Effect of defects on phonons and the effective spin-spin interactions of an ultracold Penning-trap quantum simulator

McAneny, M.; Yoshimura, Bryce; Freericks, J. K.

doi:10.1103/physreva.88.043434

Cited by 7 publications

(6 citation statements)

References 20 publications

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“…We compute the equilibrium positions and axial normal modes of the ion crystal in the presence of these impurities using the methods of Ref. [91]; results for a crystal of 37 Be + ions and 44 BeH + impurities are shown in Fig. 12.…”

Section: Application: Trapped Ion Spin-boson Simulators In the Prementioning

confidence: 99%

Simulating generic spin-boson models with matrix product states

2016

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The global coupling of few-level quantum systems ("spins") to a discrete set of bosonic modes is a key ingredient for many applications in quantum science, including large-scale entanglement generation, quantum simulation of the dynamics of long-range interacting spin models, and hybrid platforms for force and spin sensing. We present a general numerical framework for treating the out-of-equilibrium dynamics of such models based on matrix product states. Our approach applies for generic spin-boson systems: it treats any spatial and operator dependence of the two-body spin-boson coupling and places no restrictions on relative energy scales. We show that the full counting statistics of collective spin measurements and infidelity of quantum simulation due to spin-boson entanglement, both of which are difficult to obtain by other techniques, are readily calculable in our approach. We benchmark our method using a recently developed exact solution for a particular spin-boson coupling relevant to trapped ion quantum simulators. Finally, we show how decoherence can be incorporated within our framework using the method of quantum trajectories, and study the dynamics of an open-system spin-boson model with spatially non-uniform spin-boson coupling relevant for trapped atomic ion crystals in the presence of molecular ion impurities.Comment: 13 pages+refs. 13 figure

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Section: Application: Trapped Ion Spin-boson Simulators In the Prementioning

confidence: 99%

Simulating generic spin-boson models with matrix product states

2016

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“…reactive) collisions where exothermic chemical reactions with background gas molecules can generate, in both Penning and rf traps, co-trapped molecular ions over a wide range of trapping conditions and crystal geometries [6][7][8][9]. These contaminants alter ion-crystal eigenfrequencies and can complicate quantum logic interactions [10]. Impurities may be resonantly ejected from both radiofrequency and Penning traps, but this technique is least efficient when the impurities are similar in mass to the qubit ion [11].…”

mentioning

confidence: 99%

Reversing hydride-ion formation in quantum-information experiments withBe+

et al. 2015

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We demonstrate photodissociation of BeH + ions within a Coulomb crystal of thousands of 9 Be + ions confined in a Penning trap. Because BeH + ions are created via exothermic reactions between trapped, laser-cooled Be + ( 2 P 3/2 ) and background H2 within the vacuum chamber, they represent a major contaminant species responsible for infidelities in large-scale trapped-ion quantum information experiments. The rotational-state-insensitive dissociation scheme described here makes use of 157 nm photons to produce Be + and H as products, thereby restoring Be + ions without the need for reloading. This technique facilitates longer experiment runtimes at a given background H2 pressure, and may be adapted for removal of MgH + and AlH + impurities.PACS numbers: 52.27. Jt, 33.80.Gj, 34.50.Lf, Crystals of laser-cooled atomic ions form the basis of many experimental realizations of quantum logic gates [1][2][3] and simulations of quantum many-body physics [4][5][6]. In room-temperature vacuum systems, collisions with neutral background gas molecules limit quantum coherences and quantum logic operations [7]. Here we focus on inelastic (i.e. reactive) collisions where exothermic chemical reactions with background gas molecules can generate, in both Penning and rf traps, co-trapped molecular ions over a wide range of trapping conditions and crystal geometries [6][7][8][9]. These contaminants alter ion-crystal eigenfrequencies and can complicate quantum logic interactions [10]. Impurities may be resonantly ejected from both radiofrequency and Penning traps, but this technique is least efficient when the impurities are similar in mass to the qubit ion [11]. The rate of impurity ion formation increases linearly with the number of ion qubits in the register, and the time required for loading new ions and recalibrating the register increases with the size of the system. Therefore, experimental techniques to prevent or reverse qubit-ion chemistry will be a key tool for many-ion quantum information platforms. [18]. Given the difficulty of detecting scattered photons from dilute molecular-ion samples, rotational-state-selective PD has emerged as a critical tool for molecular ion spectroscopy [15,19] and precision measurements [16,20], while rotationally-insensitive dissociation schemes provide valuable tests of molecular * Electronic address: brian.sawyer@boulder.nist.gov ) after 9000 pulses of 157 nm photodissociation light at 1.6 mJ/pulse. We measure an increase in the Be + fraction from 81% to 97% of the constant total ion number in the crystal. Each image is 1.2 mm × 1.2 mm.

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“…In actual experiments, the ionic crystal often acquires an increasing number of impurities as a function of time, such as BeH + that form due to collisions of the beryllium ions with hydrogen molecules that are in the dilute background gas. While a theoretical treatment that includes the effect of these impurities is possible [8], we consider only the clean limit here, where there are no impurities. This simplifies the analysis below.…”

Section: Theoretical Formulationmentioning

confidence: 99%

Theoretical basis for quantum simulation with a planar ionic crystal in a Penning trap using a triangular rotating wall

2015

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One of the challenges with quantum simulation in ion traps is that the effective spin-spin exchange couplings are not uniform across the lattice. This can be particularly important in Penning trap realizations where the presence of an ellipsoidal boundary at the edge of the trap leads to dislocations in the crystal. By adding an additional anharmonic potential to better control interion spacing, and a triangular shaped rotating wall potential to reduce the appearance of dislocations, one can achieve better uniformity of the ionic positions. In this work, we calculate the axial phonon frequencies and the spin-spin interactions driven by a spin-dependent optical dipole force, and discuss what effects the more uniform ion spacing has on the spin simulation properties of Penning trap quantum simulators. Indeed, we find the spin-spin interactions behave more like a power law for a wide range of parameters.

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Effect of defects on phonons and the effective spin-spin interactions of an ultracold Penning-trap quantum simulator

Cited by 7 publications

References 20 publications

Simulating generic spin-boson models with matrix product states

Simulating generic spin-boson models with matrix product states

Reversing hydride-ion formation in quantum-information experiments withBe+

Theoretical basis for quantum simulation with a planar ionic crystal in a Penning trap using a triangular rotating wall

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