Magnetic Trap Research Articles

An experimental platform for levitated mechanics in space

Abstract Conducting experiments in extreme conditions has long been the aim of the levitated mechanics field, as it allows for the investigation of new fundamental physics phenomena. Sending these experiments into the micro-g environment of space has been one such milestone, with multiple proposals calling for such a platform. At the same time, levitated sensors have demonstrated a high sensitivity to external stimuli, such as electric, magnetic and gravitational forces, which will only improve in low-vibrational conditions. This paper describes the development of a technology demonstrator for optical and magnetic trapping experiments in space. Our payload represents the first concrete step towards future missions with aims of probing fundamental physical questions: matter-wave interferometry of nanoparticles to probe the limits of macroscopic quantum mechanics, detection of Dark Matter candidates and gravitational waves to test physics beyond the Standard Model, and accelerometry for Earth-observation.

Simulation of the evaporative cooling of 87Rb133Cs molecules to Bose-Einstein condensation in an electric-assisted magnetic trap

Abstract Cold molecular physics has been the frontier of atomic, molecular and optical physics for over two decades due to the unique and unprecedented applications. We simulate the evaporative cooling of 87Rb133Cs molecules in a modified electric-assisted magnetic trap by decreasing the electric field. When 10-time loading the experimentally available cold RbCs molecules, we would achieve a number N = 811, a temperature T = 21.34 nK, a phase-space density PSD = 2.67 and a number density n = 5.01 × 1012 cm-3 of Bose–Einstein condensation RbCs molecules in 480 ms.

Esculetin inhibited fever, pain, and inflammatory responses via binding to HSC70.

Esculetin inhibited fever, pain, and inflammatory responses via binding to HSC70.

Two-Dimensional Mathematical Models of Strict Plasma Equilibrium in Galatea Magnetic Traps and Numerical Analysis of Stability

Two-Dimensional Mathematical Models of Strict Plasma Equilibrium in Galatea Magnetic Traps and Numerical Analysis of Stability

Enhanced Collisional Losses from a Magnetic Mirror Using the Lenard-Bernstein Collision Operator

Collisions are crucial in governing particle and energy transport in plasmas confined in a magnetic mirror trap. Modern gyrokinetic codes model transport in magnetic mirrors, but some utilize approximate model collision operators. This study focuses on a Pastukhov-style method of images calculation of particle and energy confinement times using a Lenard-Bernstein model collision operator. Prior work on parallel particle and energy balances used a different Fokker-Planck plasma collision operator. The method must be extended in non-trivial ways to study the Lenard-Bernstein operator. To assess the effectiveness of our approach, we compare our results with a modern finite element solver. Our findings reveal that the particle confinement time scales like a exp(a2) using the Lenard-Bernstein operator, in contrast to the more accurate scaling that the Coulomb collision operator would yield a2 exp(a2), where a2 is approximately proportional to the ambipolar potential. We propose that codes solving for collisional losses in magnetic mirrors utilizing the Lenard-Bernstein or Dougherty collision operator scale their collision frequency of any electrostatically confined species. This study illuminates the collision operator’s intricate role in the Pastukhov-style method of images calculation of collisional confinement.

Nondestructive Control of the Rovibrational Ground State of a Single Molecular Hydrogen Ion in a Penning Trap.

In this work, we demonstrate a new method for quantum state control and nondestructive internal quantum state readout of a single HD^{+} ion in the rovibrational ground state in a Penning trap. Furthermore, we demonstrate a measurement of the magnetic trapping field with the same ion to sub-ppb uncertainty. This could enable nondestructive, high-precision spectroscopy of the hyperfine, Zeeman, and rovibrational level structure of single molecular ions. In particular, this technique can be applied to H_{2}^{+} as well as to its antimatter equivalent, H[over ¯]_{2}^{-}, with the potential for high-precision tests of charge-parity-time reversal symmetry beyond current sensitivities [Phys. Scr. T 1995, 423 (1995)PHSTBO0031-894910.1088/0031-8949/1995/T59/060, Phys. Rev. A 98, 010101 (2018)PLRAAN2469-992610.1103/PhysRevA.98.010101].

Generation of field-reversed configurations via neutral beam injection

We report evidence of successful generation of field-reversed configuration plasmas by neutral beam injection. This is achieved by trapping the steady-state beams in an initial seed plasma, hence providing a direct source of toroidally directed energetic ion current and increase plasma density and temperature until plasma and magnetic pressures become comparable. Magnetic flux trapping occurs gradually, and the change in topology from open field line to fully a formed field-reversed configuration is complete within ~ 10 ms. Field reversal is first established using a traditional metric and complemented by advanced reconstruction algorithms of the magnetic topology and plasma pressure profiles; observations of characteristic changes to fast-ion orbits inferred from magnetic fluctuations; and an experimentally validated model of field reversal by neutral beam injection. These results establish a field-reversed configuration formation method which may offer technological and economic advantages on a path to a future fusion energy system.

