arXiv subjects

Boris B. Blinov

Publications and source records attributed to Boris B. Blinov.

17 recordsLinked to original sources

arXiv2026

Barium Magnesium Alloy as Source of Atomic Ba for Ion Trapping

Trapped atomic ion qubits exhibit long coherence times and high fidelity qubit state preparation, manipulation and detection, making them well-suited for scalable quantum computing applications. Among several atomic species used in quantum computing and other application, singly-charged ions of barium stand out due to their long wavelength transitions and the presence of very long-lived metastable internal states. However, elemental barium is a highly reactive metal making it experimentally difficult to work with when making atomic beam sources. In this paper, we demonstrate a method of using resistively heated ovens loaded with a barium magnesium alloy (BaMg) as a source of barium for ion traps. This alloy is not very chemically reactive and does not oxidize in air. We found that a sample of BaMg in a resistively heated oven produced barium vapor pressures on the same order as a metallic barium sample prepared the same way. Two separate ovens, one with a sample of BaMg and one with metallic barium, were used as source for an ion trap. We observed reliable trapping of 138Ba+ ions both with the elemental barium source, and the BaMg source.

physics.atom-ph↗

arXiv2025

An Accessible Planar Charged Particle Trap for Experiential Learning in Quantum Technologies

We describe an inexpensive and accessible instructional setup that explores particle trapping with a planar linear ion trap. The planar trap is constructed using standard printed circuit board manufacturing and is designed to trap macroscopic charged particles in air. Trapping, shuttling, and splitting are demonstrated to students using these particles, which are visible to the naked eye. Students control trap voltages and can compare properties of particle motion with an analytic model of the trap using a computer vision program for particle tracking. Learning outcomes include understanding the design considerations for planar AC traps, mechanisms underpinning particle ejection, the physics of micromotion, and methods of data analysis using standard computer vision libraries.

quant-ph↗

arXiv2025

Structural Transitions and Melting of Two-Dimensional Ion Crystals in RF Traps

We investigate the structural properties and melting behavior of two-dimensional ion crystals in an RF trap, focusing on the effects of ion temperature and trap potential symmetry. We identify distinct crystal structures that form under varying trapping conditions and temperatures through experimental observations and theoretical analyses. As the temperature increases or the trap potential becomes more symmetric, we observe a transition from a lattice arrangement to elongated ring-like formations aligned along the trap axes. Our experimental and theoretical efforts enhance our understanding of phase transitions in low-dimensional, confined systems, offering insights into the controlled formation of quantum crystals for applications in quantum simulations and many-body physics.

physics.atom-ph↗

arXiv2023

Micromotion-Synchronized Pulsed Doppler Cooling of Trapped Ions

We propose and demonstrate a new method for Doppler cooling trapped-ion crystals where the distribution of micromotion amplitudes may be large and uneven. The technique uses pulses of Doppler cooling light synchronized with the trap RF that selectively target ions when their velocity is near a node, leading to more uniform cooling across a crystal by a single tone of cooling light. We lay out a theoretical framework that describes where this technique is practical, and provide a simple experimental demonstration.

physics.atom-ph↗

arXiv2022

Two-tone Doppler cooling of radial two-dimensional crystals in a radiofrequency ion trap

We study the Doppler-cooling of radial two-dimensional (2D) Coulomb crystals of trapped barium ions in a radiofrequency trap. Ions in radial 2D crystals experience micromotion of an amplitude that increases linearly with the distance from the trap center, leading to a position-dependent frequency modulation of laser light in each ion's rest frame. We use two tones of Doppler-cooling laser light separated by approximately 100~MHz to efficiently cool distinct regions in the crystals with differing amplitudes of micromotion. This technique allows us to trap and cool more than 50 ions populating 4 shells in a radial two-dimensional crystal, where with a single tone of Doppler cooling light we are limited to 30 ions in 3 shells. We also individually characterize the micromotion of all ions within the crystals, and use this information to locate the center of the trap and to determine the Matthieu parameters $q_{x}$ and $q_{y}$.

