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David Sarkisyan

Bio: David Sarkisyan is an academic researcher from Armenian National Academy of Sciences. The author has contributed to research in topics: Magnetic field & Hyperfine structure. The author has an hindex of 30, co-authored 148 publications receiving 2750 citations.


Papers
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Journal ArticleDOI
TL;DR: The demonstration of cooperative interactions in an easily scalable system opens the door to a new domain for nonlinear optics.
Abstract: We present an experimental measurement of the cooperative Lamb shift and the Lorentz shift using a nanothickness atomic vapor layer with tunable thickness and atomic density. The cooperative Lamb shift arises due to the exchange of virtual photons between identical atoms. The interference between the forward and backward propagating virtual fields is confirmed by the thickness dependence of the shift, which has a spatial frequency equal to twice that of the optical field. The demonstration of cooperative interactions in an easily scalable system opens the door to a new domain for nonlinear optics.

242 citations

Journal ArticleDOI
TL;DR: In this article, an extremely thin cell (ETC) with the thickness of Cs atomic vapour layer in the range of 150-300 nm has been developed for the first time, which can completely resolve each particular hyperfine transition of both 85 Rb and 87 Rb isotopes in D 2 line fluorescence spectrum.

144 citations

Journal ArticleDOI
01 Jul 2003-EPL
TL;DR: In this article, it was shown that the dipole response in a thin cell of dilute vapour exhibits sub-Doppler features due to the relative enhancement of the slow atom contribution, with respect to the transient nature of the interaction with moving atoms.
Abstract: In a thin cell of dilute vapour, the absorption spectrum exhibits sub-Doppler features due to the relative enhancement of the slow atom contribution, with respect to the transient nature of the interaction with moving atoms. For a two-level system in the linear regime, the narrowest response is predicted to be found for a λ/2 thickness, as an effect of the coherent character of the dipole response as early described by Romer and Dicke (Phys. Rev., 99 (1955) 532) in the microwave regime. We report here on the direct observation of this effect in the optical regime in an ultra-thin vapour cell. This effect is shown to vanish for a thickness equal to λ, and a revival is observed at 3λ/2, as expected from the predicted λ-periodicity. The experiment is performed on the D1 resonance line of Cs vapour (λ = 894 nm), in a specially designed cell, whose thickness varies locally.

112 citations

Journal ArticleDOI
TL;DR: In this article, the authors compare the behavior of absorption and of resonance fluorescence spectra in an extremely thin Rb vapor cell as a function of the ratio of $L∕\ensuremath{\lambda}$, with $L$ the cell thickness, and show that the Dicke-type coherent narrowing is observed only in transmission measurements, in the linear regime, with its typical collapse and revival.
Abstract: We compare the behavior of absorption and of resonance fluorescence spectra in an extremely thin Rb vapor cell as a function of the ratio of $L∕\ensuremath{\lambda}$, with $L$ the cell thickness $(L\ensuremath{\sim}150--1800\phantom{\rule{0.3em}{0ex}}\mathrm{nm})$ and $\ensuremath{\lambda}$ the wavelength of the Rb ${D}_{2}$ line $(\ensuremath{\lambda}=780\phantom{\rule{0.3em}{0ex}}\mathrm{mn})$. The Dicke-type coherent narrowing [G. Dutier et al., Europhys. Lett. 63, 35 (2003)] is observed only in transmission measurements, in the linear regime, with its typical collapse and revival, which reaches a maximum for $L=(2n+1)\ensuremath{\lambda}∕2$ ($n$ integer). It is shown not to appear in fluorescence, whose behavior-amplitude, and spectral width, is more monotonic with $L$. Conversely, at high-intensity, the sub-Doppler saturation effects are shown to be the most visible in transmission around $L=n\ensuremath{\lambda}$.

