Ion Trap Mass Spectrometer Research Articles

Protein Identification Improvement in Complex Samples Using Higher Frequency MS Acquisition and PEAKS Software

Protein identification in complex biological samples using the shotgun mode of LC-MS/MS is typically enhanced by employing longer LC columns and extended gradient times. However, improved identification rates can also be achieved by optimizing MS acquisition frequencies and employing advanced software, without increasing analysis time, thus maintaining the throughput of the method. To date, we found only one study in the literature examining the influence of MS acquisition frequency on protein identification, specifically using two ion trap mass spectrometer models. This study aims to address the gap by analyzing the impact of MS acquisition tuning of the QTOF instrument on the analysis of complex samples. Our findings indicate that increasing acquisition frequency generally improves protein identification, although the extent of improvement depends on the sample type. For CHO cell lysates, protein identifications increased by over 10%, while E. coli and albumin-depleted plasma samples demonstrated gains of 3.6% and 2.6%, respectively. Higher contributions to protein identification were also achieved with extended LC gradients, resulting in improvements of 21.6% for CHO, 18.2% for E. coli, and 10.3% for plasma. Moreover, enabling PEAKS’ deep learning feature significantly boosted identifications, with increases of 22.9% for CHO, 23.2% for E. coli, and 9.2% for plasma.

Discrimination of Healthy and Botrytis cinerea-Infected Grapes Using Untargeted Metabolomic Analysis with Direct Electrospray Ionization Mass Spectrometry.

Botrytis cinerea infections of grapes significantly reduce yield and quality and increase phenolic compound oxidation, resulting in color loss, off-flavors, and odors in wine. In this study, metabolites were extracted from grape homogenates comprising healthy or infected grapes from different vintages, cultivars, regions, and maturity stages. Samples were randomly analyzed by direct injection into an ion trap mass spectrometer, with data collected from 50 to 2000 m/z for 1 min. Molecular feature abundances from 0.1 to 0.4 min were normalized prior to Principal Components Analysis assessment of workflow. Samples were randomly assigned to a calibration and independent test sample set, with feature reduction, a two-class model Partial Least Squares-Discriminant Analysis, cross-validation, and permutation testing performed with the calibration data set. Prediction of sample class in the independent test samples demonstrated an overall predictive error of less than 5%. Feature importance was assessed using a combined variable importance in projection and selectivity ratio plot. Annotation of important molecular features using a high-resolution LC-QTOF mass spectrometry MS/MS of selected samples enabled key metabolites palmitic, oleic, linoleic and linolenic acids, succinate, and epicatechin to be identified and associated with infection. The proposed workflow establishes sensitive high-throughput rapid MS-based methods for phytosanitary testing of grape and fruit samples.

Direct Implementation of MSn Using Frequency Scanning Collision Induced Dissociation in a Digital Ion Trap Mass Spectrometer.

Tandem mass spectrometry (MSn) is one of the most effective methods to obtain the structures of organic molecules, enabling the observation of multigenerational ion fragments. Collision-induced dissociation (CID) is currently the most mature technique for mass spectrometry analysis. Ion trap mass spectrometry (ITMS) is favored for on-site detection field, due to its ability of MSn analysis with a single trap and its small size. However, conventional MSn analysis in ITMS requires repeated isolation and excitation processes multiple times, causing high complexity of the entire scanning process. Additionally, the fragment ion detection in ITMS is limited by low-mass cutoff (LMCO) and the weak fragmentation yield. In this study, a method named reverse scanning-collision induced dissociation (RS-CID) is proposed, which involves increasing RF and AC frequencies while maintaining RF voltage constant during the CID process. Twelve representative illegal drugs were analyzed adopting this method, enhancing the intensities of low-mass fragment ions compared to conventional dissociation method. Moreover, experimental results with ketamine and methamphetamine show that RS-CID effectively reduces the LMCO effect and slightly improves CID efficiency. It also enables direct acquisition of their multigeneration fragment ions spectra in a single sequence of ion injection, cooling, isolation, RS-CID, cooling, mass scanning and empty. The experiments to distinguish between the isomers ab-4en-pinaca and adb-3en-butinaca as well as the isomeric compounds 5f-cumyl-pegaclone and cumyl-pipetinaca were also successful by this method. In summary, RS-CID enables MSn analysis in a single sequence and improves the low-mass fragment ions intensity. It can simplify workflows, achieve faster analysis and provide more valuable mass spectral information.

