Sideband Spectroscopy Research Articles

Photo and X˗ray induced luminescences of Eu3+˗doped sodium alumino boro˗tellurite oxyfluoride scintillating glass for X˗ray detecting material

The spectroscopy features of sodium alumino boro˗tellurite oxyfluoride glasses doped with various molar fractions of Eu2O3 ions (TBANEu) are studied through absorbance, excitation, emission, and decay curves. The excitation data are used following phonon side band spectroscopy to evaluate the phonon energy (1326 cm-1) of the glass host. The densities, molar volumes, and refractive indices, including the Ω2,4,6 parameters of fabricated glasses are studied. The magnitudes of laser properties like effective line widths, branching ratios, and emission cross˗sections obtained for the Eu3+:5D0→7F2 transition could be useful for reddish-orange lighting devices application. Additionally the quantum efficiency estimated from experimental and calculated lifetimes is about ˃ 70% for the 5D0 level luminescence of TBANEu glasses. Upon 395 nm radiation, the current glass system can exhibit color coordinates close to (0.647, 0.351) for reddish˗orange light as performed by the CIE1931 chromaticity diagram. The integral scintillation intensities of TBANEu glasses were determined using the X˗ray excitation and observed that the TBANEu20 glass showed a highest scintillation efficiency of 39%, resulting in scintillator and X˗ray sensing device applications.

Large Single-Phonon Optomechanical Coupling Between Quantum Dots and Tightly Confined Surface Acoustic Waves in the Quantum Regime

Surface acoustic waves (SAWs) coupled to quantum dots (QDs), trapped atoms and ions, and point defects have been proposed as quantum transduction platforms, yet the requisite coupling rates and cavity lifetimes have not been experimentally established. Although the interaction mechanism varies, small acoustic cavities with large zero-point motion are required for high efficiencies. We experimentally establish the feasibility of this platform through electro- and optomechanical characterization of tightly focusing, single-mode Gaussian SAW cavities at approximately 3.6 GHz on $\mathrm{Ga}\mathrm{As}$. We explore the performance limits of the platform by fabricating SAW cavities with mode volumes approaching $6{\ensuremath{\lambda}}^{3}$ and linewidths less than 1 MHz. Employing strain-coupled single $\mathrm{In}\mathrm{As}$ QDs as optomechanical intermediaries, we measure single-phonon optomechanical coupling rates ${g}_{0}\ensuremath{\approx}2\ensuremath{\pi}\ifmmode\times\else\texttimes\fi{}1.2$ MHz. Sideband scattering rates thus exceed intrinsic phonon loss, indicating the potential for quantum optical readout and transduction of cavity phonon states. To demonstrate the feasibility of this platform for low-noise ground-state quantum transduction, we develop a fiber-based confocal microscope in a dilution refrigerator and perform single-QD resonance fluorescence sideband spectroscopy at millikelvin temperatures. These measurements show conversion between microwave phonons and optical photons with sub-natural linewidths.

Characterizing particle-like charge-migration dynamics with high-order harmonic sideband spectroscopy

We introduce high-harmonic sideband spectroscopy (HHSS) and show that it can be a robust probe of attosecond charge migration (CM) in a halogenated carbon-chain molecule. We simulate both the CM and harmonic-generation (HHG) dynamics using ab initio time-dependent density-functional theory. We find that CM dynamics initiated along the molecular backbone induces sidebands in the HHG spectrum driven by a delayed laser pulse that is polarized perpendicular to the molecular axis. Monitoring the spectrum as either the HHG laser frequency or the relative delay is scanned allows for the extraction of detailed information about the time-domain characteristics of the CM process.

Spectroscopic investigation of the different complexation and extraction properties of diastereomeric diglycolamide ligands

Abstract (2R,2′S)-2,2′-oxybis-(N,N-didecylpropanamide) (cis-mTDDGA) and (2R,2′R)-2,2′-oxybis-(N,N-didecylpropanamide) (trans-mTDDGA) were studied using time-resolved laser fluorescence spectroscopy (TRLFS), vibronic side-band spectroscopy (VSBS) and density functional theory calculations (DFT) to find reasons for their different extraction properties. Stability constants of the respective Cm(III) and Eu(III) complexes show cis-mTDDGA to be the superior ligand which is in agreement with results from extraction experiments. cis-mTDDGA extracts Cm(III) and Eu(III) as 1:3 complexes. In case of trans-mTDDGA, 1:2 complexes of the form [M(trans-mTDDGA)2(η1-NO3)(H2O)2]2+ (M = Cm, Eu) are extracted additionally to the 1:3 complexes. VSBS and DFT confirm the presence of inner-sphere nitrate in the 1:2 complex.

