Fluctuations Of Experimental Parameters Research Articles

Comparison of different calibration techniques of laser induced breakdown spectroscopy in bakery products: on NaCl measurement

Laser induced breakdown spectroscopy (LIBS) is a rapid optical spectroscopy technique for elemental determination, which has been used for quantitative analysis in many fields. However, the calibration involving atomic emission intensity and sample concentration, is still a challenge due to physical-chemical matrix effect of samples and fluctuations of experimental parameters. To overcome these problems, various chemometric data analysis techniques have been combined with LIBS technique. In this study, LIBS was used to show its potential as a routine analysis for Na measurements in bakery products. A series of standard bread samples containing various concentrations of NaCl (0.025%–3.5%) was prepared to compare different calibration techniques. Standard calibration curve (SCC), artificial neural network (ANN) and partial least square (PLS) techniques were used as calibration strategies. Among them, PLS was found to be more efficient for predicting the Na concentrations in bakery products with an increase in coefficient of determination value from 0.961 to 0.999 for standard bread samples and from 0.788 to 0.943 for commercial products.

Population transfer in a nonlinear three-level Λ-system by Stark - chirped rapid adiabatic passage

We propose the use of the Stark-chirped rapid adiabatic passage (SCRAP) method to induce a complete population transfer in a nonlinear three-level Λ-type system (nl-SCRAP). We also use the nl-SCRAP method for creating stable diatomic ground molecular Bose–Einstein condensates (BECs) from atomic BECs. In this three-laser technique the pump and Stokes pulses are slightly detuned from transition frequencies, and a third strong hyperbolic-tangent laser pulse induces dynamic Stark shifts of the relevant transitions and compensates for third-order nonlinearities. If the timing of the three pulses is appropriately chosen, the nonlinear quantum system is prepared to almost complete population inversion between the two lower states in the Λ-like scheme. The paper shows that the efficiency of the nl-SCRAP is higher than the nonlinear stimulated Raman adiabatic passage (nl-STIRAP) technique, and this method can be used in one-photon as well as multi-photon transitions. The transfer process is robust concerning fluctuations of experimental parameters, such as peak Rabi frequencies, the time delay between pulses, and static detunings.

Long-Term Stability Analysis Toward

Long-term frequency instabilities in vapor-cell clocks mainly arise from fluctuations of the experimental and environmental parameters that are converted to clock frequency fluctuations via various physical processes. Here, we discuss the frequency sensitivities and the resulting stability limitations at one-day timescale for a rubidium vapor-cell clock based on a compact magnetron-type cavity operated in air (no vacuum environment). Under ambient laboratory conditions, the external atmospheric pressure fluctuations may dominantly limit the clock stability via the barometric effect. We establish a complete long-term instability budget for our clock operated under stable pressure conditions. Where possible, the fluctuations of experimental parameters are measured via the atomic response. The measured clock instability of at one day is limited by the intensity light-shift effect, which could further be reduced by active stabilization of the laser intensity or stronger optical pumping. The analyses reported here show the way toward simple, compact, and low-power vapor-cell atomic clocks with excellent long-term stabilities ≤ 10-14 at one day when operated in ambient laboratory conditions.

Fast quantum state engineering via universal SU(2) transformation

We introduce a simple yet versatile protocol to inverse engineer the time-dependent Hamiltonian in two- and three level systems. In the protocol, by utilizing a universal SU(2) transformation, a given speedup goal can be obtained with large freedom to select the control parameters. As an illustration example, the protocol is applied to perform population transfer between nitrogen-vacancy (NV) centers in diamond. Numerical simulation shows that the speed of the present protocol is fast compared with that of the adiabatic process. Moreover, the protocol is also tolerant to decoherence and experimental parameter fluctuations. Therefore, the protocol may be useful for designing an experimental feasible Hamiltonian to engineer a quantum system.

Single-shot nonlinear spectroscopy in the vacuum-ultraviolet

Time-resolved spectroscopy in the vacuum/extreme ultraviolet (VUV/XUV) spectral range promises to disclose ultrafast dynamics in all states of matter. Completing a measurement within a single shot eliminates the influence of experimental parameter fluctuations and enhances its statistical significance. We demonstrate a single-shot temporal metrology scheme operating in the vacuum/extreme-ultraviolet spectral range, combining few-femtosecond resolution in a wide temporal window with high detection efficiency. An anticollinear geometry encodes temporal delay information on the beam propagation coordinate. The spatial distribution of ions created in the common focus is captured with a mass/charge-state-selective ion imaging spectrometer, resulting in a single-shot pump–probe measurement. We demonstrate a proof-of-principle single-shot VUV-pump/VUV-probe experiment by investigating ultrafast dissociation dynamics of O2 excited at 162 nm. The experimental determination of the finite instrument response in the same apparatus enables robust deconvolution of the investigated dynamics well beyond the instrument’s intrinsic temporal resolution.