Rotational Locking of Charged Microparticles in Quadrupole Ion Traps

Rotational Locking of Charged Microparticles in Quadrupole Ion Traps

Establishment of a Mass Spectrometric Fingerprint of the Most Common Phytocannabinoids in Electrospray Ionization in Positive Ion Mode.

Analysis of the phytocannabinoids holds significant importance because of their various pharmacological properties and potential therapeutic applications. Tandem mass spectrometry (MS/MS) coupled with electrospray ionization in positive ion mode is employed in this study to describe the collision-induced dissociation (CID) behavior of a series of common phytocannabinoids with the aim of establishing a generalized MS/MS fingerprint. Eight phytocannabinoids, namely, ∆9-tetrahydrocannabinol (THC), cannabidiol (CBD), cannabichromene (CBC), cannabigerol (CBG), tetrahydrocannabivarin (THCV), 11-hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC), 6-hydroxy-cannabidiol (6-OH-CBD), and 7-hydroxy-cannabidiol (7-OH-CBD), were studied. A Quadrupole-Orbitrap mass spectrometer equipped with a heated electrospray ionization (HESI-Q Orbitrap) is used to provide accurate mass measurement data for single-stage and MS/MS analysis. In addition, a triple quadrupole-linear ion trap mass spectrometer was used to perform MS/MS and second-generation MS/MS (MS3) analyses. An abundant, singly charged [M + H]+ species during single-stage MS analysis was observed for all phytocannabinoids, with mass accuracies less than 5 ppm. Because of their structural similarities, all compounds showed some common fragmentation behavior in their MS/MS analysis. By comparing the fragmentation patterns and identifying diagnostic ions, a universal MS/MS fragmentation pattern was established. The structures of the various product ions proposed in the fragmentation pathway were confirmed with exact mass measurements and MS3 experiments. The evaluated compounds contain varying functional groups, resulting in unique product ions, specific to each structure. The MS/MS fingerprints will be utilized in the future for the identification of new structures as well as the development of targeted quantification methods.

Qualitative screening of emerging contaminants in urban and natural waters of Mangaung District of the Free State province of South Africa

Chemicals enable the development of new technologies while also raising living standards and quality of life. Although chemicals are used in many aspects of daily life, such as the advance of innovative technologies and the improvement of living values, many of them are discharged into the aqueous environment which may lead to negative environmental health effects such as endocrine disorders, reduced reproductive rates, reduced life expectancy and insomnia. In this study, a high performance liquid chromatography connected to hybrid triple quadrupole ion trap mass spectrometer was used for qualitative non-target screening of emerging contaminants in water sources. The analytes were detected in five rivers, five dams, three wastewater treatment works and two drinking water treatment plants. The qualitative screening of emerging contaminants in these urban and natural water sources revealed 32 analytes under pharmaceutical and pesticide groups. From these groups, stimulants and herbicides were the most dominant. Among the analytes found in urban and natural waters of Mangaung District, three stimulants (ephedrine, nicotine, and metformin) and two herbicides (terbuthylazine, and sebuthylazine) were mostly detected. High number of these analytes (diphenhydramine, orphenadrine, cyclicine, paracetamol, sulfamethoxazol, metformin, bezafibrate, lamivudine, THC-COOH, methamphetamine, nicotine, ephedrine, theophylline, hordenine, sebuthylazine, atrazine, simazine, terbuthylazine, metolachlor, carbendazim, diazinon, and simazine) was observed in river samples and least in treated drinking water. Most notable was the detection of terbuthylazine in all samples collected in dams, effluent and treated drinking water. The ubiquitous presence of terbuthylazine in water sources may possibly lead to some environmental health risks. The findings of this study may be used for target analysis of these chemicals in future monitoring and risk assessment studies in the Free State region, where emerging contaminants research is limited. Furthermore, it may assist water managers and policymakers in assessing water quality and managing pollution more effectively.

