1
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Martinez R, Jackson CE, Üngör Ö, van Tol J, Zadrozny JM. Impact of ligand chlorination and counterion tuning on high-field spin relaxation in a series of V(IV) complexes. Dalton Trans 2023. [PMID: 37485670 DOI: 10.1039/d3dt01274c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Methods of controlling spin coherence by molecular design are essential to efforts to develop molecular qubits for quantum information and sensing applications. In this manuscript, we perform the first studies of how arrangements of 35/37Cl nuclear spins in the ligand shell and counterion selection affect the coherent spin dynamics of V(IV) complexes at a high magnetic field. We prepared eight derivatives of the vanadium triscatecholate complex with varying arrangements of 35/37Cl substitution on the catechol backbone and R3NH+ counterions (R = Et, n-Bu, n-Hex) and investigated these species via structural and spectroscopic methods. Hahn-echo pulsed electron paramagnetic resonance (EPR) experiments at high-frequency (120 GHz) and field (ca. 4.4 T) were used to extract the phase-memory relaxation time (Tm) and spin-lattice relaxation (T1) times of the series of complexes. We found Tm values ranging from 4.8 to 1.1 μs in the temperature range of 5 to 40 K, varying by approximately 20% as a function of substitutional pattern. In-depth analysis of the results herein and comparison with related studies of brominated analogues disproves multiple hypothesized mechanisms for Tm control. Ultimately, we propose that more specific properties of the halogen atoms, e.g. the chemical shift, V⋯Cl hyperfine coupling, and quadrupolar coupling, could be contributing to the V(IV) Tm time.
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Affiliation(s)
- Roxanna Martinez
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
| | - Cassidy E Jackson
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
| | - Ökten Üngör
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
| | - Johan van Tol
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA
| | - Joseph M Zadrozny
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
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2
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Santanni F, Briganti M, Serrano G, Salvadori E, Veneri A, Batistoni C, Russi SF, Menichetti S, Mannini M, Chiesa M, Sorace L, Sessoli R. VdW Mediated Strong Magnetic Exchange Interactions in Chains of Hydrogen-Free Sublimable Molecular Qubits. JACS AU 2023; 3:1250-1262. [PMID: 37124308 PMCID: PMC10131211 DOI: 10.1021/jacsau.3c00121] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 03/31/2023] [Accepted: 03/31/2023] [Indexed: 05/03/2023]
Abstract
Sulfur-rich molecular complexes of dithiolene-like ligands are appealing candidates as molecular spin qubits because spin coherence properties are enhanced in hydrogen-free environments. Herein, we employ the hydrogen-free mononegative 1,3,2-dithiazole-4-thione-5-thiolate (dttt-) ligand as an alternative to common dinegative dithiolate ligands. We report the first synthesis and structural characterization of its Cu2+, Ni2+, and Pt2+ neutral complexes. The XPS analysis of thermal deposition of [Cu(dttt)2] in UHV conditions indicates that films of intact molecules can be deposited on surfaces by sublimation. Thanks to a combined approach employing DC magnetometry and DFT calculations, we highlighted AF exchange interactions of 108 cm-1 and 36 cm-1 attributed to the two different polymorph phases. These couplings are exclusively mediated by S···S VdW interactions, which are facilitated by the absence of counterions and made particularly efficient by the diffuse electron density on S atoms. Furthermore, the spin dynamics of solid-state magnetically diluted samples was investigated. The longest observed T m is 2.3 μs at 30 K, which significantly diverges from the predicted T m > 100 μs. These results point to the diluting matrix severely affecting the coherence lifetime of Cu2+ species via different factors, such as the contributions of neighboring 14N nuclei and the formation of radical impurities in a non-completely controllable way. However, the ease of processing [Cu(dttt)2] via thermal sublimation can allow dispersion in matrices better suited for coherent spin manipulation of isolated molecules and the realization of AF-coupled VdW structures on surfaces.