physics.atom-ph↗

arXiv2021

Efficient sympathetic cooling in mixed barium and ytterbium ion chains

We study sympathetic cooling of the radial ion motion in a linear RF trap in mixed barium-ytterbium chains. Barium ions are Doppler-cooled, while ytterbium ions are cooled through their interaction with cold barium ions. We estimate the efficiency of sympathetic cooling by measuring the average occupation quantum numbers, and thus the temperature, of all radial normal modes of motion in the ion chain. The full set of orderings in a chain of two barium and two ytterbium ions have been probed, and we show that the average thermal occupation numbers for all chain configurations strongly depend on the trap aspect ratio. We demonstrate efficient sympathetic cooling of all radial normal modes for the trap aspect ratio of approximately 2.9.

physics.atom-ph↗

arXiv2021

Direct Observation of Ion Micromotion in a Linear Paul Trap

In this paper, direct observation of micromotion for multiple ions in a laser-cooled trapped ion crystal is discussed along with a novel measurement technique for micromotion amplitude. Micromotion is directly observed using a time-resolving, single-photon sensitive camera that provides both fluorescence and position data for each ion on the nanosecond time scale. Micromotion amplitude and phase for each ion in the crystal are measured, allowing this method to be sensitive to tilts and shifts of the ion chain from the null of the radiofrequency quadrupole potential in the linear trap. Spatial resolution makes this micromotion detection technique suitable for complex ion configurations, including two-dimensional geometries. It does not require any additional equipment or laser beams, and the modulation of the cooling lasers or trap voltages is not necessary for detection, as it is in other methods.

physics.atom-ph↗

arXiv2021

High-Fidelity Simultaneous Detection of Trapped Ion Qubit Register

Qubit state detection is an important part of a quantum computation. As number of qubits in a quantum register increases, it is necessary to maintain high fidelity detection to accurately measure the multi-qubit state. Here we present experimental demonstration of high-fidelity detection of a multi-qubit trapped ion register with average single qubit detection error of 4.2(1.5) ppm and a 4-qubit state detection error of 17(2) ppm, limited by the decay lifetime of the qubit, using a novel single-photon-sensitive camera with fast data collection, excellent temporal and spatial resolution, and low instrumental crosstalk.

quant-ph↗

arXiv2021

Cold ion beam in a storage ring as a platform for large-scale quantum computers and simulators: challenges and directions for research and development

The purpose of this paper is to evaluate the possibility of constructing a large-scale storage-ring-type ion-trap system capable of storing, cooling, and controlling a large number of ions as a platform for scalable quantum computing (QC) and quantum simulations (QS). In such a trap, the ions form a crystalline beam moving along a circular path with a constant velocity determined by the frequency and intensity of the cooling lasers. In this paper we consider a large leap forward in terms of the number of qubits, from fewer than 100 available in state-of-the-art linear ion-trap devices today to an order of 105 crystallized ions in the storage-ring setup. This new trap design unifies two different concepts: the storage rings of charged particles and the linear ion traps used for QC and mass spectrometry. In this paper we use the language of particle accelerators to discuss the ion state and dynamics. We outline the differences between the above concepts, analyze challenges of the large ring with a revolving beam of ions, and propose goals for the research and development required to enable future quantum computers with 1000 times more qubits than available today. The challenge of creating such a large-scale quantum system while maintaining the necessary coherence of the qubits and the high fidelity of quantum logic operations is significant. Performing analog quantum simulations may be an achievable initial goal for such a device. Quantum simulations of complex quantum systems will move forward both the fundamental science and the applied research. Nuclear and particle physics, many-body quantum systems, lattice gauge theories, and nuclear structure calculations are just a few examples in which a large-scale quantum simulation system would be a very powerful tool to move forward our understanding of nature.