Creation of Gas-Phase Organo-Uranium Species by Removal of "yl" Oxo Ligands From UO2 2+ Carboxylate Precursor Ions.

These experiments were conducted to measure the diversity of organo-U (IV) and U (III) ions created using multiple-stage tandem MS and collision-induced dissociation of halogen-substituted UVIO2-phenide complexes [UO2(C6H3FX)]+, X = Cl, Br, or I. Samples of UO2(O2C-C6H3FX)2 were prepared by digesting UO3 with appropriate halogen-substituted carboxylic acids in deionized water. Solutions for ESI were created by diluting the digested sample in 50:50 H2O/CH3OH. Precursor ions for multiple-stage tandem MS were generated by electrospray ionization (ESI). Multiple-stage collision-induced dissociation (He collision gas) in a linear quadrupole ion trap mass spectrometer was used to prepare species such as [UIVFX(C≡CH)]+ and UIIIF(C≡CH)]+ for subsequent study of ion-molecule reactions with adventitious neutrals in the ion trap. Multiple-stage CID of the [UO2(C6H3FX)]+, X = Cl, Br, or I, complexes caused removal of both "yl" oxo ligands from of the UO2 2+ moiety to create ions such as [UIVFX(C≡CH)]+ and [UIIIFX]+. For [UIVFXC≡CH]+ and [UIIIFC≡CH]+ products, hydrolysis to generate [UIVFX (OH)]+ and [UIIIF (OH)]+, with concomitant loss of HC≡CH, was observed. CID of [UO2(C6H3FBr)]+ and [UO2(C6H3FI)]+ caused reductive elimination of the respective halogen radicals to generate interesting organo-U (III) species such as [UIIIF(C≡CH)]+ and [UIIIC2]+. The use of "preparative" tandem mass spectrometry and a suite of halogen substituted benzoic acid ligands can be used to remove both oxo ligands of UO2 2+ and generate a group of homologous organo-U (IV) and organo-U (III) ions for studies of intrinsic reactivity.

Electron Transfer Dissociation of Alkali-Cationized Phosphatidylcholines Allows Easy Double Bonds and sn-1/sn-2 Localizations.

The emergence of new mass spectrometry (MS) dissociation methods has highlighted lipid isomers as new biomarkers. Only a few commercial methods without derivatization are available to characterize phosphatidylcholines (PCs) at the isomeric level. We propose to use electron transfer dissociation (ETD) as a method to determine the position of both double bonds and stereo numbering (sn) on glycerol for PC species. Doubly charged PCs were analyzed using alkali salts to promote the formation of [PC + 2Alk]2+ species. ETD-MS2 experiments were performed using a quadrupole ion trap mass spectrometer with an ESI source to annotate sn-positions. ETD-CID-MS3 experiments were then done on ETnoD [M + 2Alk]+• or [M + 2Alk-N(CH3)3]+• species to localize double bond positions. Density functional theory (DFT) calculations and cyclic ion mobility spectrometry c-IMS-MS/MS experiments were used to support fragmentation assumptions. ETD-MS2 experiments exhibit a systematic sn-2 favorable cleavage, allowing sn-positioning through a radical cation-driven mechanism supported by DFT calculations. This behavior contrasts with CID experiments, in which the initial positioning of alkali cations influences ester bond cleavage, as shown by c-IMS-MS/MS experiments. The dissociation process studied for ETD-CID-MS3 experiments on 10 different PC isomers allowed us to localize double bonds for either monounsaturated or polyunsaturated species. The dissociation rules established for ETD-MS2 and ETD-CID-MS3 experiments on PC isomers enable their annotation at the isomeric level without instrumental modification or complex sample preparation. This method could be easily coupled to LC separation using post-column introduction of an alkali salt for complex mixture analysis.

