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Laurent Hilico - One of the best experts on this subject based on the ideXlab platform.
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hydrogen molecular ions for improved determination of fundamental constants
Physical Review A, 2016Co-Authors: Ph J Karr, Laurent Hilico, J C J Koelemeij, V I KorobovAbstract:An experimental scheme is proposed to help resolve the proton- (deuteron-) radius puzzle with rovibrational Two-Photon Spectroscopy of hydrogen molecular ions measured at high precision. The technique is also expected to measure other fundamental constants, such as the Rydberg constant and the electron-proton mass ratio, at a competitive level of precision compared to the existing schemes.
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Two Photon Spectroscopy of trapped hd ions in the lamb dicke regime
Physical Review A, 2013Co-Authors: Vu Quang Tran, Laurent Hilico, Jeanphilippe Karr, A Douillet, J C J KoelemeijAbstract:We study the feasibility of nearly-degenerate Two-Photon rovibrational Spectroscopy in ensembles of trapped, sympathetically cooled hydrogen molecular ions using a resonance-enhanced multiPhoton dissociation (REMPD) scheme. Taking advantage of quasi-coincidences in the rovibrational spectrum, the excitation lasers are tuned close to an intermediate level to resonantly enhance Two-Photon absorption. Realistic simulations of the REMPD signal are obtained using a four-level model that takes into account saturation effects, ion trajectories, laser frequency noise and redistribution of population by blackbody radiation. We show that the use of counterpropagating laser beams enables optical excitation in an effective Lamb-Dicke regime. Sub-Doppler lines having widths in the 100 Hz range can be observed with good signal-to-noise ratio for an optimal choice of laser detunings. Our results indicate the feasibility of molecular Spectroscopy at the $10^{-14}$ accuracy level for improved tests of molecular QED, a new determination of the proton-to-electron mass ratio, and studies of the time (in)dependence of the latter.
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polarizabilities light shifts and Two Photon transition probabilities between j 0 states of the h2 and d2 molecular ions
Journal of Physics B, 2001Co-Authors: Laurent Hilico, N Billy, Benoit Gremaud, Dominique DelandeAbstract:We present the computation of the Two-Photon transition matrix element between vibrational states of H2+ or D2+ of 1Se symmetry (i.e. Two J = 0 vibrational levels of the 1sσg electronic ground state). The method uses very accurate fully non-adiabatic wavefunctions of the non-relativistic problem. It is first applied to the calculation of the static polarizabilities; our results for the ground state are in excellent agreement with the literature, with an improved accuracy. The method is applied to the evaluation of the Two-Photon transition probabilities and light shifts. We also discuss the feasibility of a Two-Photon Spectroscopy experiment in H2+.
Patrick D Persaud - One of the best experts on this subject based on the ideXlab platform.
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dipole dipole interaction in Two Photon Spectroscopy of metallic nanohybrids
Journal of Physical Chemistry C, 2020Co-Authors: Mahi R Singh, Patrick D PersaudAbstract:We have developed a theory for the Two-Photon fluorescence in nanohybrids made of an ensemble of metallic nanorod shells and an ensemble of quantum emitters. A metallic nanorod shell is made of a m...
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dipole dipole interaction in Two Photon Spectroscopy of metallic nanohybrids
The Journal of Physical Chemistry, 2020Co-Authors: Mahi R Singh, Patrick D PersaudAbstract:We have developed a theory for the Two-Photon fluorescence in nanohybrids made of an ensemble of metallic nanorod shells and an ensemble of quantum emitters. A metallic nanorod shell is made of a metallic rod and dielectric shell. We consider that the quantum emitters are four-level quantum systems. When a probe laser light falls on the metallic nanorod shells, the surface plasmon polariton electric field is produced at the interface between the metallic nanorod and dielectric shell. This electric field, along with the probe field, induces dipoles in the quantum emitters and nanorod shells. These dipoles interact with each other via the dipole–dipole interaction. The Two-Photon fluorescence has been calculated by using the quantum density matrix method in the presence of the dipole–dipole interaction (coupling). Analytical expressions of the Two-Photon fluorescence have been derived in the presence of the dipole–dipole interaction. We showed that that the Two-Photon process is made of Two terms. The first term is the Two-Photon process due to the Two probe field Photons. On other the hand, the second term is made of one DDI field Photon and one probe field Photon. It is found that the surface plasmon polariton resonance energy is not resonant with the exciton energy, the Two-Photon fluorescence spectrum splits from one peak to three peaks. The splitting in the spectrum is due to the presence of the dressed states created in the system due to the strong dipole–dipole interaction. We also compared our theory with the experimental data of the metallic nanohybrid system made of metallic nanorod shells and quantum emitters (T790 molecules) and found a good agreement between the theory and the experiments.