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Affiliation(s)
- Fabio Santanni
- Dipartimento
di Chimica “Ugo Schiff” - DICUS, Università degli Studi di Firenze, Via della Lastruccia 3-13, I-50019 Sesto Fiorentino, Firenze, Italy
- Consorzio
Interuniversitario Nazionale di Scienza e Tecnologia dei Materiali
- INSTM, Via G. Giusti
9, I-50121 Firenze, Italy
| | - Matteo Briganti
- Dipartimento
di Chimica “Ugo Schiff” - DICUS, Università degli Studi di Firenze, Via della Lastruccia 3-13, I-50019 Sesto Fiorentino, Firenze, Italy
- Consorzio
Interuniversitario Nazionale di Scienza e Tecnologia dei Materiali
- INSTM, Via G. Giusti
9, I-50121 Firenze, Italy
| | - Giulia Serrano
- Consorzio
Interuniversitario Nazionale di Scienza e Tecnologia dei Materiali
- INSTM, Via G. Giusti
9, I-50121 Firenze, Italy
- Dipartimento
di Ingegneria Industriale - DIEF, Università
degli Studi di Firenze, Via Santa Marta 3, I-50139 Firenze, Italy
| | - Enrico Salvadori
- Consorzio
Interuniversitario Nazionale di Scienza e Tecnologia dei Materiali
- INSTM, Via G. Giusti
9, I-50121 Firenze, Italy
- Dipartimento
di Chimica e NIS Centre, Università
di Torino, Via P. Giuria 7, I-10125 Torino, Italy
| | - Alessandro Veneri
- Dipartimento
di Chimica “Ugo Schiff” - DICUS, Università degli Studi di Firenze, Via della Lastruccia 3-13, I-50019 Sesto Fiorentino, Firenze, Italy
- Consorzio
Interuniversitario Nazionale di Scienza e Tecnologia dei Materiali
- INSTM, Via G. Giusti
9, I-50121 Firenze, Italy
| | - Chiara Batistoni
- Consorzio
Interuniversitario Nazionale di Scienza e Tecnologia dei Materiali
- INSTM, Via G. Giusti
9, I-50121 Firenze, Italy
| | - Sofia F. Russi
- Dipartimento
di Chimica e NIS Centre, Università
di Torino, Via P. Giuria 7, I-10125 Torino, Italy
| | - Stefano Menichetti
- Dipartimento
di Chimica “Ugo Schiff” - DICUS, Università degli Studi di Firenze, Via della Lastruccia 3-13, I-50019 Sesto Fiorentino, Firenze, Italy
- Consorzio
Interuniversitario Nazionale di Scienza e Tecnologia dei Materiali
- INSTM, Via G. Giusti
9, I-50121 Firenze, Italy
| | - Matteo Mannini
- Dipartimento
di Chimica “Ugo Schiff” - DICUS, Università degli Studi di Firenze, Via della Lastruccia 3-13, I-50019 Sesto Fiorentino, Firenze, Italy
- Consorzio
Interuniversitario Nazionale di Scienza e Tecnologia dei Materiali
- INSTM, Via G. Giusti
9, I-50121 Firenze, Italy
| | - Mario Chiesa
- Consorzio
Interuniversitario Nazionale di Scienza e Tecnologia dei Materiali
- INSTM, Via G. Giusti
9, I-50121 Firenze, Italy
- Dipartimento
di Chimica e NIS Centre, Università
di Torino, Via P. Giuria 7, I-10125 Torino, Italy
| | - Lorenzo Sorace
- Dipartimento
di Chimica “Ugo Schiff” - DICUS, Università degli Studi di Firenze, Via della Lastruccia 3-13, I-50019 Sesto Fiorentino, Firenze, Italy
- Consorzio
Interuniversitario Nazionale di Scienza e Tecnologia dei Materiali
- INSTM, Via G. Giusti
9, I-50121 Firenze, Italy
| | - Roberta Sessoli
- Dipartimento
di Chimica “Ugo Schiff” - DICUS, Università degli Studi di Firenze, Via della Lastruccia 3-13, I-50019 Sesto Fiorentino, Firenze, Italy
- Consorzio
Interuniversitario Nazionale di Scienza e Tecnologia dei Materiali
- INSTM, Via G. Giusti
9, I-50121 Firenze, Italy
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3
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Amdur MJ, Mullin KR, Waters MJ, Puggioni D, Wojnar MK, Gu M, Sun L, Oyala PH, Rondinelli JM, Freedman DE. Chemical control of spin-lattice relaxation to discover a room temperature molecular qubit. Chem Sci 2022; 13:7034-7045. [PMID: 35774181 PMCID: PMC9200133 DOI: 10.1039/d1sc06130e] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 05/16/2022] [Indexed: 11/21/2022] Open
Abstract
The second quantum revolution harnesses exquisite quantum control for a slate of diverse applications including sensing, communication, and computation. Of the many candidates for building quantum systems, molecules offer both tunability and specificity, but the principles to enable high temperature operation are not well established. Spin-lattice relaxation, represented by the time constant T 1, is the primary factor dictating the high temperature performance of quantum bits (qubits), and serves as the upper limit on qubit coherence times (T 2). For molecular qubits at elevated temperatures (>100 K), molecular vibrations facilitate rapid spin-lattice relaxation which limits T 2 to well below operational minimums for certain quantum technologies. Here we identify the effects of controlling orbital angular momentum through metal coordination geometry and ligand rigidity via π-conjugation on T 1 relaxation in three four-coordinate Cu2+ S = ½ qubit candidates: bis(N,N'-dimethyl-4-amino-3-penten-2-imine) copper(ii) (Me2Nac)2 (1), bis(acetylacetone)ethylenediamine copper(ii) Cu(acacen) (2), and tetramethyltetraazaannulene copper(ii) Cu(tmtaa) (3). We obtain significant T 1 improvement upon changing from tetrahedral to square planar geometries through changes in orbital angular momentum. T 1 is further improved with greater π-conjugation in the ligand framework. Our electronic structure calculations reveal that the reduced motion of low energy vibrations in the primary coordination sphere slows relaxation and increases T 1. These principles enable us to report a new molecular qubit candidate with room temperature T 2 = 0.43 μs, and establishes guidelines for designing novel qubit candidates operating above 100 K.