Energy-Resolved Mass Spectrometry and Mid-Infrared Spectroscopy for Purity Assessment of a Synthetic Peptide Cyclised by Intramolecular Huisgen Click Chemistry.

Cyclic peptides have higher stability and better properties as therapeutic agents than their linear peptide analogues. Consequently, intramolecular click chemistry is becoming an increasingly popular method for the synthesis of cyclic peptides from their isomeric linear peptides. However, assessing the purity of these cyclic peptides by mass spectrometry is a significant challenge, as the linear and cyclic peptides have identical masses. In this paper, we have evaluated the analytical capabilities of energy-resolved mass spectrometry (ER MS) and mid-infrared microscopy (IR) to address this challenge. On the one hand, mixtures of both peptides were subjected to collision-induced dissociation tandem mass spectrometry (CID MS/MS) experiments in an ion trap mass spectrometer at several excitation energies. Two different calibration models were used: a univariate model (at a single excitation voltage) and a multivariate model (using multiple excitation voltages). The multivariate model demonstrated slightly enhanced analytical performance, which can be attributed to more effective signal averaging when multiple excitation voltages are considered. On the other hand, IR microscopy was used for the quantification of the relative amount of linear peptide. This was achieved through univariate calibration, based on the absorbance of an alkyne band specific to the linear peptide, and through Partial Least Squares (PLS) multivariate calibration. The PLS calibration model demonstrated superior performance in comparison to univariate calibration, indicating that consideration of the full IR spectrum is preferable to focusing on the specific peak of the linear peptide. The advantage of IR microscopy is that it is linear across the entire working interval, from linear peptide molar ratios of 0 (equivalent to pure cyclic peptide) up to 1 (pure linear peptide). In contrast, the ER MS calibration models exhibited linearity only up to 0.3 linear peptide molar ratio. However, ER MS showed better performances in terms of the limit of detection, intermediate precision and the root-mean-square-error of calibration. Therefore, ER MS is the optimal choice for the detection and quantification of the lowest relative amounts of linear peptides.

Integration of ion mobility-quadrupole time-of-flight mass spectrometry and triple quadrupole-ion trap mass spectrometry coupled with ultra-high performance liquid chromatography for characterizing and quantitatively assay the saponins of Panax quinquefolius flower

Panax quinquefolius (American ginseng) is globally popular serving as herbal medicine or tonifying agent. Compared with the root, studies on the flower of Panax quinquefolius (PQF) in respect of the multicomponent characterization and quality evaluation is scarce. This work was designed, by feat of two liquid chromatography–mass spectrometry platforms, to characterize and quantitatively assay the saponins of PQF. Ultra-high performance liquid chromatography/ion mobility-quadrupole time-of-flight mass spectrometry (UHPLC/IM-QTOF-MS) combined with data-independent high-definition MSE (HDMSE) was developed to acquire the structure information of PQF saponins. Consequently, efficient and more accurate identification (higher identification accuracy and much lower false positives rate) of the involved saponins were accomplished by the intelligent peak annotation workflows of the UNIFI bioinformatics platform incorporated with a “Multi-dimensional Information Library of Ginsenosides” (GinMIL). Totally 128 ginsenosides were identified or tentatively characterized, and 45 thereof were identified by comparing with the reference standards. Additionally, an efficient UHPLC/QTrap-MS (triple quadrupole-ion trap mass spectrometry) method enabling quantitative assay of 21 ginsenosides in PQF was established and validated by scheduled multiple reaction monitoring (sMRM). It gave low limit of detection (0.011–0.65 pg) and limit of quantification (0.053–4.1 pg), good linearity (R2 > 0.99), intra-/inter-day precision (RSD < 13.6 %), stability (RSD < 3.5 %), repeatability (RSD < 7.5 %), and recovery (RSD < 13.5 %). It application to quantify 21 ginsenosides in 14 batches of PQF samples revealed differences in their saponin content. Conclusively, systematic multi-component characterization and multi-indicator quantitation of PQF were achieved, thus providing the methodological reference for the quality investigation of functional herbs.