W Ubachs - One of the best experts on this subject based on the ideXlab platform.
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dissociation energy of the hydrogen molecule at 10 9 accuracy
Physical Review Letters, 2018Co-Authors: Cunfeng Cheng, J Hussels, M L Niu, Hendrick L Bethlem, K S E Eikema, E J Salumbides, W Ubachs, Maximilian Beyer, Nicolas Holsch, Josef A AgnerAbstract:The ionization energy of ortho-H_{2} has been determined to be E_{I}^{o}(H_{2})/(hc)=124 357.238 062(25) cm^{-1} from measurements of the GK(1,1)-X(0,1) interval by Doppler-free, Two-Photon Spectroscopy using a narrow band 179-nm laser source and the ionization energy of the GK(1,1) state by continuous-wave, near-infrared laser Spectroscopy. E_{I}^{o}(H_{2}) was used to derive the dissociation energy of H_{2}, D_{0}^{N=1}(H_{2}), at 35 999.582 894(25) cm^{-1} with a precision that is more than one order of magnitude better than all previous results. The new result challenges calculations of this quantity and represents a benchmark value for future relativistic and QED calculations of molecular energies.
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precision Spectroscopy of high rotational states in h 2 investigated by doppler free Two Photon laser Spectroscopy in the ef 1 sigma g x 1 sigma g system
Physical Review A, 2012Co-Authors: G D Dickenson, E J Salumbides, M Niu, Christian Jungen, S C Ross, W UbachsAbstract:Recently a high precision spectroscopic investigation of the EF1 Sigma(+)(g)-X-1 Sigma(+)(g) system of molecular hydrogen was reported yielding information on QED and relativistic effects in a sequence of rotational quantum states in the X-1 Sigma(+)(g) ground state of the H-2 molecule [Salumbides et al., Phys. Rev. Lett. 107, 043005 (2011)]. The present paper presents a more detailed description of the methods and results. Furthermore, the paper serves as a stepping stone towards a continuation of the previous study by extending the known level structure of the EF1 Sigma(+)(g) state to highly excited rovibrational levels through Doppler-free Two-Photon Spectroscopy. Based on combination differences between vibrational levels in the ground state, and between three rotational branches (O, Q, and S branches) assignments of excited EF1 Sigma(+)(g) levels, involving high vibrational and rotational quantum numbers, can be unambiguously made. For the higher EF1 Sigma(+)(g) levels, where no combination differences are available, calculations were performed using the multichannel quantum defect method, for a broad class of vibrational and rotational levels up to J = 19. These predictions were used for assigning high-J EF levels and are found to be accurate within 5 cm(-1).
Thomas Udem - One of the best experts on this subject based on the ideXlab platform.
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Two Photon frequency comb Spectroscopy of atomic hydrogen with chirped laser pulses
Frontiers in Optics, 2015Co-Authors: Arthur Matveev, T W Hansch, Dylan C Yost, Alexey Grinin, Thomas UdemAbstract:We report on the results of Two-Photon Spectroscopy of 1S-3S transition in atomic hydrogen using picosecond mode-locked laser. The chirp of the laser pulses leads to frequency shift proportional to the velocity of the atoms.
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quantum interference in Two Photon frequency comb Spectroscopy
Physical Review A, 2014Co-Authors: Dylan C Yost, T W Hansch, Arthur Matveev, Axel Beyer, Elisabeth Peters, Thomas UdemAbstract:Quantum interference arising from spontaneous emission, or cross-damping, is an important yet frequently overlooked systematic in precision Spectroscopy experiments which aim to determine a transition frequency with an uncertainty smaller than the natural linewidth. Here, we calculate the effects of such interference in Two-Photon frequency-comb Spectroscopy using a perturbative approach and by integration of the density matrix equations. We then apply these techniques to the Two-Photon Spectroscopy of the hydrogen $1S\ensuremath{-}3S$ transition currently being performed in our group. Depending on the detection geometry, we find distortions of the line shapes which can lead to systematic errors of $\ensuremath{\sim}$1 kHz if such interference effects are ignored in the data analysis. This result is independent of whether a cw laser or frequency comb is used for the excitation. Finally, we propose a time-dependent detection scheme which, when used in conjunction with frequency-comb excitation, can mitigate the line distortions arising from such interference.
