Long Coherence Times in Nuclear Spin-Free Vanadyl Qubits

Chung Jui Yu; Michael J. Graham; Joseph M. Zadrozny; Jens Niklas; Matthew D. Krzyaniak; Michael R. Wasielewski; Oleg G. Poluektov; Danna E. Freedman

doi:10.1021/jacs.6b08467

Long Coherence Times in Nuclear Spin-Free Vanadyl Qubits

Chung Jui Yu, Michael J. Graham, Joseph M. Zadrozny, Jens Niklas, Matthew D. Krzyaniak, Michael R. Wasielewski, Oleg G. Poluektov, Danna E. Freedman^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

101 Scopus citations

Abstract

Quantum information processing (QIP) offers the potential to create new frontiers in fields ranging from quantum biology to cryptography. Two key figures of merit for electronic spin qubits, the smallest units of QIP, are the coherence time (T₂), the lifetime of the qubit, and the spin-lattice relaxation time (T₁), the thermally defined upper limit of T₂. To achieve QIP, processable qubits with long coherence times are required. Recent studies on (Ph₄P-d₂₀)₂[V(C₈S₈)₃], a vanadium-based qubit, demonstrate that millisecond T₂ times are achievable in transition metal complexes with nuclear spin-free environments. Applying these principles to vanadyl complexes offers a route to combine the previously established surface compatibility of the flatter vanadyl structures with a long T₂. Toward those ends, we investigated a series of four qubits, (Ph₄P)₂[VO(C₈S₈)₂] (1), (Ph₄P)₂[VO(β-C₃S₅)₂] (2), (Ph₄P)₂[VO(α-C₃S₅)₂] (3), and (Ph₄P)₂[VO(C₃S₄O)₂] (4), by pulsed electron paramagnetic resonance (EPR) spectroscopy and compared the performance of these species with our recently reported set of vanadium tris(dithiolene) complexes. Crucially we demonstrate that solutions of 1-4 in SO₂, a uniquely polar nuclear spin-free solvent, reveal T₂ values of up to 152(6) μs, comparable to the best molecular qubit candidates. Upon transitioning to vanadyl species from the tris(dithiolene) analogues, we observe a remarkable order of magnitude increase in T₁, attributed to stronger solute-solvent interactions with the polar vanadium-oxo moiety. Simultaneously, we detect a small decrease in T₂ for the vanadyl analogues relative to the tris(dithiolene) complexes. We attribute this decrease to the absence of one nuclear spin-free ligand, which served to shield the vanadium centers against solvent nuclear spins. Our results highlight new design principles for long T₁ and T₂ times by demonstrating the efficacy of ligand-based tuning of solute-solvent interactions.

Original language	English (US)
Pages (from-to)	14678-14685
Number of pages	8
Journal	Journal of the American Chemical Society
Volume	138
Issue number	44
DOIs	https://doi.org/10.1021/jacs.6b08467
State	Published - Nov 9 2016

ASJC Scopus subject areas

Catalysis
Chemistry(all)
Biochemistry
Colloid and Surface Chemistry

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10.1021/jacs.6b08467

Cite this

@article{72ff156827274a9b9bcffa661072da62,

title = "Long Coherence Times in Nuclear Spin-Free Vanadyl Qubits",

abstract = "Quantum information processing (QIP) offers the potential to create new frontiers in fields ranging from quantum biology to cryptography. Two key figures of merit for electronic spin qubits, the smallest units of QIP, are the coherence time (T2), the lifetime of the qubit, and the spin-lattice relaxation time (T1), the thermally defined upper limit of T2. To achieve QIP, processable qubits with long coherence times are required. Recent studies on (Ph4P-d20)2[V(C8S8)3], a vanadium-based qubit, demonstrate that millisecond T2 times are achievable in transition metal complexes with nuclear spin-free environments. Applying these principles to vanadyl complexes offers a route to combine the previously established surface compatibility of the flatter vanadyl structures with a long T2. Toward those ends, we investigated a series of four qubits, (Ph4P)2[VO(C8S8)2] (1), (Ph4P)2[VO(β-C3S5)2] (2), (Ph4P)2[VO(α-C3S5)2] (3), and (Ph4P)2[VO(C3S4O)2] (4), by pulsed electron paramagnetic resonance (EPR) spectroscopy and compared the performance of these species with our recently reported set of vanadium tris(dithiolene) complexes. Crucially we demonstrate that solutions of 1-4 in SO2, a uniquely polar nuclear spin-free solvent, reveal T2 values of up to 152(6) μs, comparable to the best molecular qubit candidates. Upon transitioning to vanadyl species from the tris(dithiolene) analogues, we observe a remarkable order of magnitude increase in T1, attributed to stronger solute-solvent interactions with the polar vanadium-oxo moiety. Simultaneously, we detect a small decrease in T2 for the vanadyl analogues relative to the tris(dithiolene) complexes. We attribute this decrease to the absence of one nuclear spin-free ligand, which served to shield the vanadium centers against solvent nuclear spins. Our results highlight new design principles for long T1 and T2 times by demonstrating the efficacy of ligand-based tuning of solute-solvent interactions.",

author = "Yu, {Chung Jui} and Graham, {Michael J.} and Zadrozny, {Joseph M.} and Jens Niklas and Krzyaniak, {Matthew D.} and Wasielewski, {Michael R.} and Poluektov, {Oleg G.} and Freedman, {Danna E.}",

note = "Funding Information: We acknowledge support from Northwestern University, the State of Illinois, and the National Science Foundation for CAREER Award No. CHE-1455017 (C.-J.Y., M.J.G., J.M.Z., and D.E.F.) and Award No. CHE-1565925 (M.R.W.). M.J.G. acknowledges an NSF GRFP fellowship (DGE-1324585). Publisher Copyright: {\textcopyright} 2016 American Chemical Society.",

year = "2016",

month = nov,

day = "9",

doi = "10.1021/jacs.6b08467",

language = "English (US)",

volume = "138",

pages = "14678--14685",

journal = "Journal of the American Chemical Society",

issn = "0002-7863",

publisher = "American Chemical Society",

number = "44",

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TY - JOUR

T1 - Long Coherence Times in Nuclear Spin-Free Vanadyl Qubits

AU - Yu, Chung Jui

AU - Graham, Michael J.

