Spin Quantum Computing with Endohedral Fullerenes

Harneit, Wolfgang

doi:10.1007/978-3-319-47049-8_14

Cited by 20 publications

(17 citation statements)

References 119 publications

(216 reference statements)

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“…Moreover, the increased coherence time T M = 60 μs (190 K) found for deuterated species in this study allows for high fidelity quantum gate operations to be performed as the corresponding single qubit figure of merit Q M ≈ 8000 (assuming a π pulse length of 8 ns) is quite close to the value 10 4 required for fault-tolerant quantum computation . These properties, combined with the advantage of molecular spins in addressing scalability issues through chemistry-based bottom-up approaches, show that H@Q 8 M 8 is a promising qubit candidate, equally important as endohedral fullerenes and worthy of further exploration.…”

Section: Discussionmentioning

confidence: 57%

“…These include development of new protocols and architectures to overcome scalability issues as well as tailoring of physical systems to meet the necessary requirements for being used as quantum bits (qubits) . Electron spins are natural quantum objects with relatively long coherence times that can be combined with multiple quantum degrees of freedom. , In this context, paramagnetic endohedral fullerenes (e.g., N@C 60 or P@C 60 with electron spin S = 3/2) have received increased attention because they combine the benefits of molecular materials and isolated spins: they can be precisely assembled into large arrays by chemical engineering and, under proper magnetic dilution and evasion of magnetic nuclei, exhibit long electron spin coherence times of about 200 μs both in the solid state and in solution. − …”

Section: Introductionmentioning

confidence: 99%

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Electron Spin Relaxation Mechanisms of Atomic Hydrogen Trapped in Silsesquioxane Cages: The Role of Isotope Substitution

Mitrikas

Carmieli

2021

J. Phys. Chem. C

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Encapsulated atomic hydrogen in silsesquioxane cages is a promising candidate for applications in emerging technologies like spin-based quantum computing, magnetic field sensing, and atomic clock devices. Previous studies on different polyhedral octasilsesquioxanes (POSS) of the type Si8O12R8 have shown that key parameters for quantum computing like electron spin relaxation times T 1 and T M depend strongly on the type of peripheral organic substituents. Herein we examine for the first time the effect of deuterium isotopic substitution on the spin relaxation properties of H@h 72Q8M8, the derivative with R = OSi(CH3)3, by applying pulsed electron paramagnetic resonance (EPR) methods on its deuterated analogues H@d 72Q8M8 and D@d 72Q8M8. For the latter species we measure a phase memory time of 60 μs at 190 K, the largest obtained so far for this family of molecular spins. We show that substitution of peripheral hydrogen atoms with deuterium reveals high-temperature relaxation mechanisms that were previously hidden by proton nuclear spin diffusion. Unusually short T M values observed for all deuterated species even at liquid helium temperatures are discussed in terms of tunneling reorientation of methyl groups.

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Section: Discussionmentioning

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Electron Spin Relaxation Mechanisms of Atomic Hydrogen Trapped in Silsesquioxane Cages: The Role of Isotope Substitution

Mitrikas

Carmieli

2021

J. Phys. Chem. C

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“…Considering that the spin will be ultimately exposed to the external environment, an encapsulation strategy can be highly beneficial as a protection tool from decoherence sources. This approach has been extensively employed in group V elements endohedral fullerenes, mainly 14 N@C 60 and 31 P@C 60 , with T m of the electronic spin S = 3/2 of the orders of few ms at liquid helium temperatures, and of 250 μs at 170 K. Also these record values have been observed by dilution in the almost nuclear-spin free solvent CS 2 . Similarly, S = 1/2 metallofullerenes of formula M@C 82 , with M = Sc, Y, and La, have shown T m values around 200 μs in the same temperature range .…”

Section: Long Coherence Timesmentioning

confidence: 99%

The Second Quantum Revolution: Role and Challenges of Molecular Chemistry

2019

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Implementation of modern Quantum Technologies might benefit from the remarkable quantum properties shown by molecular spin systems. In this Perspective, we highlight the role that molecular chemistry can have in the current second quantum revolution, i.e., the use of quantum physics principles to create new quantum technologies, in this specific case by means of molecular components. Herein, we briefly review the current status of the field by identifying the key advances recently made by the molecular chemistry community, such as for example the design of molecular spin qubits with long spin coherence and the realization of multiqubit architectures for quantum gates implementation. With a critical eye to the current state-of-the-art, we also highlight the main challenges needed for the further advancement of the field toward quantum technologies development.

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“…In practice three physical systems implement spin qubits: nitrogen-vacancy centres in diamond (NVC), [9] atomic impurities in semiconductors, such as P implanted in Si, [10] and paramagnetic molecules. [11][12][13] In contrast to solid-state spin qubits based on dopant atoms, such as the NVCs, molecules show a significant advantage, namely the chemical systems hosting the spin can be tailored to tune the quantum properties and the coupling to other qubits. This can create quantum platforms, [8,14,15] providing a bottomup route to large-scale quantum register fabrication.…”

Section: Introductionmentioning

confidence: 99%

First-Principles Investigation of Spin–Phonon Coupling in Vanadium-Based Molecular Spin Quantum Bits

Albino¹,

Benci²,

Tesi³

et al. 2019

Inorg. Chem.

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Paramagnetic molecules can show long spin-coherence times, which make them good candidates as quantum bits. Reducing the efficiency of the spin-phonon interaction is the primary challenge towards achieving long coherence times over a wide temperature range in soft molecular lattices. The lack of a microscopic understanding about the role of vibrations in spin relaxation strongly undermines the possibility to chemically design better performing molecular qubits. Here we report a first-principles characterization of the main mechanism contributing to the spin-phonon coupling for a class of vanadium(IV) molecular qubits. Post Hartree Fock and Density Functional Theory are used to determine the effect of both reticular and intra-molecular vibrations on the modulation of the Zeeman energy for four molecules showing different coordination geometries and ligands. This comparative study provides the first insight into the role played by coordination geometry and ligand field strength in determining the spinlattice relaxation time of molecular qubits, opening the avenue to a rational design of new compounds.

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Spin Quantum Computing with Endohedral Fullerenes

Cited by 20 publications

References 119 publications

Electron Spin Relaxation Mechanisms of Atomic Hydrogen Trapped in Silsesquioxane Cages: The Role of Isotope Substitution

Electron Spin Relaxation Mechanisms of Atomic Hydrogen Trapped in Silsesquioxane Cages: The Role of Isotope Substitution

The Second Quantum Revolution: Role and Challenges of Molecular Chemistry

First-Principles Investigation of Spin–Phonon Coupling in Vanadium-Based Molecular Spin Quantum Bits

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