quant-ph↗

arXiv2020

Photon-mediated entanglement scheme between a ZnO semiconductor defect and a trapped Yb ion

We propose an optical scheme to generate an entangled state between a trapped ion and a solid state donor qubit through which-path erasure of identical photons emitted from the two systems. The proposed scheme leverages the similar transition frequencies between In donor bound excitons in ZnO and the $^2P_{1/2}$ to $^2S_{1/2}$ transition in Yb$^+$. The lifetime of the relevant ionic state is longer than that of the ZnO system by a factor of 6, leading to a mismatch in the temporal profiles of emitted photons. A detuned cavity-assisted Raman scheme weakly excites the donor with a shaped laser pulse to generate photons with 0.99 temporal overlap to the Yb$^+$ emission and partially shift the emission of the defect toward the Yb$^+$ transition. The remaining photon shift is accomplished via the dc Stark effect. We show that an entanglement rate of 21 kHz and entanglement fidelity of 94 % can be attained using a weak excitation scheme with reasonable parameters.

quant-ph↗

arXiv2016

An Upper Bound on the Strongly Forbidden $6S_{1/2} \leftrightarrow 5D_{3/2}$ Magnetic Dipole Transition Moment in {Ba}$^{+}$

We report the results from our first-generation experiment to measure the magnetic-dipole transition moment (M1) between the $6S_{1/2}$ and $5D_{3/2}$ manifolds in Ba$^{+}$. Knowledge of M1 is crucial for the proposed parity-nonconservation experiment in the ion \cite{Fortson93}, where M1 will be a leading source of systematic error. To date, no measurement of M1 has been made in Ba$^{+}$, and moreover, the sensitivity of the moment to electron-electron correlations has confounded accurate theoretical predictions. A precise measurement may help to resolve the theoretical discrepancies while providing essential information for planning a future PNC measurement in Ba$^{+}$. We demonstrate our technique for measuring M1 - including a method for calibrating for stress-induced birefringence introduced by the scientific apparatus - and place an upper bound of $\mathrm{M1} < 93 \pm 39 \times 10^{-5} μ_{B}$.

physics.atom-ph↗

arXiv2014

Measurement of the branching fractions and lifetime of the $5D_{5/2}$ level of Ba$^+$

We present a measurement of the branching fractions for decay from the long-lived $5D_{5/2}$ level in \Ba. The branching fraction for decay into the $6S_{1/2}$ ground state was found to be $0.846(25)_{\mathrm{stat}}(4)_{\mathrm{sys}}$. We also report an improved measurement of the $5D_{5/2}$ lifetime, $τ_{5D_{5/2}}=31.2(0.9)$~s. Together these measurements provide the first experimental determination of transition rates for decay out of the $5D_{5/2}$ level. The low ($<7 \times 10^{-12}$~Torr) pressure in the ion trap in which these measurements were made simplified data acquisition and analysis. Comparison of the experimental results with theoretical predictions of the transition rates shows good agreement.

physics.atom-ph↗

arXiv2014

Scalable Quantum Computing Architecture with Mixed Species Ion Chains

We report on progress towards implementing mixed ion species quantum information processing for a scalable ion trap architecture. Mixed species chains may help solve several problems with scaling ion trap quantum computation to large numbers of qubits. Initial temperature measurements of linear Coulomb crystals containing barium and ytterbium ions indicate that the mass difference does not significantly impede cooling at low ion numbers. Average motional occupation numbers are estimated to be $\bar{n} \approx 130$ quanta per mode for chains with small numbers of ions, which is within a factor of three of the Doppler limit for barium ions in our trap. We also discuss generation of ion-photon entanglement with barium ions with a fidelity of $F \ge 0.84$, which is an initial step towards remote ion-ion coupling in a more scalable quantum information architecture. Further, we are working to implement these techniques in surface traps in order to exercise greater control over ion chain ordering and positioning.

