Accurate microwave control and real-time diagnostics of neutral-atom qubits

Rakreungdet, Worawarong; Lee, Jae Hoon; Lee, Kim Fook; Mischuck, Brian; Montaño, Enrique; Jessen, Poul

doi:10.1103/physreva.79.022316

Cited by 41 publications

(36 citation statements)

References 30 publications

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“…In the second experiment, we considered a composite pulse to achieve a higher-fidelity Rabi oscillation. We tested the three-pulse composite consisting of two π/2 rotations about x-axis and a π rotation about y-axis, or R x (π/2)R y (π)R x (π/2), which sequence of pulses is well-known in NMR designed to correct errors caused by pulsearea fluctuation [31,32]. The π-rotation R y (π) about the y-axis in the middle corrects the rotation error of the pair of π/2 rotations R x (π/2) 2 .…”

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confidence: 99%

Ultrafast laser-driven Rabi oscillations of a trapped atomic vapor

2015

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We investigate Rabi oscillation of an atom ensemble in Gaussian spatial distribution. By using the ultrafast laser interaction with the cold atomic rubidium vapor spatially confined in a magnetooptical trap, the oscillatory behavior of the atom excitation is probed as a function of the laser pulse power. Theoretical model calculation predicts that the oscillation peaks of the ensemble-atom Rabi flopping fall on the simple Rabi oscillation curve of a single atom and the experimental result shows good agreement with the prediction. We also test the the three-pulse composite interaction Rx(π/2)Ry(π)Rx(π/2) to develop a robust method to achieve a higher fidelity population inversion of the atom ensemble.PACS numbers: 32.80. Qk, 32.80.Wr, 42.65.Re Rabi oscillation is a fundamental concept in physics with a significant pedigree first discovered in the context of nuclear magnetic resonance (NMR) [1][2][3] and later extended to atomic physics and quantum optics [4,5]. In the presence of an oscillatory driving field E(t) = A(t) cos(ωt), a two-state quantum system undergoes a cyclic change of Bloch vector ρ manifested by the precessionabout an effective torque Ω = (−µA(t)/2 , 0, δ), where µ is the transition dipole moment between the two energy states, A(t) is the field envelope, and δ is the frequency detuning under the slowly-varying envelope approximation [4]. This generic feature of Rabi oscillation is universally found in a vast variety of material systems ranging from simple atoms and molecules [6][7][8][9][10] When a two-state atom interacts with a resonant (δ = 0) laser pulse, the dynamics of the excited state probability, which we may refer to as single-atom Rabi oscillation (SARO), is represented bywhere Θ o is the pulse area defined by Θ o = µA(t)dt/ . Since the pulse area is subject to both the pulse duration and the electric-field envelope, Rabi oscillations of an ultra-short time scale can be implemented by ultrafast optical interaction at a strong-enough laser intensity regime. However, the spatial extent of the laser beam over the laser-atom interaction region inevitably causes spatial average effect that often leads to vanishing of the oscillatory behavior. To overcome this problem, homogenizing the spatial profile of laser beams [22,23] and * Electronic address: jwahn@kaist.ac.kr adapting chirped laser interaction [24] have been considered. This paper aims quantitative analysis of spatially averaged Rabi oscillation. For this, we use the atom ensemble localized in a magneto-optical trap (MOT) [25] interacted with ultrafast laser pulses. As a theoretical model to investigate the spatially inhomogeneous interaction, we consider a Gaussian laser beam propagating along z direction. The pulse area in Eq. (2) is then represented in the polar coordinate system aswhere r = x 2 + y 2 , w(z) is the beam waist at z, w o = w(0) is the minimal beam waist, Θ o is the maximal pulse area, and Θ z = w o Θ o /w(z). When we assume the atom density profile in the MOT is also a Gaussian, i.e., ρ(r, z) = ρ o e −(r 2 +z 2 ...

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confidence: 99%

Ultrafast laser-driven Rabi oscillations of a trapped atomic vapor

2015

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“…After the rotating-wave approximation, the atom-field interaction is described by the two-level Hamiltonian8:…”

Section: Resultsmentioning

confidence: 99%

Inductively guided circuits for ultracold dressed atoms

et al. 2014

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Recent progress in optics, atomic physics and material science has paved the way to study quantum effects in ultracold atomic alkali gases confined to non-trivial geometries. Multiply connected traps for cold atoms can be prepared by combining inhomogeneous distributions of DC and radio-frequency electromagnetic fields with optical fields that require complex systems for frequency control and stabilization. Here we propose a flexible and robust scheme that creates closed quasi-one-dimensional guides for ultracold atoms through the ‘dressing’ of hyperfine sublevels of the atomic ground state, where the dressing field is spatially modulated by inductive effects over a micro-engineered conducting loop. Remarkably, for commonly used atomic species (for example, 7Li and 87Rb), the guide operation relies entirely on controlling static and low-frequency fields in the regimes of radio-frequency and microwave frequencies. This novel trapping scheme can be implemented with current technology for micro-fabrication and electronic control.

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“…A basic means of reducing dephasing in Rabi flopping is the rotary echo [23,45], which may be considered the simplest composite rotation. Reminiscent of Hahn's spin echo [28], this is a repeated application of the sequence θ φ θ φ+180 ; when θ = 360 • , as illustrated in Figure 3d, the 180 • phase shift every whole Rabi cycle causes a periodic reflection of state vector trajectories and realignment, or Figure 8, and is from simulations for typical parameters given in Table II.…”

Section: B Rotary Echoesmentioning

confidence: 99%

“…The various pulse sequences differ in their tolerance of 'pulse length' (or coupling strength) and 'off-resonance' errors and correlations between them, and in the operations for which they are suitable and the properties whose fidelity they protect. All are in principle applicable to the coherent control of any other two-state superposition, and such techniques have been applied to the manipulation of superconducting qubits [15], diamond NV colour-centres [16], trapped ions [3,[17][18][19][20][21], microwave control of neutral atoms [22][23][24][25][26], and even the polarization of light [27].…”

Section: Introductionmentioning

confidence: 99%

Composite pulses for interferometry in a thermal cold atom cloud

et al. 2014

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Atom interferometric sensors and quantum information processors must maintain coherence while the evolving quantum wavefunction is split, transformed and recombined, but suffer from experimental inhomogeneities and uncertainties in the speeds and paths of these operations. Several error-correction techniques have been proposed to isolate the variable of interest. Here we apply composite pulse methods to velocity-sensitive Raman state manipulation in a freely-expanding thermal atom cloud. We compare several established pulse sequences, and follow the state evolution within them. The agreement between measurements and simple predictions shows the underlying coherence of the atom ensemble, and the inversion infidelity in an 80 micro-Kelvin atom cloud is halved. Composite pulse techniques, especially if tailored for atom interferometric applications, should allow greater interferometer areas, larger atomic samples and longer interaction times, and hence improve the sensitivity of quantum technologies from inertial sensing and clocks to quantum information processors and tests of fundamental physics

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Accurate microwave control and real-time diagnostics of neutral-atom qubits

Cited by 41 publications

References 30 publications

Ultrafast laser-driven Rabi oscillations of a trapped atomic vapor

Ultrafast laser-driven Rabi oscillations of a trapped atomic vapor

Inductively guided circuits for ultracold dressed atoms

Composite pulses for interferometry in a thermal cold atom cloud

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