Adiabatic Generation of N-quNit Singlet States with Cavity QED

We present a theoretical scheme to generate N-quNit singlet states with N 3 via adiabatic passage. In this protocol, the system may be robust against both experimental parameter fluctuations and dissipations along dark states. In addition, during the whole procedure, quantum information is almost fully transferred between atomic ground states. It reduces the influence of dissipations such as atomic spontaneous emissions and cavity decays. Thus, the presented proposal may be feasible based on current technologies.

Improving the stimulated Raman adiabatic passage via dissipative quantum dynamics.

We propose a method to improve the stimulated Raman adiabatic passage (STIRAP) via dissipative quantum dynamics, taking into account the dephasing effects. Fast and robust population transfer can be obtained with the scheme by the designed pulses and detuning, even though the initial state of the system is imperfect. With a concrete three-level system as an example, the influences of the imperfect initial state, variations in the control parameters, and various dissipation effects are discussed in detail. The numerical simulation shows that the scheme is insensitive to moderate fluctuations of experimental parameters and the relatively large dissipation effects of the excited state. Furthermore, the dominant dissipative factors, namely, the dephasing effects of the ground states and the imperfect initial state are no longer undesirable, in fact, they are the important resources to the scheme. Therefore, the scheme could provide more choices for the realization of the complete population transfer in the strong dissipative fields where the standard stimulated Raman adiabatic passage or shortcut schemes are invalid.

Study on quantitative analysis of slag based on spectral normalization of laser-induced plasma image

To reduce the influence of laser-induced breakdown spectroscopy (LIBS) experimental parameter fluctuations to quantitative analysis of slag components, a normalization method using integral intensity of plasma image was proposed and a series of experiments with slag samples were performed. Mg II 279.55 nm, Ca II 396.85 and Ca I 422.67 nm were selected as analytical lines, and analytical curves of reference mass fractions versus spectral line intensities were established. With the increment of set threshold for edge extraction of plasma image, the determination coefficients and relative standard deviations of analytical curves were improved gradually and reached the optimum values when the threshold was equal to 10 000. Comparing with the results without normalization and normalized by whole spectrum area, the relativity between spectral line intensity and mass fraction can be enhanced efficiently after normalized by integral intensity of plasma image. The verification experiments with Ti alloy samples further confirmed the conclusions mentioned above.

Generation of steady three- and four-dimensional entangled states via quantum-jump-based feedback

A scheme is presented for generating steady three- (four-) dimensional entangled states for two atoms trapped in a strongly dissipative single-mode (double-mode) cavity via quantum-jump-based feedback. The cavity decay is no longer undesirable, but plays an integral part in the schemes. Numerical results show that the target states could be obtained from any initial states via quantum-jump-based feedback. Moreover, our scheme is insensitive to moderate fluctuations of experimental parameters and detection inefficiencies without atomic decay since the system can always reach the target state. Nevertheless, the atomic decay still plays a negative role in the current scheme. The scheme can be generalized to realize $$N$$ -dimensional entanglement for two atoms.

Deterministic generation of Greenberger-Horne-Zeilinger and W states for three distant atoms via adiabatic passage

We propose two schemes for generating Greenberger-Horne-Zeilinger and W states of three distant atoms. In the present schemes, the atoms are individually trapped in three spatially separated optical cavities coupled by two optical fibres. Performing an adiabatic passage along dark states, the population of cavities and fibres excited is negligible under certain conditions. In addition, the spontaneous decay of atoms is also efficiently suppressed based on our proposals. Furthermore, the discussion about the entanglement fidelity is given and we point out that our schemes work robustly with small fluctuations of experimental parameters.

Quantitative determination of element concentrations in industrial oxide materials by laser-induced breakdown spectroscopy

Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) method is employed for quantitative determination of oxide concentrations in multi-component materials. Industrial oxide materials from steel industry are laser ablated in air, and the optical plasma emission is collected by spectrometers and gated detectors. The temperature and electron number density of laser-induced plasma are determined from measured LIBS spectra. Emission lines of aluminium (Al), calcium (Ca), iron (Fe), manganese (Mn), magnesium (Mg), silicon (Si), titanium (Ti), and chromium (Cr) of low self-absorption are selected, and the concentration of oxides CaO, Al(2)O(3), MgO, SiO(2), FeO, MnO, TiO(2), and Cr(2)O(3) is calculated by CF-LIBS analysis. For all sample materials investigated, we find good match of calculated concentration values (C(CF)) with nominal concentration values (C(N)). The relative error in oxide concentration, e(r) = |C(CF) - C(N)|/C(N), decreases with increasing concentration and it is e(r) ≤ 100% for concentration C(N) ≥ 1 wt.%. The CF-LIBS results are stable against fluctuations of experimental parameters. The variation of laser pulse energy over a large range changes the error by less than 10% for major oxides (C(N) ≥ 10 wt.%). The results indicate that CF-LIBS method can be employed for fast and stable quantitative compositional analysis of multi-component materials.

