standard perturbation (SP) are used to analytically calculate the emission spectrum. It is found that the variational approach and the TRWA treatment yield accurate emission spectra of the two distant qubits in certain strong-coupling regimes while the SP breaks down. The emission spectrum is found to be asymmetric irrespective of the two-qubit distance and exhibits a single peak, double peaks, and multiple peaks depending on the two-qubit distance as well as the initial states. In sharp contrast with the single-qubit case, the excited-state populations of the two qubits can ultraslowly decay due to the subradiance even in the presence of a strong qubit-waveguide coupling, which in turn yields an ultranarrow emission line. Our results provide insights into the emission spectral features of the two distant qubits in the strong light-matter coupling regime.
We employ the Dirac-Frenkel variational principle and the multiple Davydov ansatz to study time-dependent fluorescence spectra of a driven qubit in the weak to strong qubit-reservoir coupling regimes, where both the Rabi frequency and the spontaneous decay rate are comparable to the transition frequency of the qubit. Our method agrees well with the time-local master-equation approach in the weak coupling regime, and offers a flexible way to compute the spectra from the bosonic dynamics instead of two-time correlation functions. While the perturbative master equation breaks down in the strong coupling regime, our method actually becomes more accurate due to the use of bosonic coherent states under certain conditions. We show that the counter-rotating coupling between the qubit and the reservoir has considerable contributions to the photon number dynamics and the spectra under strong driving conditions even when the coupling is moderately weak. The time-dependent spectra are found to be generally asymmetric, a feature that is derived from photon number dynamics. In addition, it is shown that the spectral profiles can be dramatically different from the Mollow triplet due to strong dissipation and/or multiphoton processes associated with the strong driving. Our formalism provides a unique perspective to interpret time-dependent spectra.
In this paper we investigate a coupled system of an initially excited two-level atom coupled to a monomode cavity,and compute spontaneous emission spectrum and mean population density emitted by the atom and the cavity using the quantum theory that accounts for theoretical derviation and numerical calculation.The spectra emitted separately by the atom and the cavity in of strong coupling region are dramatically different from those in weak coupling region at resonance.The cavity spectrum line splitting in the strong coupling region,however,a hole exists in the atomic spectrum in the weak coupling region.We study systematically the emission spectra when the atom and the cavity are detuned,and the results show that if the cavity linewidth is much smaller than the atomic linewidth(good cavity regime),photons are emitted at the cavity frequency even if the atom and the cavity are strongly detuned,and provide theoretic foundation for the apparently puzzling feature observed in the recent experiment.In this paper we computate the atomic and the cavity mean population densities each as a function of time and their relation to the luminous intensity, and offer a new insight into civity induced transparency effect.
The modification of the spontaneous emission spectrum has been studied in this paper in a four-level doubly driven N-type atomic system. In the presence of two coherent fields, emphasis has been given to studying the spectral distribution of spontaneous emission in the relaxation process of the initially prepared excited level. The phenomenon of quantum interference dynamically induced in the system by these fields can significantly change the spontaneous emission spectrum. We have shown the emergence of a two-peak spectrum where two widely separated symmetric peaks are associated with a sharp dark line at their mid-position. At different dynamic conditions, we have also shown that two symmetric peaks may appear in the spectrum with an extended dark zone between them. Depending on the values of the Rabi frequencies and the detunings of the external fields, one can achieve a large enhancement of very narrow spectral components within the spontaneous emission line shape under different conditions. The phenomenon of suppression of spectral line and the selective cancellation of spontaneous emission have also been discussed. The results shown in various cases are analysed by considering all possible dressed states corresponding to the bare state model. The influence of collision-induced effects on the spontaneous emission spectrum is investigated as a conditional case.
We study the influence of quantum interference on the spontaneous emission from an excited two-level atom when either the atomic upper or lower level is coupled by a coherent field to a third, usually higher-lying, state. In the case of the upper level coupling, destructive quantum interference between two competing decay amplitudes produces a dark line in the emission spectrum, a phenomenon that should not be confused with the well known population trapping, and a narrowing of one of the two side lobes that make up the spectral profile. Quantum interference is absent, instead, in the case of the lower level coupling, and the spectrum modified by the external driving field is just the incoherent superposition of two Lorentzian lines. We suggest a physical interpretation of these results. In addition, we compare the analytic predictions of the simplest nontrivial versions of these models with more realistic but nonanalytic descriptions and show, numerically, that the interference effects persist in the upper level case even when additional complications are taken into account.