107 citations

Journal ArticleDOI
01 Mar 2007-EPL
TL;DR: In this paper, the van der Waals atom-surface attraction, scaling as C3z?3 for z the atom surface distance, is expected to be valid in the distance range 1?1000?nm, covering 8?10 orders of magnitudes in the interaction energy.
Abstract: The van der Waals atom-surface attraction, scaling as C3z?3 for z the atom-surface distance, is expected to be valid in the distance range 1?1000?nm, covering 8?10 orders of magnitudes in the interaction energy. A Cs vapour nanocell allows us to analyze the spectroscopic modifications induced by the atom-surface attraction on the 6P3/2 ? 6D5/2 transition. The measured C3 value is found to be independent of the thickness in the explored range 40?130?nm, and is in agreement with an elementary theoretical prediction. We also discuss the specific interest of exploring short distances and large interaction energy.

89 citations


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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: In this article, the time dependence of ρ11, ρ22 and ρ12 under steady-state conditions was analyzed under a light field interaction V = -μ12Ee iωt + c.c.
Abstract: (b) Write out the equations for the time dependence of ρ11, ρ22, ρ12 and ρ21 assuming that a light field interaction V = -μ12Ee iωt + c.c. couples only levels |1> and |2>, and that the excited levels exhibit spontaneous decay. (8 marks) (c) Under steady-state conditions, find the ratio of populations in states |2> and |3>. (3 marks) (d) Find the slowly varying amplitude ̃ ρ 12 of the polarization ρ12 = ̃ ρ 12e iωt . (6 marks) (e) In the limiting case that no decay is possible from intermediate level |3>, what is the ground state population ρ11(∞)? (2 marks) 2. (15 marks total) In a 2-level atom system subjected to a strong field, dressed states are created in the form |D1(n)> = sin θ |1,n> + cos θ |2,n-1> |D2(n)> = cos θ |1,n> sin θ |2,n-1>

1,872 citations

Journal ArticleDOI
TL;DR: The last volume of the Progress in Optics series as discussed by the authors contains seven chapters on widely diverging topics, written by well-known authorities in their fields, including laser selective photophysics and photochemistry, laser phase profile generation, laser beamforming, and laser laser light emission from high-current surface spark discharges.
Abstract: Have you ever felt that the very title, Progress in Optics, conjured an image in your mind? Don’t you see a row of handsomely printed books, bearing the editorial stamp of one of the most brilliant members of the optics community, and chronicling the field of optics since the invention of the laser? If so, you are certain to move the bookend to make room for Volume 16, the latest of this series. It contains seven chapters on widely diverging topics, written by well-known authorities in their fields. These are: 1) Laser Selective Photophysics and Photochemistry by V. S. Letokhov, 2) Recent Advances in Phase Profiles (sic) Generation by J. J. Clair and C. I. Abitbol, 3 ) Computer-Generated Holograms: Techniques and Applications by W.-H. Lee, 4) Speckle Interferometry by A. E. Ennos, 5 ) Deformation Invariant, Space-Variant Optical Pattern Recognition by D. Casasent and D. Psaltis, 6) Light Emission from High-Current Surface-Spark Discharges by R. E. Beverly, and 7) Semiclassical Radiation Theory within a QuantumMechanical Framework by I. R. Senitzkt. The breadth of topic matter spanned by these chapters makes it impossible, for this reviewer at least, to pass judgement on the comprehensiveness, relevance, and completeness of every chapter. With an editorial board as prominent as that of Progress in Optics, however, it seems hardly likely that such comments should be necessary. It should certainly be possible to take the authority of each author as credible. The only remaining judgment to be made on these chapters is their readability. In short, what are they like to read? The first sentence of the first chapter greets the eye with an obvious typographical error: “The creation of coherent laser light source, that have tunable radiation, opened the . . . .” Two pages later we find: “When two types of atoms or molecules of different isotopic composition ( A and B ) have even one spectral line that does not overlap with others, it is pos-

1,071 citations

Journal ArticleDOI
TL;DR: In this article, the effects of electric fields on the optical transitions of excited Rydberg states are exploited to probe very weak microwave electric fields with atoms, which can be used as highly sensitive magnetic-field sensors.
Abstract: Atoms can be used as highly sensitive magnetic-field sensors. By exploiting the effects of electric fields on the optical transitions of excited Rydberg states, it is now demonstrated that it is also possible to probe very weak microwave electric fields with atoms.

488 citations