Infrared Photoactivation Enables nano-DESI MS of Protein Complexes in Tissue on a Linear Ion Trap Mass Spectrometer.

Native mass spectrometry analysis of proteins directly from tissues can be performed by using nanospray-desorption electrospray ionization (nano-DESI). Typically, supplementary collisional activation is essential to decluster protein complex ions from solvent, salt, detergent, and lipid clusters that comprise the ion beam. As an alternative, we have implemented declustering by infrared (IR) photoactivation on a linear ion trap mass spectrometer equipped with a CO2 laser (λ = 10.6 μm). The prototype system demonstrates declustering of intact protein complex ions up to approximately 50 kDa in molecular weight that were sampled directly from brain and eye lens tissues by nano-DESI. For example, signals for different metal binding states of hSOD1G93A homodimers (approximately 32 kDa) separated by only approximately 6 Th (10+ ions) were resolved with IR declustering, but not with collisional activation. We found IR declustering to outperform collisional activation in its ability to reduce chemical background attributable to nonspecific clusters in the nano-DESI ion beam. The prototype system also demonstrates in situ native MS on a low-cost mass spectrometer and the potential of linear ion trap mass spectrometers for this type of analysis.

Nuclear Magnetic Resonance with a Levitating Microparticle.

Nuclear magnetic resonance (NMR) spans diverse fields from biology to quantum science. Employing NMR on a floating object could unveil novel possibilities beyond conventional operational paradigms. Here, we observe NMR within a levitating microdiamond using the nuclear spins of nitrogen-14 atoms. By tightly confining the angular degrees of freedom of the diamond in a Paul trap, we achieve efficient hyperfine interaction between optically polarized electronic spins of nitrogen-vacancy centers and the ^{14}N nuclear spin, enabling nuclear spin polarization and quantum state readout revealing coherence times up to hundreds of microseconds. This represents the longest recorded spin coherence time in a levitated system, surpassing previous records by 3 orders of magnitude. Our results offer promise for various applications, including cooling macroscopic particles to their motional ground state and exploring geometric phases for gyroscopy.

Toward the Rational Design of an OsM4 Center for Methane Activation: Gas-Phase Result-Derived Neural Network Model.

Gas-phase reactions of [OsBx]+ (x = 1-4) with methane at ambient temperature have been studied by using quadrupole-ion trap mass spectrometry combined with quantum chemical calculations. The [OsBx]+ (x = 1-4) cluster ions can undergo dehydrogenation reactions with methane. Comprehensive analysis of the [OsBx]+/CH4 (x = 1-4) system with Os-complexes ([OsCy]+ (y = 1-3) and [OsOz]+ (z = 1-3)) shows that the large polarity of the cluster and the high sum of the pair energies between Os and the ligand in the ETS-NOCV combine to promote the ability of the cluster to activate methane. Cluster polarity may induce heterolytic cleavage of the C-H bond, and the sum of the pair energies of the fragments may reduce the cluster orbital energy to match the methane orbital and improve the cluster stability. The synergistic interplay of these two factors may offer a viable approach for the activation of methane in the condensed phase, which involves modulating the coordination environment of the active sites to enhance the stability and facilitate C-H bond cleavage and the degree of matching with methane orbitals. A nonlinear function is used to extract second-order characteristic features that have a significant impact on the energy difference based on the limited energy difference data of the OsBmCnOlHk units. A neural network model is next designed to predict the reaction barrier for methane conversion by OsM4+ (M = C, N, O, Al, Si, or P) with high accuracy.

