Prospects for quantum computing with an array of ultracold polar paramagnetic molecules

Karra, Mallikarjun; Sharma, Ketan; Friedrich, Břetislav; Kais, Sabre; Herschbach, D. R.

doi:10.1063/1.4942928

Cited by 82 publications

(70 citation statements)

References 63 publications

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“…The Deutsch algorithm provides a proofof-principle experiment to demonstrate the use of ultracold molecules to perform quantum computation. Scalability may be achieved in the future by implementing gates involving multiple molecules, confined in an array of tweezers and linked by the dipole-dipole interaction [63][64][65][66][67][68][69].…”

Section: Resultsmentioning

confidence: 99%

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Ultracold polar molecules as qudits

et al. 2020

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We discuss how the internal structure of ultracold molecules, trapped in the motional ground state of optical tweezers, can be used to implement qudits. We explore the rotational, fine and hyperfine structure of 40 Ca 19 F and 87 Rb 133 Cs, which are examples of molecules with 2 Σ and 1 Σ electronic ground states, respectively. In each case we identify a subset of levels within a single rotational manifold suitable to implement a four-level qudit. Quantum gates can be implemented using two-photon microwave transitions via levels in a neighboring rotational manifold. We discuss limitations to the usefulness of molecular qudits, arising from off-resonant excitation and decoherence. As an example, we present a protocol for using a molecular qudit of dimension d=4 to perform the Deutsch algorithm.

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Section: Resultsmentioning

confidence: 99%

“…Heteronuclear molecules can have electric dipole moments fixed in the molecular frame, allowing manipulation of the quantum states with microwave fields [57][58][59]62]. A quantum computer formed from ultracold polar molecules can be increased in scale by linking neighboring molecules via the long-range dipole-dipole interaction [63][64][65][66][67][68][69].…”

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confidence: 99%

Ultracold polar molecules as qudits

et al. 2020

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“…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%

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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“…[1][2][3][4][5][6] Amongt he many possible schemesf or realizing quantum computers, arrays of trapped ultracoldp olar molecules subject to an external electric field are considered ap romising approach. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] In such ad ipole array,e ach polar molecule acts as aq ubit entangled with the other molecules via electric dipole-dipole interaction. Using the Stark effect due to an inhomogeneouse xternale lectric field, qubits encoded in rotational states can be individually addressed and manipulated.…”

Section: Introductionmentioning

confidence: 99%

Quantum Computation using Arrays of N Polar Molecules in Pendular States

Cao

Kais

et al. 2016

ChemPhysChem

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We investigate several aspects of realizing quantum computation using entangled polar molecules in pendular states. Quantum algorithms typically start from a product state |00⋯0⟩ and we show that up to a negligible error, the ground states of polar molecule arrays can be considered as the unentangled qubit basis state |00⋯0⟩ . This state can be prepared by simply allowing the system to reach thermal equilibrium at low temperature (<1 mK). We also evaluate entanglement, characterized by concurrence of pendular state qubits in dipole arrays as governed by the external electric field, dipole-dipole coupling and number N of molecules in the array. In the parameter regime that we consider for quantum computing, we find that qubit entanglement is modest, typically no greater than 10 , confirming the negligible entanglement in the ground state. We discuss methods for realizing quantum computation in the gate model, measurement-based model, instantaneous quantum polynomial time circuits and the adiabatic model using polar molecules in pendular states.

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Prospects for quantum computing with an array of ultracold polar paramagnetic molecules

Cited by 82 publications

References 63 publications

Ultracold polar molecules as qudits

Ultracold polar molecules as qudits

A scalable quantum computing platform using symmetric-top molecules

Quantum Computation using Arrays of N Polar Molecules in Pendular States

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