Entanglement of separate nitrogen-vacancy centers coupled to a whispering-gallery mode cavity

We present a quantum electrodynamical model involving nitrogen-vacancy centers coupled to a whispering-gallery mode cavity. We consider two schemes to create the W state and Bell state, respectively. One scheme makes use of Raman transition with the cavity field virtually excited, and the other enables Bell state preparation and quantum information transfer by virtue of dark state evolution and adiabatic passage, which is tolerant to ambient noise and experimental parameter fluctuations. We justify our schemes by considering their experimental feasibility and challenge, using the currently available technology.

Stark-chirped rapid adiabatic passage among a three-state molecular system: Experimental and numerical investigations

We present extended experimental investigations and numerical studies on coherently driven population inversion in a three-state molecular quantum system by sequential double-Stark-chirped rapid adiabatic passage (SCRAP) (D-SCRAP) and three-state-SCRAP (T-SCRAP). D-SCRAP and T-SCRAP are alternative extensions of SCRAP. In D-SCRAP and T-SCRAP, a $\ensuremath{\Lambda}$-type quantum system is coherently driven by two laser pulses, the pump and Stokes pulses, which are slightly detuned from transition frequencies. A third strong laser pulse induces dynamic Stark shifts of the relevant transitions. If the timing of the three pulses is appropriately chosen, the quantum system is prepared to almost complete population inversion between the two lower states in the $\ensuremath{\Lambda}$-type level scheme. The transfer process is robust with regard to fluctuations of experimental parameters, provided some limitations are met. The paper presents convincing experimental data on D-SCRAP and T-SCRAP, driving efficient and selective population transfer to a highly excited vibrational level in nitrous oxide (NO) molecules. T-SCRAP yields transfer efficiencies of up to 95%. The efficiency of T-SCRAP is almost uneffected by the limited lifetime of the intermediate state in the $\ensuremath{\Lambda}$ system. The paper also presents data on the accurate experimental determination of Rabi frequencies and Stark shifts. This involves measurements of power broadening, Autler-Townes splittings, and Stark-shifted spectral lines in NO molecules. Moreover, we discuss the calibration of absolute transfer efficiences by comparison with stimulated emission pumping. The experimental data are confirmed by extended numerical simulations. The simulations also serve to intensively study the properties and dynamics of D-SCRAP and T-SCRAP.

Deterministic geometric quantum phase gates for two atoms in decoherence-free subspace

We propose a scheme for realizing conventional geometric quantum phase gates in the context of cavity QED. During the operation neither the atomic system nor the cavity mode is excited, which is important in view of decoherence. The scheme does not require detection of photons, so the gate operation is deterministic and the influence of photodetection imperfection is eliminated. Taking advantage of the geometric manipulation, the phase gate is resilient to fluctuations of experimental parameters.

Entanglement and Phase-Covariant Cloning for Multiple Trapped Ions via Adiabatic Passage

We describe a scheme for the generation of W states and implementation of phase-covariant cloning for n trapped ions. The scheme does not use the vibational mode as the memory and works beyond the Lamb-Dicke regime. The procedure is robust against moderate fluctuations of experimental parameters by using adiabatic passage.

ENTANGLEMENT GENERATION AND CONCENTRATION VIA ADIABATIC EVOLUTION WITH TRAPPED IONS

We propose two schemes via adiabatic evolution of dark eigenstates in an ion trap system. One is an entanglement generation of multi-ion cluster states, the other is entanglement concentration via entanglement swapping. Our schemes are robust against moderate fluctuations of experimental parameters since we utilize the adiabatic passage in the main procedure. The current idea can be generalized to other systems.

Quantum Phase Gates for Trapped Ions via AdiabaticPassage

We propose a scheme to produce quantum phase gates for trapped ions.Taking advantage of the adiabatic evolution, the operation is insensitive tosmall fluctuations of experimental parameters. Furthermore, the spontaneousemission is suppressed since the ions have no probability of being populatedin the electronic excited states.

Nongeometric Conditional Phase Shift via Adiabatic Evolution of Dark Eigenstates: A New Approach to Quantum Computation

We propose a new approach to quantum phase gates via the adiabatic evolution. The conditional phase shift is neither of dynamical nor geometric origin. It arises from the adiabatic evolution of the dark state itself. Taking advantage of the adiabatic passage, this kind of quantum logic gates is robust against moderate fluctuations of experimental parameters. In comparison with the geometric phase gates, it is unnecessary to drive the system to undergo a desired cyclic evolution to obtain a desired solid angle. Thus, the procedure is simplified, and the fidelity may be further improved since the errors in obtaining the required solid angle are avoided. We illustrate such a kind of quantum logic gates in the ion trap system. The idea can also be realized in other systems, opening a new perspective for quantum information processing.

Qubit rotation by stimulated Raman adiabatic passage

We introduce a novel procedure for qubit rotation, alternative to the commonly used method of Rabi oscillations of controlled pulse area. It is based on the technique of Stimulated Raman Adiabatic Passage (STIRAP) and therefore it is robust against fluctuations of experimental parameters. Furthermore, our work shows that it is in principle possible to perform quantum logic operations via stimulated Raman adiabatic passage. This opens up the search for a completely new class of schemes to implement logic gates.