Structural characterisation of hydrolysed Cm(III)-EDTA solution species under alkaline conditions: a TRLFS, vibronic side-band and quantum chemical study

We present a combined theoretical and experimental study of the Cm(III)-EDTA system in alkaline aqueous solutions. Time-resolved laser-fluorescence spectroscopy and vibronic side-band spectroscopy measurements are performed with , and . The evaluation of the TRLFS spectra and corresponding fluorescence lifetimes hints towards the predominance of Cm(EDTA) at pH = 7, with the subsequent formation of the hydrolysis species Cm(OH)(EDTA) with increasing pH. This speciation scheme is further supported by the excellent agreement obtained between experimental and calculated vibronic side bands. The relative stabilities of the complexes Cm(OH)(EDTA) with n = 0−2 and p = 1−2 are discussed on the basis of the equilibrium constants calculated from quantum chemical calculations.

AC-gate controlled transport sideband spectroscopy in GaAs quantum channels

A modeling investigation is conducted on the quantum transport in an n-type split-gate structure controlled by either an AC finger gate or an AC top gate. The quantum conductance is numerically computed for three different sideband approximations. The results show that various quasi-bound states (QBSs) are formed under the competing effects of photon emission and absorption at different sidebands. Additionally, it is shown that the structure of the QBSs depends on the relative proportion of an electron resonance transmission and an electron resonance reflectance induced by a sideband. Furthermore, the number of QBSs formed increases with the number of sidebands considered in the analysis.

Optical Superresolution Sensing of a Trapped Ion's Wave Packet Size.

We demonstrate superresolution optical sensing of the size of the wave packet of a single trapped ion. Our method extends the well-known ground state depletion (GSD) technique to the coherent regime. Here, we use a hollow beam to strongly saturate a coherently driven dipole-forbidden transition around a subdiffraction limited area at its center and observe state dependent fluorescence. By spatially scanning this laser beam over a single trapped ^{40}Ca^{+} ion, we are able to measure the wave packet sizes of cooled ions. Using a depletion beam waist of 4.2(1) μm we reach a spatial resolution which allows us to determine a wave packet size of 39(9)nm for a near ground state cooled ion. This value matches an independently deduced value of 32(2)nm, calculated from resolved sideband spectroscopy measurements. Finally, we discuss the ultimate resolution limits of our adapted GSD imaging technique in view of applications to direct quantum wave packet imaging.

Stabilizing a laser frequency by the Pound-Drever-Hall technique with an acousto-optic modulator.

We develop and demonstrate a method of optical phase modulation in the Pound-Drever-Hall (PDH) technique. The phase modulation in this paper is realized by an acousto-optic modulator (AOM) operating in the Bragg diffraction regime. In this process, a light beam separated from a laser (780 nm) is sent through the AOM twice and coupled to a high finesse Fabry-Perot cavity. Then, the light power coupling into the cavity is stabilized by modulating the optical amplitude with this AOM. The coupling light power is stabilized to a level of 10-3. In the meantime, the PDH error signal is obtained by modulating the optical phase with the same AOM. After the error signal is fed back to the laser current, the laser linewidth is suppressed to approximately 907.91 Hz. This method of phase modulation is simple and convenient, and we believe it can be widely used in modulation transfer spectroscopy and frequency-modulation sideband spectroscopy.

Trivalent Actinide Ions Showing Tenfold Coordination in Solution.

