Dipolar quantum logic for freely rotating trapped molecular ions

Hudson, Eric R.; Campbell, W. C.

doi:10.1103/physreva.98.040302

Cited by 75 publications

(53 citation statements)

References 50 publications

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“…To implement 2-qubit gates in molecules, various schemes have been proposed [16,21,22,46]. Here we propose to create a 2-qubit CNOT gate by relying on the dipolar blockade [47], which has been demonstrated using neutral Rydberg atoms [48].…”

Section: Single Qubit Gates and 2-qubit Cnot Gatementioning

confidence: 99%

“…Many approaches to quantum computation have been explored in the last two decades, including trapped ions and neutral atoms [6][7][8][9], cavity QED and nonlinear optics [10][11][12], as well as superconducting circuits [13] and spin-based systems [14,15]. Approaches using ultracold polar molecules, in particular, have gained traction in recent years as a potential platform for QC [16][17][18][19][20][21][22]. Ultracold molecules could offer the coherence times of neutral atoms [23], and in addition, strong controllable long-range interactions [16,17,19].…”

Section: Introductionmentioning

confidence: 99%

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A scalable quantum computing platform using symmetric-top molecules

et al. 2019

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We propose a new scalable platform for quantum computing (QC)-an array of optically trapped symmetric-top molecules (STMs) of the alkaline earth monomethoxide (MOCH 3 ) family. Individual STMs form qubits, and the system is readily scalable to 100-1000 qubits. STM qubits have desirable features for QC compared to atoms and diatomic molecules. The additional rotational degree of freedom about the symmetric-top axis gives rise to closely spaced opposite parity K-doublets that allow full alignment at low electric fields, and the hyperfine structure naturally provides magnetically insensitive states with switchable electric dipole moments. These features lead to much reduced requirements for electric field control, provide minimal sensitivity to environmental perturbations, and allow for 2-qubit interactions that can be switched on at will. We examine in detail the internal structure of STMs relevant to our proposed platform, taking into account the full effective molecular Hamiltonian including hyperfine interactions, and identify useable STM qubit states. We then examine the effects of the electric dipolar interaction in STMs, which not only guide the design of high-fidelity gates, but also elucidate the nature of dipolar exchange in STMs. Under realistic experimental parameters, we estimate that the proposed QC platform could yield gate errors at the 10 −3 level, approaching that required for fault-tolerant QC.

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Section: Single Qubit Gates and 2-qubit Cnot Gatementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A scalable quantum computing platform using symmetric-top molecules

et al. 2019

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“…Magnetic micro-traps [41] are compatible with electronic spin doublet or triplet molecules such as CaF, SrF, YbF, or YO. Radio-frequency electric traps are compatible with molecular ions [20,32]. Such trapping potentials are sub-stantially less dependent on the rotational state of the molecule since they couple to magnetic dipoles and electric monopoles, respectively.…”

Section: A Molecular Rotorsmentioning

confidence: 99%

“…12.3]. Symmetry-adapted bases Such bases are used to block-diagonalize H-symmetric Hamiltonians acting on a space X into blocks corresponding to irreps λ ∈ H. For the {U 1 , Z 3 } example, a Z 3 -symmetric Hamiltonian written in the basis (20) will not have any matrix elements connecting different values of λ. This diagonalization procedure is ubiquitous in physics and chemistry [168,] (see also [116]).…”

Section: (C20)mentioning

confidence: 99%

Encoding a qubit in a molecule

Albert

Covey

Preskill

2019

Rochester Conference on Coherence and Quantum Optics (CQO-11)

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We construct quantum error-correcting codes that embed a finite-dimensional code space in the infinite-dimensional Hilbert state space of rotational states of a rigid body. These codes, which protect against both drift in the body's orientation and small changes in its angular momentum, may be well suited for robust storage and coherent processing of quantum information using rotational states of a polyatomic molecule. Extensions of such codes to rigid bodies with a symmetry axis are compatible with rotational states of diatomic molecules, as well as nuclear states of molecules and atoms. We also describe codes associated with general nonabelian compact Lie groups and develop orthogonality relations for coset spaces, laying the groundwork for quantum information processing with exotic configuration spaces.

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“…Trapped molecular ions have developed into indispensable tools with applications spanning cold quantum chemistry 1 , 2 , quantum computing 3 , metrology 4 and the search for new physics beyond the Standard Model 5 . In recent years, ion-neutral reactions have been studied with rovibrational quantum-state control 6 – 9 .…”

Section: Introductionmentioning

confidence: 99%

The effect of the electric trapping field on state-selective loading of molecules into rf ion traps

Keller

2020

Sci Rep

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Trapped molecular ions in pure rovibronic states are desirable in experiments ranging from cold chemistry to searches for physics beyond the Standard Model. Resonance-enhanced multiphoton ionisation (REMPI) can be used to prepare molecular ions in specific internal states with high fidelities. However, in the presence of electric fields, ionisation spectra exhibit frequency shifts and the ionisation thresholds are broadened. For this reason, REMPI studies are normally conducted in low and highly homogeneous electric fields, whereas the operating principle of rf ion traps requires electric fields that vary in space and time. In order to investigate the impact of this on the state-selectivity of REMPI in ion traps, we have simulated the expected broadening of the ionisation threshold under various operating conditions of a typical linear Paul trap. In many cases, the width of the ionisation threshold exceeds the separation between rotational energy levels, preventing state-selective ionisation. Careful choice of the trapping and laser parameters during loading can reduce this broadening, enabling state-selective ionisation in some instances. Where this strategy is not sufficient, the broadening can be reduced further by rapidly switching the trapping voltages off and on again during loading. This has been demonstrated experimentally for a Coulomb crystal of $$^{40}\hbox {Ca}^+$$ 40 Ca + ions without descrystallising it.

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Dipolar quantum logic for freely rotating trapped molecular ions

Cited by 75 publications

References 50 publications

A scalable quantum computing platform using symmetric-top molecules

A scalable quantum computing platform using symmetric-top molecules

Encoding a qubit in a molecule

The effect of the electric trapping field on state-selective loading of molecules into rf ion traps

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