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Affiliation(s)
- M Jeremy Amdur
- Department of Chemistry, Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA
| | - Kathleen R Mullin
- Department of Materials Science and Engineering, Northwestern University Evanston Illinois 60208 USA
| | - Michael J Waters
- Department of Materials Science and Engineering, Northwestern University Evanston Illinois 60208 USA
| | - Danilo Puggioni
- Department of Materials Science and Engineering, Northwestern University Evanston Illinois 60208 USA
| | - Michael K Wojnar
- Department of Chemistry, Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA
| | - Mingqiang Gu
- Department of Materials Science and Engineering, Northwestern University Evanston Illinois 60208 USA
| | - Lei Sun
- Center for Nanoscale Materials, Argonne National Laboratory Argonne Illinois 60439 USA
| | - Paul H Oyala
- Division of Chemistry and Chemical Engineering, California Institute of Technology Pasadena California 91125 USA
| | - James M Rondinelli
- Department of Materials Science and Engineering, Northwestern University Evanston Illinois 60208 USA
| | - Danna E Freedman
- Department of Chemistry, Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA .,Department of Chemistry, Northwestern University Evanston Illinois 60208 USA
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4
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Ghosh S, Kamilya S, Mehta S, Herchel R, Kiskin M, Veber S, Fedin M, Mondal A. Effect of Ligand Chain Length for Tuning of Molecular Dimensionality and Magnetic Relaxation in Redox Active Cobalt(II) EDOT Complexes (EDOT = 3,4-Ethylenedioxythiophene). Chem Asian J 2022; 17:e202200404. [PMID: 35617522 DOI: 10.1002/asia.202200404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 05/17/2022] [Indexed: 11/07/2022]
Abstract
Four cobalt(II) complexes, [Co(L1)2(NCX)2(MeOH)2] (X = S (1), Se (2)) and {[Co(L2)2(NCX)2]}n (X = S (3), Se (4)) (L1 = 2,5dipyridyl-3,4,-ethylenedioxylthiophene and L2 = 2,5diethynylpyridinyl-3,4-ethylenedioxythiophene), were synthesized by incorporating ethylenedioxythiophene based redox-active luminescence ligands. All these complexes have been well characterized using single-crystal X-ray diffraction analyses, spectroscopic and magnetic investigations. Magneto-structural studies showed that 1 and 2 adopt a mononuclear structure with CoN4O2 octahedral coordination geometry while 3 and 4 have a 2D [4 x 4] rhombic grid coordination networks (CNs) where each cobalt(II) center is in a CoN6 octahedral coordination environment. Static magnetic measurements reveal that all four complexes displayed a high spin (HS) (S = 3/2) state between 2 and 280 K which was further confirmed by X-band and Q-band EPR studies. Remarkably, along with the molecular dimensionality (0D and 2D) the modification in the axial coligands lead to a significant difference in the dynamic magnetic properties of the monomers and CNs at low temperatures. All complexes display slow magnetic relaxation behavior under an external dc magnetic field. For the complexes with NCS- as coligand observed higher energy barrier for spin reversal in comparison to the complexes with NCSe- as coligand, while mononuclear complex 1 exhibited a higher energy barrier than that of CN 3. Theoretical calculations at the DFT and CASSCF level of theory have been performed to get more insight into the electronic structure and magnetic properties of all four complexes.
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Affiliation(s)
- Subrata Ghosh
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Sir C. V. Raman Road, 560012, Bangalore, India
| | - Sujit Kamilya
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Sir C. V. Raman Road, 560012, Bangalore, India
| | - Sakshi Mehta
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Sir C. V. Raman Road, 560012, Bangalore, India
| | - Radovan Herchel
- Department of Inorganic Chemistry, Faculty of Science, Palacký University, CZ-771 46, Olomouc, Czech Republic
| | - Mikhail Kiskin
- N. S. Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, Leninsky Prosp. 31, 119991, Moscow, Russia
| | - Sergey Veber
- International Tomography Center of the Siberian Branch of the Russian Academy of Sciences, Institutskaya Str. 3a, 630090, Novosibirsk, Russia
- Novosibirsk State University, Pirogova Str. 1, 630090, Novosibirsk, Russia
| | - Matvey Fedin
- International Tomography Center of the Siberian Branch of the Russian Academy of Sciences, Institutskaya Str. 3a, 630090, Novosibirsk, Russia
- Novosibirsk State University, Pirogova Str. 1, 630090, Novosibirsk, Russia
| | - Abhishake Mondal
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Sir C. V. Raman Road, 560012, Bangalore, India
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5
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Mahapatro SN, Hovey TA, Ngendahimana T, Eaton SS, Eaton GR. Electron paramagnetic resonance characterization and electron spin relaxation of manganate ion in glassy alkaline LiCl solution and doped into Cs2SO4. J Inorg Biochem 2022; 229:111732. [DOI: 10.1016/j.jinorgbio.2022.111732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/23/2021] [Accepted: 01/15/2022] [Indexed: 11/26/2022]
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6
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Horii Y, Makino M, Yamamoto T, Tatsumi S, Suzuki H, Noguchi M, Yoshida T, Kajiwara T, Li ZY, Yamashita M. Solid polymorphism and dynamic magnetic properties of a dodecylated vanadyl–porphyrinato complex: spin–lattice relaxations modulated by phase stabilisation. Inorg Chem Front 2022. [DOI: 10.1039/d2qi01607a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Phase stabilisation elongates spin–lattice relaxation times.
