Quantum coherence of collective states plays a pivotal role in understanding many-body cooperative behaviors. Collective coherences between the ground state and excited states in potassium atoms were previously revealed; however, the coherence between collectively excited states has hitherto been overlooked, and its observation has remained challenging. Here we present a joint experimental and theoretical investigation of coherence effects in K atomic vapor using two-dimensional coherent spectroscopy. By collecting zero-quantum, double-quantum, and double-quantum--zero-quantum two-dimensional spectra, distinct coherence signatures are spectroscopically accessible. The experimental spectra are well reproduced by numerically solving the time dependence of the Lindblad equation, and further analyses unveil nonradiative coherence as the origin of the observations. Our work provides comprehensive insight into the collective coherence effect in multiatom systems.Quantum coherence of collective states plays a pivotal role in understanding many-body cooperative behaviors. Collective coherences between the ground state and excited states in potassium atoms were previously revealed; however, the coherence between collectively excited states has hitherto been overlooked, and its observation has remained challenging. Here we present a joint experimental and theoretical investigation of coherence effects in K atomic vapor using two-dimensional coherent spectroscopy. By collecting zero-quantum, double-quantum, and double-quantum--zero-quantum two-dimensional spectra, distinct coherence signatures are spectroscopically accessible. The experimental spectra are well reproduced by numerically solving the time dependence of the Lindblad equation, and further analyses unveil nonradiative coherence as the origin of the observations. Our work provides comprehensive insight into the collective coherence effect in multiatom systems.

Physical Review AJan 3, 20252 citations

COLLECTIVE EFFECTS IN ATOMS.

Bernard Roulet, Ph. Nozières

Jan 1, 19680 citations

Collective excitations in atoms

F. J. Kok

Jan 1, 19720 citations

Absorption spectra of a system of atoms under cooperative conditions

Akundi Suguna, G. S. Agarwal

The problem of the energy absorption from a weak probe field by a system of atoms driven by a coherent laser field is considered with special reference to the collective behavior of the atomic system. The changes in the nature of the absorption spectra as the intensity of the coherent laser field is changed are examined explicitly for a system of two atoms. Cooperative effects are shown to be important for weak laser fields. For strong fields, it is shown that the absorption spectra under cooperative conditions differ from those without cooperative conditions only by a scale factor.The problem of the energy absorption from a weak probe field by a system of atoms driven by a coherent laser field is considered with special reference to the collective behavior of the atomic system. The changes in the nature of the absorption spectra as the intensity of the coherent laser field is changed are examined explicitly for a system of two atoms. Cooperative effects are shown to be important for weak laser fields. For strong fields, it is shown that the absorption spectra under cooperative conditions differ from those without cooperative conditions only by a scale factor.

Physical Review ANov 1, 197910 citations

Collective atomic effects in resonance fluorescence: Dipole-dipole interaction

Helen S. Freedhoff

The resonance fluorescence of a two-atom system interacting collectively with an intense driving field is studied. The first-order dispersion forces, or dipole-dipole interaction, between the atoms is included as well. The scattered-light spectrum is found to differ considerably from the single-atom spectrum even for very intense driving fields, in direct contrast with the results obtained by Agarwal et al., who studied the two-atom system but neglected the dipole-dipole interaction. The effects of collective scattering are calculated on the fluorescence spectra of idealized beams of atoms moving with uniform velocity, for a number of different number densities $〈N〉$ .The resonance fluorescence of a two-atom system interacting collectively with an intense driving field is studied. The first-order dispersion forces, or dipole-dipole interaction, between the atoms is included as well. The scattered-light spectrum is found to differ considerably from the single-atom spectrum even for very intense driving fields, in direct contrast with the results obtained by Agarwal et al., who studied the two-atom system but neglected the dipole-dipole interaction. The effects of collective scattering are calculated on the fluorescence spectra of idealized beams of atoms moving with uniform velocity, for a number of different number densities $〈N〉$.

Physical Review AMar 1, 197958 citations

〈N〉