A compact high-flux grating chip cold atom source

Abstract Diffraction gratings have simplified the optical implementation of magneto-optical traps (MOTs) to require only a single input beam, however reaching high atom number and fast loading has proven to be a challenge. We equipped an atom chip with a grating surface and paired it with a velocity-tunable 2D+-MOT as an atomic source to facilitate efficient loading together with magnetic trapping. Using uniform grating illumination, we magneto-optically trap 1.0 ( 1 ) × 10 9 atoms within one second, cool them to 14.1 ( 3 ) μ K , and transfer a quarter of them into the magnetic chip trap. This is a key step towards simple portable quantum sensors employing (ultra-)cold atoms.

Cold source of atomic hydrogen for loading large magnetic traps

We present a design and performance tests of an intense source of cold hydrogen atoms for loading large magnetic traps. Our source is based on a cryogenic dissociator of molecular hydrogen at 0.6 K followed by a series of thermal accommodators at 0.5, 0.2 and 0.13 K with inner surfaces covered by a superfluid helium film. All components are thermally anchored to corresponding stages of a dilution refrigerator. The source provides a continuous flux of 7×1013 H atoms/s in a temperature range of 130–200 mK. We have successfully used the source for loading a large Ioffe–Pritchard magnetic trap recently built in our laboratory (Ahokas et al. in Rev Sci Instrum 93(2):023201, 2022). Calorimetric measurements of the atomic recombination heat allow reliable determination of the atomic flux and H gas density in the trap. We have tested the performance of the source and loading of H atoms into the trap at various configurations of the trapping field, reducing the magnetic barrier height to 75% and 50% of the nominal value of 0.8 T (0.54 K) as well as at the open configuration of the trap at its lower end, when the atoms are in contact with the trapping cell walls covered by a superfluid helium film. In the latter case, raising the trapping cell temperature to 200–250 mK, the low-field seeking atoms at densities exceeding 1011 cm-3 can be stored for the time over 103 s, sufficiently long for experiments on precision spectroscopy of cold H gas.Graphic abstract

Cover Picture: Contrib. Plasma Phys. 03/2025

Diagram of beam distribution of the magnetic trap at 50 ns with different beam incidence velocities. Green points represent protons, red points represent electrons and blue lines represent magnetic induction lines. Part of Fig. 6 of the paper by Fang‐Ping Wang et al. https://doi.org/10.1002/ctpp.202400040 image

Magnetic Capture of Functionalized Nanoscale Zerovalent Iron for Soil Remediation: A Feasibility Study on Transport Control.

Nanoscale zerovalent iron (nZVI) has been proposed as a promising nanomaterial for soil remediation. However, injecting nZVI into contaminated sites to target and treat pollutant sources may pose potential environmental risks due to its colloidal stability and mobility in the environment. In this regard, this study assessed the feasibility of implementing magnetic capture of surface-functionalized nZVI in soil environments under the influence of the convective flow current. Here, functionalized nZVI particles were prepared by introducing carboxymethyl cellulose (CMC) as a stabilizing agent during the synthesis of nZVI by using the liquid-phase reduction method. The functionalized nZVI particles were then injected into a two-dimensional flow column containing a sand matrix with a high gradient magnetic trap (HGMT) embedded within the system. Particle transports in both the absence and presence of a magnetic field were recorded by using a digital camera, and the breakthrough curves were generated from the data collected spectrophotometrically. The results showed that the relative breakthrough concentration of nZVI decreased from 0.92 to nearly zero, with a delayed breakthrough time as the applied magnetic field strength increased from zero (no magnetic field) to 0.093 T, demonstrating a 100% capture efficiency. It was found that the magnetic capture for the nZVI particles was contributed by two mechanisms: (1) low gradient magnetic separation (LGMS), driven by the penetrating magnetic field from the permanent magnets, and (2) high gradient magnetic separation (HGMS), which occurred near the wire surfaces within the HGMT section magnetized by the permanent magnets. Findings in this work have proven the feasibility of magnetic separation as a control strategy for nanoparticle applications in environmental remediation.

Matter-wave lensing of ultracold atomic gases by interaction quenching via two-photon scattering

Precision quantum sensors using cold atom interferometers with long interrogation times are often limited by the ballistic expansion of atomic samples after release from traps, manifesting by means of laser beam wavefront uncertainties. In this study we utilize near-resonant light interacting with an ultracold atomic sample for collective-mode excitation of a 87Rb Bose Einstein condensate (BEC) in a magnetic trap. The collective motion is initiated after abruptly modifying the atom-atom interaction energy by reduction of the BEC atom number density via photon scattering using the two-photon transition from 5S1/2 to 5D5/2. We show that the two-photon transition can induce matter-wave lensing of the atomic cloud with minimal center-of-mass perturbation providing an optimal ultra-cold atomic sample for atom-based quantum sensors such as quantum gravimeters and accelerometers.