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Affiliation(s)
- Yoji Horii
- The Department of Chemistry, Faculty of Science, Nara Women's University, Nara 6308506, Japan
| | - Momo Makino
- The Department of Chemistry, Faculty of Science, Nara Women's University, Nara 6308506, Japan
| | - Taro Yamamoto
- Department of Chemistry, Kindai University, 3-4-1 Kowakae, Higashiosaka, Osaka 577-8502, Japan
| | - Shoichi Tatsumi
- Department of Chemistry, Kindai University, 3-4-1 Kowakae, Higashiosaka, Osaka 577-8502, Japan
| | - Hal Suzuki
- Department of Chemistry, Kindai University, 3-4-1 Kowakae, Higashiosaka, Osaka 577-8502, Japan
| | - Mariko Noguchi
- Graduate School of Integrated Basic Sciences, Nihon University, 3-25-40 Sakurajosui, Setagaya-ku, Tokyo 156-8550, Japan
| | - Takefumi Yoshida
- Innovation Research Center for Fuel Cells, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
| | - Takashi Kajiwara
- The Department of Chemistry, Faculty of Science, Nara Women's University, Nara 6308506, Japan
| | - Zhao-Yang Li
- School of Materials Science and Engineering, Nankai University, Tianjin 300350, China
| | - Masahiro Yamashita
- School of Materials Science and Engineering, Nankai University, Tianjin 300350, China
- Graduate School of Science, Tohoku University, 6-3 Aramaki-Aza-Aoba Aoba-ku, Sendai, Miyagi, 980-8578, Japan
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7
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Mirzoyan R, Kazmierczak NP, Hadt RG. Deconvolving Contributions to Decoherence in Molecular Electron Spin Qubits: A Dynamic Ligand Field Approach. Chemistry 2021; 27:9482-9494. [PMID: 33855760 DOI: 10.1002/chem.202100845] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Indexed: 12/16/2022]
Abstract
In the past decade, transition metal complexes have gained momentum as electron spin-based quantum bit (qubit) candidates due to their synthetic tunability and long achievable coherence times. The decoherence of magnetic quantum states imposes a limit on the use of these qubits for quantum information technologies, such as quantum computing, sensing, and communication. With rapid recent development in the field of molecular quantum information science, a variety of chemical design principles for prolonging coherence in molecular transition metal qubits have been proposed. Here the spin-spin, motional, and spin-phonon regimes of decoherence are delineated, outlining design principles for each. It is shown how dynamic ligand field models can provide insights into the intramolecular vibrational contributions in the spin-phonon decoherence regime. This minireview aims to inform the development of molecular quantum technologies tailored for different environments and conditions.
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Affiliation(s)
- Ruben Mirzoyan
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Nathanael P Kazmierczak
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Ryan G Hadt
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA
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8
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López-Cabrelles J, Escalera-Moreno L, Hu Z, Prima-García H, Espallargas GM, Gaita-Ariño A, Coronado E. Near Isotropic D4d Spin Qubits as Nodes of a Gd(III)-Based Metal-Organic Framework. Inorg Chem 2021; 60:8575-8580. [PMID: 34096277 PMCID: PMC8291595 DOI: 10.1021/acs.inorgchem.1c00504] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Embedding coherent spin motifs in reproducible molecular building blocks is a promising pathway for the realization of quantum technologies. Three-dimensional (3D) MOFs are a versatile platform for the rational design of extended structures employing coordination chemistry. Here, we report the synthesis and characterization of a gadolinium(III)-based MOF, [Gd(bipyNO)4](TfO)3·xMeOH (bipyNO = bipyridine,N,N'-dioxide; TfO = triflate; and MeOH = methanol) (quMOF-1), which presents a unique coordination geometry that leads to a tiny magnetic anisotropy (in terms of D, an equivalent zero-field splitting would be achieved by D = 0.006 cm-1) even compared with regular Gd(III) complexes. Pulsed electron paramagnetic resonance experiments on its magnetically diluted samples confirm the preservation of quantum coherence of single Gd(III) qubit units in this 3D extended molecular architecture (T2 = 612 ns and T1 = 66 μs at 3.5 K), which allows for the detection of Rabi oscillations at 40 K.
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Affiliation(s)
- Javier López-Cabrelles
- Instituto de Ciencia Molecular (ICMol), Universitat de València, c/Catedrático José Beltrán, 2, 46980 Paterna, Spain
| | - Luis Escalera-Moreno
- Instituto de Ciencia Molecular (ICMol), Universitat de València, c/Catedrático José Beltrán, 2, 46980 Paterna, Spain
| | - Ziqi Hu
- Instituto de Ciencia Molecular (ICMol), Universitat de València, c/Catedrático José Beltrán, 2, 46980 Paterna, Spain
| | - Helena Prima-García
- Instituto de Ciencia Molecular (ICMol), Universitat de València, c/Catedrático José Beltrán, 2, 46980 Paterna, Spain
| | - Guillermo Mínguez Espallargas
- Instituto de Ciencia Molecular (ICMol), Universitat de València, c/Catedrático José Beltrán, 2, 46980 Paterna, Spain
| | - Alejandro Gaita-Ariño
- Instituto de Ciencia Molecular (ICMol), Universitat de València, c/Catedrático José Beltrán, 2, 46980 Paterna, Spain
| | - Eugenio Coronado
- Instituto de Ciencia Molecular (ICMol), Universitat de València, c/Catedrático José Beltrán, 2, 46980 Paterna, Spain
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9
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Santanni F, Albino A, Atzori M, Ranieri D, Salvadori E, Chiesa M, Lunghi A, Bencini A, Sorace L, Totti F, Sessoli R. Probing Vibrational Symmetry Effects and Nuclear Spin Economy Principles in Molecular Spin Qubits. Inorg Chem 2021; 60:140-151. [PMID: 33305944 PMCID: PMC7872321 DOI: 10.1021/acs.inorgchem.0c02573] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Indexed: 12/18/2022]
Abstract
The selection of molecular spin qubits with a long coherence time, Tm, is a central task for implementing molecule-based quantum technologies. Even if a sufficiently long Tm can be achieved through an efficient synthetic strategy and ad hoc experimental measurement procedures, many factors contributing to the loss of coherence still need to be thoroughly investigated and understood. Vibrational properties and nuclear spins of hydrogens are two of them. The former plays a paramount role, but a detailed theoretical investigation aimed at studying their effects on the spin dynamics of molecular complexes such as the benchmark phthalocyanine (Pc) is still missing, whereas the effect of the latter deserves to be examined in detail for such a class of compounds. In this work, we adopted a combined theoretical and experimental approach to investigate the relaxation properties of classical [Cu(Pc)] and a CuII complex based on the ligand tetrakis(thiadiazole)porphyrazine (H2TTDPz), characterized by a hydrogen-free molecular structure. Systematic calculations of molecular vibrations exemplify the effect of normal modes on the spin-lattice relaxation process, unveiling a different contribution to T1 depending on the symmetry of normal modes. Moreover, we observed that an appreciable Tm enhancement could be achieved by removing hydrogens from the ligand.