Multi-omics joint analysis reveals the mechanism underlying Chinese herbal Yougui Pill in the treatment of knee osteoarthritis

Ethnopharmacological relevanceYougui Pill (YGP), originating from Jingyue Quanshu, comprises 10 traditional Chinese medicines (TCMs). This classic prescription is renowned for its ability to tonify the kidney, warm the kidney, promote yang, warm the interior, and dispel cold. YGP has proven effective in treating degenerative knee arthritis, osteoporosis, delayed fracture healing, and other orthopedic conditions, making it a widely used clinical prescription for knee osteoarthritis (KOA).Aim of the study: Although YGP is commonly used in clinical practice, its pharmacodynamic material basis and anti-arthritis mechanisms remain unclear. This study aims to comprehensively analyze the chemical constituents of YGP and elucidate its anti-arthritis mechanisms. Materials and methodsUltra-high performance liquid chromatography coupled with electrospray ionization-triple quadrupole-linear ion trap mass spectrometry(ESI-Q TRAP-MS/MS) was used to identify the chemical constituents of YGP. The Hulth method was utilized to establish KOA rat model, and pathological examinations were performed to assess the anti-arthritis effects of YGP. Integrated metabolomics and transcriptomics analyses were conducted to explore the anti-arthritis mechanisms of YGP. Key targets were confirmed via immunohistochemistry. ResultsA total of 1981 chemical components were identified in YGP, predominantly phenolic acids and flavonoids. Compared with the model group, 422 differentially expressed metabolites and 214 differentially expressed genes were identified, primarily involving the MAPK signaling pathway, FoxO signaling pathway, and PI3K-Akt pathway. YGP exerted an anti-osteoarthritis effect by inhibiting the excessive activation of the EGFR/ERT/FOS signaling pathway. ConclusionsTCM offers significant advantages in the treatment of KOA, addressing the shortcomings of current clinical medications. YGP displayed exceptional pharmacodynamic effects. This study elucidated its pharmacodynamic material basis and anti-osteoarthritis mechanisms, providing substantial support for its clinical application and the development of related drugs.

Hybrid Paul-optical trap with large optical access for levitated optomechanics

We present a hybrid trapping platform that allows us to levitate a charged nanoparticle in high vacuum using either optical fields, radio-frequency fields, or a combination thereof. Our hybrid approach combines an optical dipole trap with a linear Paul trap while maintaining a large numerical aperture (0.77 NA). We detail a controlled transfer procedure that allows us to use the Paul trap as a “safety net” to recover particles lost from the optical trap at high vacuum. The presented hybrid platform adds to the toolbox of levitodynamics and represents an important step towards fully controllable “dark” potentials, providing control in the absence of decoherence because of photon recoil. Published by the American Physical Society 2024

Simulation of Space Charge Effects in Fourier Transform Quadrupole Ion Traps (FT-QITs).

We present ion dynamics simulations regarding the effect of space charge on the performance of Fourier transform quadrupole ion traps (FT-QITs) with special attention to signal stability, mass resolving power, and sensitivity. Ion trajectory simulations within an idealized QIT geometry are performed by applying a dedicated application (QITSim) using an in-house developed open simulation framework (IDSimF). Image current detection transients are generated by the application and are subsequently transformed into frequency spectra of ion secular motion. Such frequency spectra are the basis for the calculation of mass spectra in FT-QIT instruments. The simulation results are used to assess the extent of space charge induced effects regarding the analytical performance of FT-QIT systems. The simulation results for two Cl+ and seven Xe+ isotope ions exhibit diverse space charge induced phenomena. Most prominently, complete isotope signal fusion, quantitative individual signal suppression, and severe signal distortions are observed even at low absolute numbers of trapped ions. Furthermore, significant shifts of the secular oscillation frequencies occur, even when the signal shape appears to be mostly unaffected and when the frequency separation for trapped ions with different masses is large. This significantly limits the applicability of FT-QIT systems for high resolution mass spectrometry. An increase of the RF amplitude of the trapping field as well as increasing the extent of ion excitation partly mitigate these adverse space charge effects; nevertheless, the usable operational range of the simulated FT-QIT system for analytical applications remains rather narrow.