AU - Zadrozny, Joseph M.

AU - Niklas, Jens

AU - Krzyaniak, Matthew D.

AU - Wasielewski, Michael R.

AU - Poluektov, Oleg G.

AU - Freedman, Danna E.

N1 - Funding Information: We acknowledge support from Northwestern University, the State of Illinois, and the National Science Foundation for CAREER Award No. CHE-1455017 (C.-J.Y., M.J.G., J.M.Z., and D.E.F.) and Award No. CHE-1565925 (M.R.W.). M.J.G. acknowledges an NSF GRFP fellowship (DGE-1324585). Publisher Copyright: © 2016 American Chemical Society.

PY - 2016/11/9

Y1 - 2016/11/9

N2 - Quantum information processing (QIP) offers the potential to create new frontiers in fields ranging from quantum biology to cryptography. Two key figures of merit for electronic spin qubits, the smallest units of QIP, are the coherence time (T2), the lifetime of the qubit, and the spin-lattice relaxation time (T1), the thermally defined upper limit of T2. To achieve QIP, processable qubits with long coherence times are required. Recent studies on (Ph4P-d20)2[V(C8S8)3], a vanadium-based qubit, demonstrate that millisecond T2 times are achievable in transition metal complexes with nuclear spin-free environments. Applying these principles to vanadyl complexes offers a route to combine the previously established surface compatibility of the flatter vanadyl structures with a long T2. Toward those ends, we investigated a series of four qubits, (Ph4P)2[VO(C8S8)2] (1), (Ph4P)2[VO(β-C3S5)2] (2), (Ph4P)2[VO(α-C3S5)2] (3), and (Ph4P)2[VO(C3S4O)2] (4), by pulsed electron paramagnetic resonance (EPR) spectroscopy and compared the performance of these species with our recently reported set of vanadium tris(dithiolene) complexes. Crucially we demonstrate that solutions of 1-4 in SO2, a uniquely polar nuclear spin-free solvent, reveal T2 values of up to 152(6) μs, comparable to the best molecular qubit candidates. Upon transitioning to vanadyl species from the tris(dithiolene) analogues, we observe a remarkable order of magnitude increase in T1, attributed to stronger solute-solvent interactions with the polar vanadium-oxo moiety. Simultaneously, we detect a small decrease in T2 for the vanadyl analogues relative to the tris(dithiolene) complexes. We attribute this decrease to the absence of one nuclear spin-free ligand, which served to shield the vanadium centers against solvent nuclear spins. Our results highlight new design principles for long T1 and T2 times by demonstrating the efficacy of ligand-based tuning of solute-solvent interactions.

AB - Quantum information processing (QIP) offers the potential to create new frontiers in fields ranging from quantum biology to cryptography. Two key figures of merit for electronic spin qubits, the smallest units of QIP, are the coherence time (T2), the lifetime of the qubit, and the spin-lattice relaxation time (T1), the thermally defined upper limit of T2. To achieve QIP, processable qubits with long coherence times are required. Recent studies on (Ph4P-d20)2[V(C8S8)3], a vanadium-based qubit, demonstrate that millisecond T2 times are achievable in transition metal complexes with nuclear spin-free environments. Applying these principles to vanadyl complexes offers a route to combine the previously established surface compatibility of the flatter vanadyl structures with a long T2. Toward those ends, we investigated a series of four qubits, (Ph4P)2[VO(C8S8)2] (1), (Ph4P)2[VO(β-C3S5)2] (2), (Ph4P)2[VO(α-C3S5)2] (3), and (Ph4P)2[VO(C3S4O)2] (4), by pulsed electron paramagnetic resonance (EPR) spectroscopy and compared the performance of these species with our recently reported set of vanadium tris(dithiolene) complexes. Crucially we demonstrate that solutions of 1-4 in SO2, a uniquely polar nuclear spin-free solvent, reveal T2 values of up to 152(6) μs, comparable to the best molecular qubit candidates. Upon transitioning to vanadyl species from the tris(dithiolene) analogues, we observe a remarkable order of magnitude increase in T1, attributed to stronger solute-solvent interactions with the polar vanadium-oxo moiety. Simultaneously, we detect a small decrease in T2 for the vanadyl analogues relative to the tris(dithiolene) complexes. We attribute this decrease to the absence of one nuclear spin-free ligand, which served to shield the vanadium centers against solvent nuclear spins. Our results highlight new design principles for long T1 and T2 times by demonstrating the efficacy of ligand-based tuning of solute-solvent interactions.

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DO - 10.1021/jacs.6b08467

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AN - SCOPUS:84994494407

SN - 0002-7863

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JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

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ER -

Long Coherence Times in Nuclear Spin-Free Vanadyl Qubits

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Long Coherence Times in Nuclear Spin-Free Vanadyl Qubits

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CCDC 1521579: Experimental Crystal Structure Determination

CCDC 1521580: Experimental Crystal Structure Determination

CCDC 1521582: Experimental Crystal Structure Determination

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