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Affiliation(s)
- Fabio Santanni
- Dipartimento
di Chimica “Ugo Schiff” & INSTM RU, Università degli Studi di Firenze, Via della Lastruccia 3, I50019 Sesto Fiorentino, Firenze) Italy
| | - Andrea Albino
- Dipartimento
di Chimica “Ugo Schiff” & INSTM RU, Università degli Studi di Firenze, Via della Lastruccia 3, I50019 Sesto Fiorentino, Firenze) Italy
| | - Matteo Atzori
- Laboratoire
National des Champs Magnétiques Intenses (LNCMI), Univ. Grenoble
Alpes, INSA Toulouse, Univ. Toulouse Paul
Sabatier, EMFL, CNRS, F38043 Grenoble, France
| | - Davide Ranieri
- Dipartimento
di Chimica “Ugo Schiff” & INSTM RU, Università degli Studi di Firenze, Via della Lastruccia 3, I50019 Sesto Fiorentino, Firenze) Italy
| | - Enrico Salvadori
- Dipartimento
di Chimica e NIS Centre, Università
di Torino, Via P. Giuria 7, I10125 Torino, Italy
| | - Mario Chiesa
- Dipartimento
di Chimica e NIS Centre, Università
di Torino, Via P. Giuria 7, I10125 Torino, Italy
| | - Alessandro Lunghi
- School
of Physics, AMBER and CRANN Institute, Trinity
College, Dublin 2, Ireland
| | - Andrea Bencini
- Dipartimento
di Chimica “Ugo Schiff” & INSTM RU, Università degli Studi di Firenze, Via della Lastruccia 3, I50019 Sesto Fiorentino, Firenze) Italy
| | - Lorenzo Sorace
- Dipartimento
di Chimica “Ugo Schiff” & INSTM RU, Università degli Studi di Firenze, Via della Lastruccia 3, I50019 Sesto Fiorentino, Firenze) Italy
| | - Federico Totti
- Dipartimento
di Chimica “Ugo Schiff” & INSTM RU, Università degli Studi di Firenze, Via della Lastruccia 3, I50019 Sesto Fiorentino, Firenze) Italy
| | - Roberta Sessoli
- Dipartimento
di Chimica “Ugo Schiff” & INSTM RU, Università degli Studi di Firenze, Via della Lastruccia 3, I50019 Sesto Fiorentino, Firenze) Italy
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10
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Follmer AH, Ribson RD, Oyala PH, Chen GY, Hadt RG. Understanding Covalent versus Spin-Orbit Coupling Contributions to Temperature-Dependent Electron Spin Relaxation in Cupric and Vanadyl Phthalocyanines. J Phys Chem A 2020; 124:9252-9260. [PMID: 33112149 DOI: 10.1021/acs.jpca.0c07860] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Recent interest in transition-metal complexes as potential quantum bits (qubits) has reinvigorated the investigation of fundamental contributions to electron spin relaxation in various ligand scaffolds. From quantum computers to chemical and biological sensors, interest in leveraging the quantum properties of these molecules has opened a discussion of the requirements to maintain coherence over a large temperature range, including near room temperature. Here we compare temperature-, magnetic field position-, and concentration-dependent electron spin relaxation in copper(II) phthalocyanine (CuPc) and vanadyl phthalocyanine (VOPc) doped into diamagnetic hosts. While VOPc demonstrates coherence up to room temperature, CuPc coherence times become rapidly T1-limited with increasing temperature, despite featuring a more covalent ground-state wave function than VOPc. As rationalized by a ligand field model, this difference is ascribed to different spin-orbit coupling (SOC) constants for Cu(II) versus V(IV). The manifestation of SOC contributions to spin-phonon coupling and electron spin relaxation in different ligand fields is discussed, allowing for a further understanding of the competing roles of SOC and covalency in electron spin relaxation.