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improved measurement of the hydrogen 1s 2s transition frequency
Physical Review Letters, 2011Co-Authors: Christian G Parthey, Arthur Matveev, Janis Alnis, Randolf Pohl, Birgitta Bernhardt, Axel Beyer, Ronald Holzwarth, Aliaksei Maistrou, Katharina Predehl, Thomas UdemAbstract:We have measured the $1S\char21{}2S$ transition frequency in atomic hydrogen via Two-Photon Spectroscopy on a 5.8 K atomic beam. We obtain ${f}_{1S\char21{}2S}=2\text{ }466\text{ }061\text{ }413\text{ }187\text{ }035\text{ }(10)\text{ }\mathrm{Hz}$ for the hyperfine centroid, in agreement with, but 3.3 times better than the previous result [M. Fischer et al., Phys. Rev. Lett. 92, 230802 (2004)]. The improvement to a fractional frequency uncertainty of $4.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}15}$ arises mainly from an improved stability of the Spectroscopy laser, and a better determination of the main systematic uncertainties, namely, the second order Doppler and ac and dc Stark shifts. The probe laser frequency was phase coherently linked to the mobile cesium fountain clock FOM via a frequency comb.
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precision measurement of the hydrogen deuterium 1s 2s isotope shift
Physical Review Letters, 2010Co-Authors: Christian G Parthey, Arthur Matveev, Thomas Udem, Janis Alnis, Randolf Pohl, Ulrich D Jentschura, Nikolai N Kolachevsky, T W HanschAbstract:Measuring the hydrogen-deuterium isotope shift via Two-Photon Spectroscopy of the $1S\ensuremath{-}2S$ transition, we obtain 670 994 334 606(15) Hz. This is a 10-times improvement over the previous best measurement [A. Huber et al., Phys. Rev. Lett. 80, 468 (1998)] confirming its frequency value. A calculation of the difference of the mean square charge radii of deuterium and hydrogen results in $⟨{r}^{2}{⟩}_{d}\ensuremath{-}⟨{r}^{2}{⟩}_{p}=3.820\text{ }07(65)\text{ }\text{ }{\mathrm{fm}}^{2}$, a more than Twofold improvement compared to the former value.
Dezső Horvath - One of the best experts on this subject based on the ideXlab platform.
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Two Photon laser Spectroscopy of antiprotonic helium and the antiproton to electron mass ratio
Nature, 2011Co-Authors: Masaki Hori, Anna Sótér, R S Hayano, E Widmann, D Barna, A Dax, S Friedreich, B Juhasz, T Pask, Dezső HorvathAbstract:The principle of CPT (charge, parity, time) symmetry implies that antimatter particles have exactly the same mass and absolute value of charge as their particle counterparts. Hori et al. test this principle by performing high-precision, Two-Photon Spectroscopy of antiprotonic helium. By comparing the results with calculations, they derive a value for the antiproton-to-electron mass ratio, the first time this quantity has been determined. The result agrees with the proton-to-electron value known to a similar precision. Moreover, the work improves the accuracy with which the charge-to-mass ratio of the antiproton can be compared to that of the proton by four orders of magnitude. Physical laws are believed to be invariant under the combined transformations of charge, parity and time reversal (CPT symmetry1). This implies that an antimatter particle has exactly the same mass and absolute value of charge as its particle counterpart. Metastable antiprotonic helium ( He+) is a three-body atom2 consisting of a normal helium nucleus, an electron in its ground state and an antiproton ( ) occupying a Rydberg state with high principal and angular momentum quantum numbers, respectively n and l, such that n ≈ l + 1 ≈ 38. These atoms are amenable to precision laser Spectroscopy, the results of which can in principle be used to determine the antiproton-to-electron mass ratio and to constrain the equality between the antiproton and proton charges and masses. Here we report Two-Photon Spectroscopy of antiprotonic helium, in which 3He+ and 4He+ isotopes are irradiated by Two counter-propagating laser beams. This excites nonlinear, Two-Photon transitions of the antiproton of the type (n, l) → (n − 2, l − 2) at deep-ultraviolet wavelengths (λ = 139.8, 193.0 and 197.0 nm), which partly cancel the Doppler broadening of the laser resonance caused by the thermal motion of the atoms. The resulting narrow spectral lines allowed us to measure three transition frequencies with fractional precisions of 2.3–5 parts in 109. By comparing the results with three-body quantum electrodynamics calculations, we derived an antiproton-to-electron mass ratio of 1,836.1526736(23), where the parenthetical error represents one standard deviation. This agrees with the proton-to-electron value known to a similar precision.
