The control of quantum correlations in solid state systems by means of material engineering is a broad avenue to be explored, since it makes possible steps toward the limits of quantum mechanics and the design of novel materials with applications on emerging quantum technologies. In this context, this Letter explores the potential of molecular magnets to be prototypes of materials for quantum information technology. More precisely, we engineered a material and from its geometric quantum discord we found significant quantum correlations up to 9540 K (even without entanglement); and, in addition, a pure singlet state occupied up to around 80 K (above liquid nitrogen temperature). These results could only be achieved due to the carboxylate group promoting a metal-to-metal huge magnetic interaction. Keywords: Quantum discord, Geometric correlations, Molecular magnetsQuantum entanglement has received a considerable attention as a remarkable resource for quantum information processing [1][2][3]. In spite of that, it is fragile and can easily vanish due to the inevitable interaction of the system with its environment [4]; and due to this condition, it was thought that entanglement could only exist at low temperatures. However, recently, it has been shown that entanglement can also exist at higher temperatures, and can be detected through the measurement of some thermodynamic observables [5][6][7][8][9][10][11][12][13][14][15][16][17].Nevertheless, quantum entanglement does not encompass all quantum correlations in a system and recent studies have greatly expanded the notion of quantum correlations [18][19][20][21][22][23][24][25][26][27][28][29]; and the measure of quantum excess of correlations has been named as quantum discord [19][20][21]. In the last years, it was understood that quantum discord has an important role in many quantum information processing even without entanglement. Notably, this quantity can also detect quantum phase transitions [25,30,31].Despite much effort by the scientific community, there are only a few results on the analytical expression of quantum discord; and only for a certain class of states an exact solution is known [23-27, 32, 33]. This fact stimulated alternative measurements of quantum discord, theoretically and experimentally [22,24,29,[34][35][36]. The recent demonstration that quantum discord can be measured by the thermodynamic properties of solids, such as magnetic susceptibility, internal energy [35][36][37], specific heat [35,36] and even neutron scattering data [22], shows that quantum correlations can be related to significant macroscopic effects allowing the measurement and the control of quantum correlations in solid state systems by means of material engineering. Thus, the design of novel materials becomes an actual challenge to overcome.In this direction, molecular magnets can be an excellent opportunity to achieve this goal as prototypes of materials for quantum information technology. They combine classical properties, found in any macroscopic magnet, with quantum one...

The study of quantum correlations in solid state systems is a large avenue for research and their detection and manipulation are an actual challenge to overcome. In this context, we show by using first-principles calculations on the prototype material KNaCuSi4O10 that the degree of quantum correlations in this spin cluster system can be managed by external hydrostatic pressure. Our results open the doors for research in detection and manipulation of quantum correlations in magnetic systems with promising applications in quantum information science.

In this work we report an application of coherence theory to a low-dimensional molecular magnetic system, through the study of temperature, pressure and magnetic fields influence on the quantum coherence of a Cu(II) metal-silicate framework as a function of the magnetic susceptibility of the compound. Our results show that the quantum coherence of a low-dimensional molecular magnetic system can be handled by the management of the external conditions, offering an alternative way to identify quantum coherence through magnetometric experiments.

The study of advanced quantum devices for energy storage has attracted the attention of the scientific community in the past few years. Although several theoretical progresses have been achieved recently, experimental proposals of platforms operating as quantum batteries under ambient conditions are still lacking. In this context, this work presents a feasible realization of a quantum battery in a carboxylate-based metal complex, which can store a finite amount of extractable work under the form of quantum discord at room temperature, and recharge by thermalization with a reservoir. Moreover, the stored work can be evaluated through non-destructive measurements of the compound’s magnetic susceptibility. These results pave the way for the development of enhanced energy storage platforms through material engineering.

The syntheses, crystal structures, and magnetic properties of two new copper(II) complexes with molecular formulas [Cu 7 (μ 2 -OH 2 ) 6 (μ 3 -O) 6 (adenine) 6 ](NO 3 ) 2 ·6H 2 O (1) and [Cu 2 (μ 2 -H 2 O) 2 (adenine) 2 (H 2 O) 4 ](NO 3 ) 4 ·2H 2 O (2) are reported. The heptanuclear compound is composed of a central octahedral CuO 6 core sharing edges with six adjacent copper octahedra. In 2, the copper octahedra shares one equatorial edge. In both compounds, these basic copper cluster units are further linked by water bridges and bridging adenine ligands through N3 and N9 donors. All copper(II) centers exhibit Jahn-Teller distorted octahedral coordination characteristic of a d 9 center. The study of the magnetic properties of the heptacopper complex revealed a dominant ferromagnetic intra-cluster interaction, while the dicopper complex exhibits antiferromagnetic intra-dimer interactions with weakly ferromagnetic inter-dimer interaction.