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Affiliation(s)
- Alec H Follmer
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Ryan D Ribson
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Paul H Oyala
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Grace Y Chen
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Ryan G Hadt
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
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11
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Mathivathanan L, Rogez G, Ben Amor N, Robert V, Raptis RG, Boudalis AK. Origin of Ferromagnetism and Magnetic Anisotropy in a Family of Copper(II) Triangles. Chemistry 2020; 26:12769-12784. [DOI: 10.1002/chem.202001028] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Indexed: 11/11/2022]
Affiliation(s)
- Logesh Mathivathanan
- Department of Chemistry and Biochemistry and the Biomolecular Sciences Institute Florida International University Miami FL 33199 USA
| | - Guillaume Rogez
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS) CNRS/Université de Strasbourg UMR 7504 67000 Strasbourg France
| | - Nadia Ben Amor
- Laboratoire de Chimie et Physique Quantiques UMR 5626 CNRS/Université Paul Sabatier—Bat. 3R1B4 118 route de Narbonne 31062, Cedex 09 Toulouse France
| | - Vincent Robert
- Institut de Chimie de Strasbourg (UMR 7177, CNRS-Unistra) Université de Strasbourg 4 rue Blaise Pascal, CS 90032 67081 Strasbourg France
| | - Raphael G. Raptis
- Department of Chemistry and Biochemistry and the Biomolecular Sciences Institute Florida International University Miami FL 33199 USA
| | - Athanassios K. Boudalis
- Institut de Chimie de Strasbourg (UMR 7177, CNRS-Unistra) Université de Strasbourg 4 rue Blaise Pascal, CS 90032 67081 Strasbourg France
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12
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Johnson SH, Jackson CE, Zadrozny JM. Programmable Nuclear-Spin Dynamics in Ti(IV) Coordination Complexes. Inorg Chem 2020; 59:7479-7486. [PMID: 32302112 PMCID: PMC8109263 DOI: 10.1021/acs.inorgchem.0c00244] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Interstitial patterning of nuclear spins is a nascent design principle for controlling electron spin superposition lifetimes in open-shell complexes and solid-state defects. Herein we report the first test of the impact of the patterning principle on ligand-based nuclear spin dynamics. We test how substitutional patterning of 1H and 79/81Br nuclear spins on ligands modulates proton nuclear spin dynamics in the ligand shell of metal complexes. To do so, we studied the 1H nuclear magnetic resonance relaxation times (T1 and T2) of a series of eight polybrominated catechol ligands and six complexes formed by coordination of the ligands to a Ti(IV) ion. These studies reveal that 1H T1 values can be enhanced in the individual ligands by a factor of 4 (from 10.8(3) to 43(5) s) as a function of substitution pattern, reaching the maximum value for 3,4,6-tribromocatechol. The T2 for 1H is also enhanced by a factor of 4, varying by ∼14 s across the series. When complexed, the impact of the patterning design strategy on nuclear spin dynamics is amplified and 1H T1 and T2 values vary by over an order of magnitude. Importantly, the general trends observed in the ligands also match those when complexed. Hence, these results demonstrate a new design principle to control 1H spin dynamics in metal complexes through pattern-based design strategies in the ligand shell.
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Affiliation(s)
- Spencer H Johnson
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Cassidy E Jackson
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Joseph M Zadrozny
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
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13
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Ghosh S, Kamilya S, Das M, Mehta S, Boulon ME, Nemec I, Rouzières M, Herchel R, Mondal A. Effect of Coordination Geometry on Magnetic Properties in a Series of Cobalt(II) Complexes and Structural Transformation in Mother Liquor. Inorg Chem 2020; 59:7067-7081. [DOI: 10.1021/acs.inorgchem.0c00538] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Subrata Ghosh
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Sir C. V. Raman Road, Bangalore 560012, India
| | - Sujit Kamilya
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Sir C. V. Raman Road, Bangalore 560012, India
| | - Mayurika Das
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Sir C. V. Raman Road, Bangalore 560012, India
| | - Sakshi Mehta
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Sir C. V. Raman Road, Bangalore 560012, India
| | - Marie-Emmanuelle Boulon
- Photon Science Institute, Alan Turing Building, office 3.315, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Ivan Nemec
- Department of Inorganic Chemistry, Faculty of Science, Palacký University, 17. listopadu 12, CZ-771 46 Olomouc, Czech Republic
- Central European Institute of Technology, CEITEC BUT, Technická 3058/10, 61600 Brno, Czech Republic
| | - Mathieu Rouzières
- Univ. Bordeaux, CNRS, Centre de Recherche Paul Pascal, CRPP, UMR 5031, 33600 Pessac, France
| | - Radovan Herchel
- Department of Inorganic Chemistry, Faculty of Science, Palacký University, 17. listopadu 12, CZ-771 46 Olomouc, Czech Republic
| | - Abhishake Mondal
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Sir C. V. Raman Road, Bangalore 560012, India
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14
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Chen J, Hu C, Stanton JF, Hill S, Cheng HP, Zhang XG. Decoherence in Molecular Electron Spin Qubits: Insights from Quantum Many-Body Simulations. J Phys Chem Lett 2020; 11:2074-2078. [PMID: 32097549 DOI: 10.1021/acs.jpclett.0c00193] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Quantum states are described by wave functions whose phases cannot be directly measured but which play a vital role in quantum effects such as interference and entanglement. The loss of the relative phase information, termed decoherence, arises from the interactions between a quantum system and its environment. Decoherence is perhaps the biggest obstacle on the path to reliable quantum computing. Here we show that decoherence occurs even in an isolated molecule, although not all phase information is lost, via a theoretical study of a central electron spin qubit interacting with nearby nuclear spins in prototypical magnetic molecules. The residual coherence, which is molecule-dependent, provides a microscopic rationalization for the nuclear spin diffusion barrier proposed to explain experiments. The contribution of nearby molecules to the decoherence has a nontrivial dependence on separation, peaking at intermediate distances. Molecules that are far away affect only the long-time behavior. Because the residual coherence is simple to calculate and correlates well with the coherence time, it can be used as a descriptor for coherence in magnetic molecules. This work will help establish design principles for enhancing coherence in molecular spin qubits and serve to motivate further theoretical work.