Trivalent actinides generally exhibit ninefold coordination in solution. 2,6-Bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine (nPr-BTP), a tridentate nitrogen donor ligand, is known to form ninefold coordinated 1:3 complexes, [An(nPr-BTP)3]3+ (An = U, Pu, Am, Cm) in solution. We report a Cm(III) complex with tenfold coordination in solution, [Cm(nPr-BTP)3(NO3)]2+. This species was identified using time-resolved laser fluorescence spectroscopy (TRLFS), vibronic side band spectroscopy (VSBS), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT). Adding nitrate to a solution of the [Cm(nPr-BTP)3]3+ complex in 2-propanol shifts the Cm(III) emission band from 613.1 to 617.3 nm. This bathochromic shift is due to a higher coordination number of the Cm(III) ion in solution, in agreement with the formation of the [Cm(nPr-BTP)3(NO3)]2+ complex. The formation of this complex exhibits slow kinetics in the range of 5 to 12 days, depending on the water content of the solvent. Formation of a complex [Cm(nPr-BTP)3(X)]2+ was not observed for anions other than nitrate (X- = NO2-, CN-, or OTf-). The formation of the [Cm(nPr-BTP)3(NO3)]2+ complex was studied as a function of NO3- and nPr-BTP concentrations, and slope analyses confirmed the addition of one nitrate anion to the [Cm(nPr-BTP)3]3+ complex. Experiments with varied nPr-BTP concentration show that [Cm(nPr-BTP)3(NO3)]2+ only forms at nPr-BTP concentrations below 10-4 mol/L whereas for concentrations greater than 10-4 mol/L the formation of the tenfold species is suppressed and [Cm(nPr-BTP)3]3+ is the only species present. The presence of the tenfold coordinated complex is supported by VSBS, XPS, and DFT calculations. The vibronic side band of the [Cm(nPr-BTP)3(NO3)]2+ complex exhibits a nitrate stretching mode not observed in the [Cm(nPr-BTP)3]3+ complex. Moreover, XPS on [M(nPr-BTP)3(NO3)](NO3)2 (M = Eu, Am) yields signals from both non-coordinated and coordinated nitrate. Finally, DFT calculations reveal that the energetically most favored structure is obtained if the nitrate is positioned on the C2 axis of the D3 symmetrical [Cm(nPr-BTP)3]3+ complex with a bond distance of 413 pm. Combining results from TRLFS, VSBS, XPS, and DFT provides sound evidence for a unique tenfold coordinated Cm(III) complex in solution-a novelty in An(III) solution chemistry.

Determination of quantum defect for the Rydberg P series of Ca II

We present an experimental investigation of the Rydberg 23P1/2 state of single, laser-cooled 40Ca+ ions in a radiofrequency ion trap. Using micromotion sideband spectroscopy on a narrow quadrupole transition, the oscillating electric field at the ion position was precisely characterised, and the modulation of the Rydberg transition due to this field was minimised. From a correlated fit to this P line and previously measured P and F level energies of Ca II, we have determined the ionization energy of 95 751.916(32) cm−1, in agreement with the accepted value, and the quantum defect for the nP1/2 states.

Spin and motion dynamics with zigzag ion crystals in transverse magnetic gradients

We investigate the dynamics of ion crystals in zigzag configuration in transverse magnetic field gradients. A surface-electrode Paul trap is employed to trap 40Ca+ ions and features submerged current wires to generate magnetic field gradients of up to 16.3(9) T m−1 at the ions position. With the gradient aligned in the direction perpendicular to the axis of weakest confinement, along which linear ion crystals are formed, we demonstrate magnetic field gradient induced coupling between the spin and ion motion. We perform sideband spectroscopy upon directly driving the spins with a radiofrequency field for crystals of three ions on their linear-to-zigzag structural transition. Furthermore, we observe the rich excitation spectrum of vibrational modes in a planar crystal comprised of four ions.

Development of Eu3+ doped bismuth germanate glasses for red laser applications

The intense red-emitting Eu3+ doped bismuth germanate glasses have been prepared by melt quenching technique with the chemical composition of (100-x)(0.2Bi2O3–0.8GeO2)-xEu2O3 (x = 0.5–2 mol%). Spectroscopic analysis have been performed through FTIR, absorption, luminescence and decay time measurements to enlighten the structural and optical properties of these systems. The bonding parameter (δ) and optical band gap (Eg) of prepared glasses have been calculated from the optical absorption spectra. Phonon side band spectroscopy was used to explore the phonon energy, electron-phonon coupling strength and multiphonon relaxation rate of Eu3+ doped bismuth germanate glasses. Under near UV excitation at 393 nm enhanced red emission is observed at 611 nm (5D0 → 7F2) with rising Eu3+ content. The radiative properties including transition probability (A), branching ratio (βR), stimulated emission cross-section (σe) and decay time (τR) for different excited states have been evaluated by using Judd-Ofelt parameters determined from the emission spectra. The calculated values of asymmetric ratio (R/O) and Ω2 suggest high asymmetric environment for Eu3+ ions and high covalency for EuO bond which are also confirmed by positive values of bonding parameter. The decay curves of 5D0 → 7F2 transition were well fitted to single exponential function for all the concentrations. The slight increase in decay times with rising Eu3+ ion content is due to the increase in the asymmetry of the local environment at the Eu3+ ion site. The CIE color coordinates (x,y) of the prepared glasses are within the range of 0.637–0.648 and 0.347–0.350 and are very close to the standard red color (0.67, 0.33) suggesting pure intense red emission is achieved. The results indicate that BGEx glasses are promising materials for red laser applications.