Number Count Characteristics of Cold Atoms in a Magnetic Trap for Temperature Estimation

Abstract Temperature estimation of cold atoms in sub-Doppler to Doppler temperatures is crucial for determining various aspects such as diffusion, compressibility, trap stability, phase transition, and many-body collision dynamics. In this temperature regime, cold atoms are typically confined in a magnetic trap for further investigation. In some cases, temperature estimation from a typical time-of-flight method is not applicable due to the long switch-off time of the magnetic trap. In this work, we employ a non-invasive number counting method without having to turn off the magnetic field to estimate the temperature. We explore various number count conditions for a temperature range between 20 µK to 100 µK in such a way that the trace of number counts can be used as a reference to estimate the temperature of cold atoms in a magnetic trap.

A simple Magnetic-aided microfluidic screening approach for rabies virus via rolling circle amplification

A simple Magnetic-aided microfluidic screening approach for rabies virus via rolling circle amplification

Magnetic Field-Induced Ion Trapping Around Dust Particle in Plasma

Magnetic Field-Induced Ion Trapping Around Dust Particle in Plasma

An Algorithm to Calculate the Magnetic Field in a Helical Magnetic Trap

An Algorithm to Calculate the Magnetic Field in a Helical Magnetic Trap

Rotating Magnetic Gravitational Trap for Storing Ultracold Neutrons

The paper proposes an experiment to measure the neutron lifetime by storing ultracold neutrons in a rotating magnetic trap. The magnetic trap is a set of NdFeB permanent magnets. By rotating the trap around a horizontal axis, it is possible to carry out gravitational capture of ultracold neutrons and their holding. A design option is presented when two traps are located in one installation on the same axis: material and magnetic. The sensitivity of the magnetic trap was assessed in comparison with the material one under equal measurement conditions. One of the factors influencing the systematic error of the experiment will be the process of neutron depolarization in a magnetic field. Therefore, the paper considers the issue of developing a magnetic system that minimizes the probability of neutron depolarization. The so-called turbine effect is also considered, which can manifest itself in a change in the energy of ultracold neutrons during rotation due to interaction with the flat faces of the trap. The proposed gravitational capture of ultracold neutrons in a magnetic trap is a fundamentally new approach that has never been implemented before. The experiment can be carried out on the ultracold neutron source under construction at the PIK reactor.

Ultracold neutron source based on superfluid helium for the PIK Reactor

A high density ultracold neutron source based on superfluid helium is going to be created in NRC “Kurchatov Institute” — PNPI for scientific research in fundamental physics. The ultracold neutron source is to be installed on the Horizontal Experimental Channel 4 (HEC-4), which is the biggest of available experimental channels of PIK Reactor Complex. Thermal neutron flux density at the channel outlet is expected to be around 3 ×1010 cm–2s–1. The new ultracold neutron source at the PIK Reactor is planned to achieve a density of 2.2 ×103 cm–3 at ultracold neutron neutron guide exit and 200 cm–3 at neutron electric dipole moment spectrometer facility. The designed ultracold neutron guide system is going to support five experimental facilities alternately. At the initial stage the ultracold neutron source is planned to be equipped with already existing PNPI experimental plants: a neutron electric dipole moment spectrometer and neutron lifetime measuring facilities (with a gravitational and magnetic trap). A unique technological cryogenic complex with superfluid helium was designed and realized for this ultracold neutron source. Said complex includes equipment for achieving temperatures down to 1 K and removal of up to 60 W of heat from superfluid helium.

Pulsed loading of a magneto-optical trap on an atom chip with fast recovery of ultrahigh vacuum

Abstract Here, we present studies on pulsed loading of a rubidium (Rb) magneto-optical trap (MOT) in an ultra-high vacuum (UHV) environment on an atom chip. We have used a parallel combination of Rb dispensers for better heat dissipation to achieve fast UHV recovery in the chamber after the end of the current pulse to the dispensers. We have estimated the threshold heat energy required for activation of the dispensers for different values of current pulses. Although a pulse with a higher current value and shorter duration has a lower threshold heat energy, we operated the dispensers at moderate current pulse parameters (24 A, 10 s) for protection of the circuits. Nearly, 3 × 10 7 cold 87 Rb atoms were loaded in the MOT using this current pulse, with a UHV recovery time of ∼600 ms in the chamber. This fast recovery of UHV in the MOT chamber is useful for further experiments such as magnetic trapping and evaporative cooling of atoms in the same chamber.

Magnetic trapping of an ultracold 39K-40K mixture with a versatile potassium laser system.

We present a dual isotope magneto-optical trap (MOT), simultaneous sub-Doppler laser cooling, and magnetic trapping of a spin-polarized 39K-40K Bose-Fermi mixture realized in a single-chamber setup with an unenriched potassium dispenser as the source of atoms. We are able to magnetically confine more than 2.2 × 105 fermions (F = 9/2 , m F = 9/2) and 1.4 × 107 bosons (F = 2 , m F = 2) with a lifetime exceeding 1.2 s. For this work, we have developed a versatile laser tailored for sub-Doppler cooling of all naturally occurring potassium isotopes and their mixtures. This laser system incorporates innovative features, such as the capability to select an isotope by activating or deactivating specific acousto-optic modulators that control the light seeding tapered amplifiers. Switching between isotopes takes ∼1µs without any mechanical adjustment of the components.