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Affiliation(s)
- Jia Chen
- Department of Physics, University of Florida, Gainesville, Florida 32611, United States
- Quantum Theory Project, University of Florida, Gainesville, Florida 32611, United States
- Center for Molecular Magnetic Quantum Materials, Gainesville, Florida, United States
| | - Cong Hu
- Department of Physics, University of Connecticut, Storrs, Connecticut 06269, United States
| | - John F Stanton
- Quantum Theory Project, University of Florida, Gainesville, Florida 32611, United States
- Center for Molecular Magnetic Quantum Materials, Gainesville, Florida, United States
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Stephen Hill
- Center for Molecular Magnetic Quantum Materials, Gainesville, Florida, United States
- Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, United States
| | - Hai-Ping Cheng
- Department of Physics, University of Florida, Gainesville, Florida 32611, United States
- Quantum Theory Project, University of Florida, Gainesville, Florida 32611, United States
- Center for Molecular Magnetic Quantum Materials, Gainesville, Florida, United States
| | - Xiao-Guang Zhang
- Department of Physics, University of Florida, Gainesville, Florida 32611, United States
- Quantum Theory Project, University of Florida, Gainesville, Florida 32611, United States
- Center for Molecular Magnetic Quantum Materials, Gainesville, Florida, United States
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15
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Jackson CE, Lin CY, van Tol J, Zadrozny JM. Orientation dependence of phase memory relaxation in the V(IV) ion at high frequencies. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2019.137034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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16
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Mapping Magnetic Properties and Relaxation in Vanadium(IV) Complexes with Lanthanides by Electron Paramagnetic Resonance. Molecules 2019; 24:molecules24244582. [PMID: 31847326 PMCID: PMC6943608 DOI: 10.3390/molecules24244582] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 11/29/2019] [Accepted: 12/11/2019] [Indexed: 11/23/2022] Open
Abstract
Vanadium(IV) complexes are actively studied as potential candidates for molecular spin qubits operating at room temperatures. They have longer electron spin decoherence times than many other transition ions, being the key property for applications in quantum information processing. In most cases reported to date, the molecular complexes were optimized through the design for this purpose. In this work, we investigate the relaxation properties of vanadium(IV) ions incorporated in complexes with lanthanides using electron paramagnetic resonance (EPR). In all cases, the VO6 moieties with no nuclear spins in the first coordination sphere are addressed. We develop and implement the approaches for facile diagnostics of relaxation characteristics in individual VO6 moieties of such compounds. Remarkably, the estimated relaxation times are found to be close to those of other vanadium-based qubits obtained previously. In the future, a synergistic combination of qubit-friendly properties of vanadium ions with single-molecule magnetism and luminescence of lanthanides can be pursued to realize new functionalities of such materials.
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17
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Ngendahimana T, Ayikpoe R, Latham JA, Eaton GR, Eaton SS. Structural insights for vanadium catecholates and iron‑sulfur clusters obtained from multiple data analysis methods applied to electron spin relaxation data. J Inorg Biochem 2019; 201:110806. [PMID: 31505439 PMCID: PMC6859209 DOI: 10.1016/j.jinorgbio.2019.110806] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 08/06/2019] [Accepted: 08/21/2019] [Indexed: 01/22/2023]
Abstract
Electron paramagnetic resonance (EPR) inversion recovery curves for vanadium catecholates and iron‑sulfur clusters were analyzed with three models: the sum of two exponentials, a stretched exponential, and a model-free distribution of exponentials (UPEN). For all data sets studied fits with a stretched exponential were statistically indistinguishable from the sum of two exponentials, and were significantly better than for single exponentials. UPEN provides insights into the structures of the distributions. For a vanadium(IV) tris catecholate the distribution of relaxation rates calculated with UPEN shows the contribution from spectral diffusion at low temperatures. The energy of the local mode for this complex, found from the temperature dependence of the spin lattice relaxation, is consistent with values expected for a metal-ligand vibration. For the [2Fe-2S]+ cluster in pyruvate formate lyase activating enzyme (PFL-AE) the small stretched exponential β values (0.3) at low temperature and the distributions calculated with UPEN reflect the contribution from a second rapidly relaxing species that could be difficult to detect by continuous wave EPR. The distributions in 1/T1 for the [4Fe-4S]+ clusters in Mycofactocin maturase were about a factor of four wider than for the three other systems studied. The very broad distribution of relaxation rates may be due to protein mobility and distributions in electronic energies and local environments for the clusters. UPEN provides insight into several situations that can result in low values of stretch parameter β including contributions from spectral diffusion, overlapping signals from distinguishable clusters, or very wide distributions.
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Affiliation(s)
- Thacien Ngendahimana
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, United States of America
| | - Richard Ayikpoe
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, United States of America
| | - John A Latham
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, United States of America
| | - Gareth R Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, United States of America
| | - Sandra S Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, United States of America..