Optimization of dissociation efficiency in small linear ion trap mass spectrometer

Abstract Small linear ion trap mass spectrometers are often combined with direct ionization mass spectrometry (DIMS) techniques for detection and analysis. However, DIMS is susceptible to the working environment and matrix effects, resulting in reduced sensitivity, which places high demands on the performance of tandem mass spectrometry of small linear ion trap mass spectrometers. Therefore, the effects of vacuum pressure, collision q-value, collision voltage, and collision time on the dissociation efficiency of the ion trap are experimentally explored in this paper to enhance the performance of tandem mass spectrometry for small linear ion trap mass spectrometers. The findings indicate that as the vacuum pressure increases, dissociation efficiency first increases rapidly and then remains stable, and the peak dissociation efficiency of 56% is attained at a vacuum pressure of 0.31 mTorr. Increasing the collision q value, dissociation efficiency first increased slowly, then increased rapidly, and finally remained almost unchanged. When the collision q value was increased from 0.26 to 0.35, dissociation efficiency increased from 9% to 56%. Meanwhile, the maximum collision voltage corresponding to the optimal dissociation efficiency gradually decreases as the collision q value increases. With the increase in collision time, dissociation efficiency increases rapidly and then remains stable. Therefore, studying the factors affecting dissociation efficiency points the way to enhancing the efficacy of tandem mass spectrometry with small linear ion trap mass spectrometers.

Scalable Multispecies Ion Transport in a Grid-Based Surface-Electrode Trap

Quantum processors based on linear arrays of trapped ions have achieved exceptional performance, but scaling to large qubit numbers requires realizing two-dimensional ion arrays as envisioned in the quantum charge-coupled device (QCCD) architecture. Here, we present a scalable method for the control of ion crystals in a grid-based surface-electrode Paul trap and characterize it in the context of transport operations that sort and reorder multispecies crystals. By combining cowiring of control electrodes at translationally symmetric locations in each grid site with the sitewise ability to exchange the voltages applied to two special electrodes gated by a binary input, site-dependent operations can be achieved using only a fixed number of analog voltage signals and a single digital input per site. In two separate experimental systems containing nominally identical grid traps, one using Yb+171−Ba+138 crystals and the other Ba+137−Sr+88, we demonstrate this method by characterizing the conditional intrasite crystal reorder and the conditional exchange of ions between adjacent sites on the grid. Averaged across a multisite region of interest, we measure subquanta motional excitation in the axial in-phase and out-of-phase modes of the crystals following these operations at exchange rates of 2.5 kHz. In this initial demonstration, the logic controlling the voltage exchange occurs in software, but the applied signals mimic a proposed hardware implementation using crossover switches. These techniques can be further extended to implement other conditional operations in the QCCD architecture such as gates, initialization, and measurement. Published by the American Physical Society 2024

Testing continuous spontaneous localization model with charged macromolecules

Abstract In the last decade, a growing interest has been devoted to models of spontaneous collapse of the wavefunction, known also as collapse models. They coherently solve the well-known quantum measurement problem by suitably modifying the Schrödinger evolution. Quantum experiments are now finally within the reach of testing such models (and thus testing the limits of quantum theory). Here, we propose a method based on a two-ions confined in a linear Paul trap to possibly enhance the testing capabilities of such experiments. The combination of an atomic and a macromolecular ion provide a good match for the cooling of the motional degrees of freedom and a non-negligible insight in the collapse mechanism, respectively.

Preliminary characterization of a surface electrode Paul trap for frequency metrology

Preliminary characterization of a surface electrode Paul trap for frequency metrology