Investigations on the spectroscopic properties and local structure of Eu3+ ions in zinc telluro-fluoroborate glasses for red laser applications

The strong red emitting Eu3+ doped Zinc telluro-fluoroborate glasses with the chemical composition (30–x)B2O3+30TeO2+16ZnO+10ZnF2+7CaF2+7BaF2+xEu2O3 (where x = 0.1, 0.25, 0.5, 1.0, 2.0 and 3.0 in wt%) have been prepared following the melt-quenching technique and their structural, spectroscopic behavior were characterized. The local structure and vibronic spectral analysis were performed in order to correlate them with the local field environment of Eu3+ ions in the prepared Zinc telluro-fluoroborate glasses on the basis of FTIR, Raman, Phonon sideband spectroscopy. Fundamental stretching units of Te–O bond in TeO3/TeO4 units, stretching of B–O bond in BO3/BO4 units and bending vibrations of Te–O–Te/B–O–B bonds were identified through FTIR and Raman spectral analysis. The Nephelauxetic intensity ratios (β) and bonding parameter (δ) values obtained from the absorption bands reveals the covalent nature of the Eu–O bond in the prepared glasses. Phonon sidebands appear around 505, 732 and 999 cm−1 results from the combined bending vibrations of Zn−O−Te and Te−O−Te in borate network, combined stretching vibrations of TeO4 trigonal bipyramidal (tbp) units with the formation of vitreous B2O3 due to the bending vibration of B–O–B linkages, and B−O bond stretching in BO4 units, stretching modes of terminal oxygens (B–O−) belong to the BO2O metaborate triangles respectively. The JO intensity parameters (Ωλ) and the asymmetric intensity ratio (R) values calculated from the emission spectra have been used to explore the nature of the bonding and asymmetry around the Eu-ligand field environment. The increasing Ω2 intensity parameters and R values confirms the higher asymmetry around the Eu3+ ions and covalency of Eu–O. The JO intensity parameters were used to estimate the radiative properties such as transition probability (A), stimulated emission cross-section (σPE), branching ratio values (β) and radiative lifetimes (τR) for the observed emission transitions. The excited state lifetime for the 5D0 level of the Eu3+ ions exhibit single exponential behavior for all the titled glasses and found to increase with the increase in Eu3+ ions concentration due to the higher asymmetry around Eu3+ ions. Further, emission intensities were characterized using CIE chromaticity diagram and the (x,y) chromaticity coordinates (0.63, 0.36) suggests the pure intense red emission obtained from the prepared glasses useful for laser applications at 616 nm.

Development of sodium-zinc phosphate glasses doped with Dy3+, Eu3+ and Dy3+/Eu3+ for yellow laser medium, reddish-orange and white phosphor applications

A spectroscopy analysis of Eu2O3 (2.0mol%) or Dy2O3 (2.0mol%) singly-doped and Dy2O3 (2.0mol%)/Eu2O3 (2.0mol%) codoped sodium-zinc phosphate glasses is performed through their Raman, absorbance and photoluminescence spectra, and decay times. The phonon energy (1124cm−1) and electron–phonon coupling strength (0.028) of the glass host were determined using phonon side band spectroscopy. Laser parameter values (stimulated emission cross section, effective bandwidth, gain bandwidth and optical gain), obtained for the 4F9/2 → 6H13/2 yellow emission of the Dy3+ singly-doped glass, are higher than those reported for others 2mol% Dy2O3-doped oxide glasses, so that the magnitudes of such parameters could be suitable for a low threshold and a high gain of yellow laser emission. Additionally a value of the quantum efficiency close to the unity (0.96) was found for the dysprosium 4F9/2 level luminescence. The intense yellow emission relative to the 4F9/2 → 6H15/2 blue one leads to the Dy3+ singly-doped glass to emit neutral white light of 4647K upon 349nm excitation. The Eu3+ singly-doped glass can emit reddish-orange light of 2166K and red color purity of 97.7% upon 394nm excitation, whose (0.642, 0.351) CIE1931chromaticity coordinates are close to those (0.67, 0.33) of the red phosphor proposed by the National Television Standard Committee. The Dy3+/Eu3+codoped glass emission color can be tuned from warm white light of 3628K upon 349nm excitation to reddish-orange light of 1891 K after 364nm excitation. The warm white light emission is generated mainly by the transitions 4F9/2 → 6H13/2, 6H15/2 of Dy3+ and 5D0 → 7F2 of Eu3+, where Eu3+ is sensitized by Dy3+ through non-radiative energy transfer with an efficiency of 0.22. An electric dipole-dipole interaction into Dy3+ - Eu3+ clusters might be the dominant mechanism in the Dy3+ to Eu3+ energy transfer. Excitations at 349, 364 and 394nm can be obtained with AlGaN, GaN and InGaN based LEDs, respectively, and therefore Dy3+ and/or Eu3+ doped sodium-zinc phosphate glasses pumped by UV LEDs could be appropriate for solid state lighting technology as neutral/warm white and reddish-orange light sources.