quant-ph↗

arXiv2013

Ion-Photon Entanglement and Bell Inequality Violation with 138Ba+

We report on the demonstration of ion-photon entanglement and Bell inequality violation in a system of trapped 138Ba+ ions. Entanglement between the Zeeman sublevels of the ground state of a single 138Ba+ ion and the polarization state of a single 493 nm photon emitted by the ion with a fidelity of $0.84\pm0.01$ was achieved, along with a Bell signal of 2.3, exceeding the classical limit of 2 by over eight standard deviations. This system is a promising candidate for a loophole-free Bell inequality violation test as the wavelengths of the transitions of 138Ba+ are in the visible region and thus suitable for long range transmission over fiber optic cable.

physics.atom-ph↗

arXiv2013

Radio frequency spectroscopy measurement of the Landé g factor of the 5D5/2 state of Ba+ with a single trapped ion

We report an improved measurement of the Landé g factor of the 5D5/2 state of singly ionized barium. Measurements were performed on single Doppler-cooled 138Ba+ ions in linear Paul traps using two similar, independent apparatuses. Transitions between Zeeman sublevels of the 6S1/2 and 5D5/2 states were driven with two independent, stabilized radio-frequency synthesizers using a dedicated electrode within each ion trap chamber. State detection within each Zeeman manifold was achieved with a frequency-stabilized fiber laser operating at 1.76 microns. By calculating the ratio of the two Zeeman splittings, and using the measured Landé g factor of the 6S1/2 state, we find a value of 1.200371(4stat)(6sys) for g of 5D5/2.

physics.atom-ph↗

arXiv2013

A Method for Measuring the $6S_{1/2} \leftrightarrow 5D_{3/2}$ Magnetic Dipole Transition Moment in {Ba}$^{+}$

We propose a method for measuring the magnetic dipole (M1) transition moment of the $6S_{1/2} \big(\mathrm{m}=-1/2\big)\leftrightarrow 5D_{3/2}\big(\mathrm{m}=-1/2\big)$ transition in single trapped Ba$^{+}$ by exploiting different symmetries in the electric quadrupole (E2) and M1 couplings between the states. The technique is adapted from a previously proposed method for measuring atomic parity nonconservation in a single trapped ion [Norval Fortson, Phys. Rev. Lett. \textbf{70}, 17 (1993)]. Knowledge of M1 is crucial for any parity nonconservation measurement in Ba$^{+}$, as laser coupling through M1 can mimic the parity-violating signal. The magnetic moment for the transition has been calculated by atomic theory and found to be dominated by electron-electron correlation effects [B.K. Sahoo et. al., Phys. Rev. A \textbf{74}, 6 (2006)]. To date the value has not been verified experimentally. This proposed measurement is therefore an essential step toward a parity nonconservation experiment in the ion that will also test current many-body theory. The technique can be adapted for similar parity nonconservation experiments using other atomic ions, where the magnetic dipole moment could present similar complications.

physics.atom-ph↗

arXiv2012

Coherent Excitation of the 6S1/2 to 5D3/2 Electric Quadrupole Transition in 138Ba+

The electric dipole-forbidden, quadrupole 6S1/2 <-> 5D3/2 transition in Ba+ near 2051 nm, with a natural linewidth of 13 mHz, is attractive for potential observation of parity non-conservation, and also as a clock transition for a barium ion optical frequency standard. This transition also offers a direct means of populating the metastable 5D3/2 state to measure the nuclear magnetic octupole moment in the odd barium isotopes. Light from a diode-pumped, solid state Tm,Ho:YLF laser operating at 2051 nm is used to coherently drive this transition between resolved Zeeman levels in a single trapped 138Ba+ ion. The frequency of the laser is stabilized to a high finesse Fabry Perot cavity at 1025 nm after being frequency doubled. Rabi oscillations on this transition indicate a laser-ion coherence time of 3 ms, most likely limited by ambient magnetic field fluctuations.

physics.atom-ph↗