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18
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Escalera-Moreno L, Baldoví JJ. Unveiling the Effect of Magnetic Noise in the Coherence of Single-Molecule Quantum Processors. Front Chem 2019; 7:662. [PMID: 31632953 PMCID: PMC6779859 DOI: 10.3389/fchem.2019.00662] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 09/17/2019] [Indexed: 11/13/2022] Open
Abstract
Quantum bits (qubits) constitute the most elementary building-blocks of any quantum technology, where information is stored and processed in the form of quantum superpositions between discrete energy levels. In particular, the fabrication of quantum processors is a key long-term goal that will allow us conducting specific tasks much more efficiently than the most powerful classical computers can do. Motivated by recent experiments in which three addressable spin qubits are defined on a potential single-molecule quantum processor, namely the [Gd(H2O)P5W30O110]12- polyoxometalate, we investigate the decohering effect of magnetic noise on the encoded quantum information. Our state-of-the-art model, which provides more accurate results than previous estimates, show a noticeable contribution of magnetic noise in limiting the survival timescale of the qubits. Yet, our results suggest that it might not be the only dephasing mechanism at play but other mechanisms, such as lattice vibrations and physical movement of magnetic nuclei, must be considered to understand the whole decoherence process.
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Affiliation(s)
| | - José J Baldoví
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany
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19
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Jackson CE, Lin CY, Johnson SH, van Tol J, Zadrozny JM. Nuclear-spin-pattern control of electron-spin dynamics in a series of V(iv) complexes. Chem Sci 2019; 10:8447-8454. [PMID: 31803424 PMCID: PMC6839508 DOI: 10.1039/c9sc02899d] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 07/27/2019] [Indexed: 12/28/2022] Open
Abstract
Achieving control of phase memory relaxation times (T m) in metal ions is an important goal of molecular spintronics. Herein we provide the first evidence that nuclear-spin patterning in the ligand shell is an important handle to modulate T m in metal ions. We synthesized and studied a series of five V(iv) complexes with brominated catecholate ligands, [V(C6H4-n Br n O2)3]2- (n = 0, 1, 2, and 4), where the 79/81Br and 1H nuclear spins are arranged in different substitutional patterns. High-field, high-frequency (120 GHz) pulsed electron paramagnetic resonance spectroscopic analysis of this series reveals a pattern-dependent variation in T m for the V(iv) ion. Notably, we show that it is possible for two molecules to have starkly different (by 50%) T m values despite the same chemical composition. Nuclear magnetic resonance analyses of the protons on the ligand shell suggest that relative chemical shift (δ), controlled by the patterning of nuclear spins, is an important underlying design principle. Here, having multiple ligand-based protons with nearly identical chemical shift values in the ligand shell will, ultimately, engender a short T m for the bound metal ion.
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Affiliation(s)
- Cassidy E Jackson
- Department of Chemistry , Colorado State University , Fort Collins , CO 80523 , USA .
| | - Chun-Yi Lin
- Department of Chemistry , Colorado State University , Fort Collins , CO 80523 , USA .
| | - Spencer H Johnson
- Department of Chemistry , Colorado State University , Fort Collins , CO 80523 , USA .
| | - Johan van Tol
- National High Magnetic Field Laboratory , Tallahassee , FL 32310 , USA
| | - Joseph M Zadrozny
- Department of Chemistry , Colorado State University , Fort Collins , CO 80523 , USA .
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20
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Fataftah MS, Krzyaniak MD, Vlaisavljevich B, Wasielewski MR, Zadrozny JM, Freedman DE. Metal-ligand covalency enables room temperature molecular qubit candidates. Chem Sci 2019; 10:6707-6714. [PMID: 31367325 PMCID: PMC6625489 DOI: 10.1039/c9sc00074g] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Accepted: 05/27/2019] [Indexed: 12/29/2022] Open
Abstract
Metal–ligand covalency enables observation of coherent spin dynamics to room temperature in a series of vanadium(iv) and copper(ii) catechol complexes.
Harnessing synthetic chemistry to design electronic spin-based qubits, the smallest unit of a quantum information system, enables us to probe fundamental questions regarding spin relaxation dynamics. We sought to probe the influence of metal–ligand covalency on spin–lattice relaxation, which comprises the upper limit of coherence time. Specifically, we studied the impact of the first coordination sphere on spin–lattice relaxation through a series of four molecules featuring V–S, V–Se, Cu–S, and Cu–Se bonds, the Ph4P+ salts of the complexes [V(C6H4S2)3]2– (1), [Cu(C6H4S2)2]2– (2), [V(C6H4Se2)3]2– (3), and [Cu(C6H4Se2)2]2– (4). The combined results of pulse electron paramagnetic resonance spectroscopy and ac magnetic susceptibility studies demonstrate the influence of greater M–L covalency, and consequently spin-delocalization onto the ligand, on elongating spin–lattice relaxation times. Notably, we observe the longest spin–lattice relaxation times in 2, and spin echos that survive until room temperature in both copper complexes (2 and 4).
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Affiliation(s)
- Majed S Fataftah
- Department of Chemistry , Northwestern University , Evanston , IL 60208 , USA . ;
| | - Matthew D Krzyaniak
- Department of Chemistry , Northwestern University , Evanston , IL 60208 , USA . ; .,The Institute for Sustainability and Energy at Northwestern , Northwestern University , Evanston , IL 60208 , USA
| | - Bess Vlaisavljevich
- Department of Chemistry , University of South Dakota , Vermillion , South Dakota 57069 , USA
| | - Michael R Wasielewski
- Department of Chemistry , Northwestern University , Evanston , IL 60208 , USA . ; .,The Institute for Sustainability and Energy at Northwestern , Northwestern University , Evanston , IL 60208 , USA
| | - Joseph M Zadrozny
- Department of Chemistry , Colorado State University , Fort Collins , Colorado 80523 , USA .
| | - Danna E Freedman
- Department of Chemistry , Northwestern University , Evanston , IL 60208 , USA . ;
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