A closer look on the coordination of soft nitrogen-donor ligands to Cm(iii): SO3-Ph-BTBP.

We present a combined theoretical and experimental study on the recently developed hydrophilic SO3-Ph-BTBP ligand. Vibronic side band spectroscopy and time-resolved laser fluorescence spectroscopy (TRLFS) were employed to prove the theoretical prediction of the ligand's coordination mode.

Nondestructive imaging of an ultracold lattice gas

We demonstrate the nondestructive imaging of a lattice gas of ultracold bosons. Atomic fluorescence is induced in the simultaneous presence of degenerate Raman sideband cooling. The combined influence of these processes controllably cycles an atom between a dark state and a fluorescing state while eliminating heating and loss. Through spatially resolved sideband spectroscopy following the imaging sequence, we demonstrate the efficacy of this imaging technique in various regimes of lattice depth and fluorescence acquisition rate. Our work provides an important extension of quantum gas imaging to the nondestructive detection, control and manipulation of atoms in optical lattices. In addition, our technique can also be extended to atomic species that are less amenable to molasses-based lattice imaging.

Micro-fabricated stylus ion trap

An electroformed, three-dimensional stylus Paul trap was designed to confine a single atomic ion for use as a sensor to probe the electric-field noise of proximate surfaces. The trap was microfabricated with the UV-LIGA technique to reduce the distance of the ion from the surface of interest. We detail the fabrication process used to produce a 150 μm tall stylus trap with feature sizes of 40 μm. We confined single, laser-cooled, (25)Mg(+) ions with lifetimes greater than 2 h above the stylus trap in an ultra-high-vacuum environment. After cooling a motional mode of the ion at 4 MHz close to its ground state (<n> = 0.34 ± 0.07), the heating rate of the trap was measured with Raman sideband spectroscopy to be 387 ± 15 quanta/s at an ion height of 62 μm above the stylus electrodes.

Precise Experimental Investigation of Eigenmodes in a Planar Ion Crystal

The accurate characterization of eigenmodes and eigenfrequencies of two-dimensional ion crystals provides the foundation for the use of such structures for quantum simulation purposes. We present a combined experimental and theoretical study of two-dimensional ion crystals. We demonstrate that standard pseudopotential theory accurately predicts the positions of the ions and the location of structural transitions between different crystal configurations. However, pseudopotential theory is insufficient to determine eigenfrequencies of the two-dimensional ion crystals accurately but shows significant deviations from the experimental data obtained from resolved sideband spectroscopy. Agreement at the level of 2.5×10(-3) is found with the full time-dependent Coulomb theory using the Floquet-Lyapunov approach and the effect is understood from the dynamics of two-dimensional ion crystals in the Paul trap. The results represent initial steps towards an exploitation of these structures for quantum simulation schemes.

Cooling a Single Atom in an Optical Tweezer to Its Quantum Ground State

We report cooling of a single neutral atom to its three-dimensional vibrational ground state in an optical tweezer. After employing Raman sideband cooling for tens of milliseconds, we measure via sideband spectroscopy a three-dimensional ground-state occupation of ~90%. We further observe coherent control of the spin and motional state of the trapped atom. Our demonstration shows that an optical tweezer, formed simply by a tightly focused beam of light, creates sufficient confinement for efficient sideband cooling. This source of ground-state neutral atoms will be instrumental in numerous quantum simulation and logic applications that require a versatile platform for storing and manipulating ultracold single neutral atoms. For example, these results will improve current optical tweezer experiments studying atom-photon coupling and Rydberg quantum logic gates, and could provide new opportunities such as rapid production of single dipolar molecules or quantum simulation in tweezer arrays.

Sideband spectroscopy and dispersion measurement in microcavities

The measurement of dispersion and its control have become important considerations in nonlinear devices based on microcavities. A sideband technique is applied here to accurately measure dispersion in a microcavity resulting from both geometrical and material contributions. Moreover, by combining the method with finite element simulations, we show that mapping of spectral lines to their corresponding transverse mode families is possible. The method is applicable for high-Q, micro-cavities having microwave rate free spectral range and has a relative precision of 5.5 × 10(-6) for a 2 mm disk cavity with FSR of 32.9382 GHz and Q of 150 milllion.