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Teaser, summary, work performed and final results

Periodic Reporting for period 1 - CHIRALQUBIT (Antiferromagnetic spin-chiral triangles as decoherence-free qubits)

Teaser

Quantum Information Processing (QIP) is a groundbreaking new field with implications ranging from overcoming Moore\'s law to the security of encrypted communications. As such it has been identified as a priority by the European Commission. With several theoretical concepts...

Summary

Quantum Information Processing (QIP) is a groundbreaking new field with implications ranging from overcoming Moore\'s law to the security of encrypted communications. As such it has been identified as a priority by the European Commission. With several theoretical concepts having been clearly defined, and with quantum limits to Moore\'s law approaching, it is now important to find materials that will allow the physical implementations of qubits, the principal components for QIP. Molecular Nanomagnets (MNMs) are promising such materials which, however, exhibit short quantum decoherence times.
CHIRALQUBIT has focused on a new quantum property of MNMs, spin chirality, as a means to overcome this limitation and achieve decoherence-free qubits, with the added advantage of their rapid and precise electric manipulation. The project’s objectives were to confirm for the first time the electric control of spin-chiral coordination complexes, in particular antiferromagnetic triangles of half-integer spins, and study their relaxation and decoherence dynamics regarding transitions reversing their spin chiralities.
The project employed diverse methodologies from synthetic chemistry and spectroscopy to instrumentation and theory. Through the expertise it achieved the highly interdisciplinary training of an outstanding researcher in fields such as Electron Paramegnetic Resonance (EPR) spectroscopy and QIP, while also preparing him for an independent career through training in research management, mentoring, and proposal writing. Moreover, with its outreach actions it brought the general field closer to non-specialist and younger audiences. The unique combination of expertise of the host group and of the candidate and the highly innovative nature of the project, made this project a key opportunity for the advancement of the applicant\'s career as a mature researcher in the fields of Molecular Magnetism, EPR spectroscopy and QIP.
CHIRALQUBIT demonstrated the possibility to achieve elctric control of the magnetic properties of spin triangles, a conclusion which may encourage similar demonstrations in other types of molecular nanomagnets. This conclusion also bears implications to the spin-chiral encoding of information, which is based on electric-dipole induced transitions; with the magnetoelectic coupling clearly demonstrated, such transitions are expected to be observable as predicted by theory.

Work performed

The first task of CHIRALQUBIT was to undertake the detailed study of a series of spin triangles as a screening process for subsequent more detailed experiments with respect to their electric control. For this purpose, several spin triangles based on Fe(III)3, Cr(III)3, Cu(II)3 and V(IV) were either prepared for the first time, or were selected from the literature as promising candidates for electric spin control. In this latter case, their synthesis was either carried out in-house, or in collaboration with external synthetic groups.

Detailed characterizations of the spin Hamiltonian parameters of these spin triangles were conducted with multitechnique studies combining SQUID magnetometry and Electron Paramagnetic Resonance (EPR) spectroscopy. The experimental data were analyzed using detailed spin Hamiltonian models, employing detailed statistical treatment of the results. Common themes that emerged from these studies were: (i) the importance of Dzyaloshinskii-Moriya interactions in modulating the magnetic properties of those complexes and (ii) the quasi-ubiquity of distributions of the spin Hamiltonian parameters (strain effects), that need to be accounted for with a rigorous statistical treatment. These studies were reported in a series of articles, conference proceedings and lectures (see Publications I & 1 and Lectures).

Following up on those results, and based on its favourable characteristics, the ferric spin triangle [Fe3O(O2CPh)6(py)3](ClO4)·py was selected to test the theorized magnetoelectric coupling. In particular, oriented single crystals of this complex were studied using continuous-wave EPR spectroscopy, while being subjected to strong static electric fields. The experiments were carried out using custom-made sample holders developed during the course of the project. These experiments revealed that the spin of this triangle interacts with external electric fields, which consituted the first such demonstration for spin triangles. This study was reported in an peer-reviewed article and at a conference lecture (see Publications II and Lectures 4 & 5).


Publications I
4. Nitrite Reduction by Trinuclear Copper Pyrazolate Complexes: An Example of a Catalytic, Synthetic Polynuclear NO Releasing System
Inorg. Chem., 2019, 58, 7537 (DOI:10.1021/acs.inorgchem.9b00748)
3. “Determination of the distributions of the spin Hamiltonian parameters in spin triangles: a combined magnetic susceptometry and EPR spectroscopic study of the highly-symmetric [Cr3O(PhCOO)6(py)3](ClO4)·0.5py”
Inorg. Chem., 2018, 57, 13259 (DOI:10.1021/acs.inorgchem.8b01764)
2. “Interactions between H-bonded [CuII3(µ3-OH)] triangles; A combined magnetic susceptibility and EPR study”
Phys. Chem. Chem. Phys., 2018, 20, 17234 (DOI:10.1039/c8cp02643b)
1. “Towards ionic liquids with tailored magnetic properties: bmim+ salts of ferro- and antiferromagnetic CuII3 triangles”
Dalton Transactions, 2017, 46, 12263 (DOI:10.1039/c7dt02472j)

Publications II
“First Demonstration of Magnetoelectric Coupling in a Molecular Nanomagnet: Single-Crystal EPR studies of [Fe3O(O2CPh)6(py)3](ClO4)·py under static electric fields”
Chemistry, a European Journal, 2018, 24, 14896 (DOI:10.1002/chem.201803038)

Lectures:
1. Journées Scientifiques de l’Institut de Chimie de Strasbourg, Strasbourg, France, 2-3 November 2017
2. Matériaux 2018, Strasbourg Convention Centre, Strasbourg, France, 19-23 November 2018
3. Eighth North America-Greece-Cyprus Workshop on Paramagnetic Materials, Mystras, Greece, June 18-22, 2018
4. XVII International Feofilov Symposium on Spectroscopy of Crystals Doped with Rare Earth and Transition Metal Ions, Ekaternbourg, Russia, September 23-28, 2018
5. Department of Chemistry, University of Patras, Greece, October 26, 2018

Final results

\"CHIRALQUBIT proposed a radically new approach in qubit construction with MNMs, based on a quantum property called \"\"spin chirality\"\". This approach is expected to combine long decoherence times, convenient scalability, and practical electric control of the qubits bringing about unique advantages in their implementations. This combination of potential characteristics should constitute progress which goes significantly beyond the state of the art for qubit candidates.
CHIRALQUBIT demonstrated the previously predicted magnetoelectric couping in spin triangles, a first for polynuclear exchange-coupled systems. This discovery, viewed within the more general context of magnetoelectric and multiferroic materials, brings molecular nanomagnets within this very narrow class of materials of very high potential impact. Such materials are currently seeing a renaissance after their discovery in the 1960\'s, as they are considered in conjunction with novel applications, such as improved magnetic memory materials or functional elements for spintronic applications. Including molecular materials into this small but growing family, allows us to harness the immense potential provided by molecular chemistry.\"

Website & more info

More info: http://chiralqubit.eu.