Physical Review Letters

Observation of Quantum Beats in Photon Echoes and Optical Nutation

R. L. Shoemaker, Frederic A. Hopf

Published Dec 23, 1974• 53 citations

Abstract

We extend the technique of quantum-beat spectroscopy to the infrared region by utilizing the strong, directional absorption and emission which occurs in photon echoes and optical nutation. Using a vibrational transition of N${\mathrm{H}}_{2}$D, we have made the first observations of infrared quantum beats in these phenomena. The hyperfine splitting which produces the quantum beats has not been observed in Lamb-dip spectroscopy but is clearly resolved in these time domain studies.

DOI: 10.1103/physrevlett.33.1527

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Physical Review Letters

Observation of Quantum Beats in Photon Echoes and Optical Nutation

R. L. Shoemaker, Frederic A. Hopf

Published Dec 23, 1974• 53 citations

Publisher

Abstract

{\mathrm{H}}_{2}

D, we have made the first observations of infrared quantum beats in these phenomena. The hyperfine splitting which produces the quantum beats has not been observed in Lamb-dip spectroscopy but is clearly resolved in these time domain studies.

DOI: 10.1103/physrevlett.33.1527

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Physical Review AJun 1, 19767 citations

Photon-echo quantum beats on the 7P32−6S12 transition in cesium

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Physical Review AOct 1, 19798 citations

Quantum beats induced by spectral diffusion between independent two-level systems

Claudine Crépin

We analyze theoretically the time-resolved signal detected in three-pulse, photon echo experiments where several independent two-level systems are involved, in a case when the time delay T between the two last pulses is much longer than delay $\ensuremath{\tau}$ between the two first pulses. A spectral diffusion process on a long time scale is included in the calculation of the $\ensuremath{\tau}$-dependent response signal. If spectral diffusion occurs between the different systems, the signal exhibits quantum beats instead of the polarization interferences observed without spectral diffusion. This analysis provides different insights on dynamical processes and spectroscopy, as demonstrated in examples of experimental results obtained on vibrational dynamics of molecules embedded in matrices.We analyze theoretically the time-resolved signal detected in three-pulse, photon echo experiments where several independent two-level systems are involved, in a case when the time delay T between the two last pulses is much longer than delay $\ensuremath{\tau}$ between the two first pulses. A spectral diffusion process on a long time scale is included in the calculation of the $\ensuremath{\tau}$-dependent response signal. If spectral diffusion occurs between the different systems, the signal exhibits quantum beats instead of the polarization interferences observed without spectral diffusion. This analysis provides different insights on dynamical processes and spectroscopy, as demonstrated in examples of experimental results obtained on vibrational dynamics of molecules embedded in matrices.

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Quantum beats in the dressed state nutation

Xiaomin Feng, Lianshui Zhang, Jian Wang +2 more

In a V-shaped three-level double-resonance configuration, there is strong quantum beats superimposed in a nutation signal in the probe laser response. In this paper, the beats in the dressed state nutation is studied theoretically within dressed state picture and the result is presented. An important conclusion is that the strong quantum beats in such a configuration occurred mainly as a result of the intrinsic coherence of the dressed states. Our result extends the coherent transient study in bared atomic transition to dressed state transitions.In a V-shaped three-level double-resonance configuration, there is strong quantum beats superimposed in a nutation signal in the probe laser response. In this paper, the beats in the dressed state nutation is studied theoretically within dressed state picture and the result is presented. An important conclusion is that the strong quantum beats in such a configuration occurred mainly as a result of the intrinsic coherence of the dressed states. Our result extends the coherent transient study in bared atomic transition to dressed state transitions.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIENov 29, 20070 citations

{\mathrm{H}}_{2}

7{P}_{\frac{3}{2}}

level as well as those due to the Zeeman splitting of both ground and excited levels. Experimental data for both

F=3

and

F=4

hyperfine components of the

6{S}_{\frac{1}{2}}

ground state and for several echo delay times were fitted to calculated spectra, including corrections arising from Faraday rotation of the echo pulses.

Photon echo and optical nutation have been easily observed in

{\mathrm{C}}^{13}

{\mathrm{H}}_{3}

F and N

{\mathrm{H}}_{2}

D by applying Stark pulses which shift the molecular levels into resonance with cw laser radiation. Numerical computations of the nutation effect agree with observation, and echo characteristics closely follow predictions of existing theories. The $T_{2}^{}{}_{}{}^{\ensuremath{'}}$ pressure dependence, from infrared-echo measurements, indicates that

{\mathrm{C}}^{13}

{\mathrm{H}}_{3}

F relaxes primarily by rotational energy transfer.

The authors study the phenomenon of coherent Raman beats in

^{15}\mathrm{N}

{\mathrm{H}}_{3}

using a C

{\mathrm{O}}_{2}

laser and Stark switching. In particular, a three-level system in which the two upper levels always remain split by a few MHz is prepared by switching the transitions into resonance with a short Stark pulse whose bandwidth is large enough to coherently excite both transitions. When one of the coherently excited levels remains in resonance with the laser after the Stark pulse, this system exhibits a qualitatively new effect which has not been seen heretofore. For Stark shifts on the order of the upper-state splitting or smaller, the Raman beat is amplitude modulated at a frequency related to the optical nutation frequency. This is interpreted as being due to an interaction between the two-photon coherent Raman beat process and a single-photon optical nutation process which occurs simultaneously. Numerical calculations as well as a simple analytic model are presented to support this interpretation. By reducing the laser power, one can make the modulation of the Raman beat disappear. From the Raman signal in this regime the permanent electric dipole moment of

^{15}\mathrm{N}

{\mathrm{H}}_{3}

in an excited vibrational state is determined and the Raman beat decay rate measured. By comparing the latter result with a delayed optical nutation measurement we show that phase-changing collisions are negligible for the transition studied.