Entanglement in Supramolecular Spin Systems of Two Weakly Coupled Antiferromagnetic Rings (Purple-Cr7Ni)

Abstract

We characterize supramolecular magnetic structures, consisting of two weakly coupled antiferromagnetic rings, by low-temperature specific heat, susceptibility, magnetization and electron paramagnetic resonance measurements. Intra- and inter-ring interactions are modeled through a microscopic spin-Hamiltonian approach that reproduces all the experimental data quantitatively and legitimates the use of an effective two-qubit picture. Spin entanglement between the rings is experimentally demonstrated through magnetic susceptibility below 50 mK and theoretically quantified by the concurrence.

Spin dynamics of molecular nanomagnets unravelled at atomic scale by four-dimensional inelastic neutron scattering

“…The possibility to extract all two-spin dynamical correlation functions opens remarkable perspectives in the understanding of crucial but elusive quantum phenomena in several classes of magnetic molecules. In particular, supramolecular complexes containing linked molecular nanomagnets have been demonstrated to display entanglement [12,13] and to be excellent candidates for implementing quantumcomputation [8] and quantum-simulation algorithms [9]. The present method could be applied to reach a profound knowledge of the structure of the eigenstates of these complexes and of the entanglement between different molecular qubits.…”

“…It is one of the most studied MNMs both for its intrinsic interest and for being the precursor of a large family of heterometallic molecules and supramolecular complexes which are intensively studied for a number of fundamental and applicative issues [8,12,13,[26][27][28]. The spin-Hamiltonian of Cr 8 contains a dominating nearest-neighbor Heisenberg AF exchange and small axial anisotropic terms:…”

“…Shells of organic ligands provide magnetic separation between adjacent magnetic cores, which behave as identical and independent zero-dimensional units [1]. The magnetic dynamics are characterized by strong quantum fluctuations and this makes MNMs of great interest in quantum magnetism as model systems to investigate a range of phenomena, such as quantum-tunnelling of the magnetization [2][3][4], Néel-vector tunnelling (NVT) [5,6], quantum information processing [7][8][9], quantum entanglement [10][11][12][13] or decoherence [14][15][16]. Besides their fundamental interest, MNMs are also the focus of intense research for the potential technological applications as classical or quantum bits [1,[7][8][9]17] and as magnetocaloric refrigerants [18].…”

Molecular Spins in the Context of Quantum Technologies

“…Spin entanglement can be obtained within a single molecule or at supramolecular level (i.e., between molecules) by controlling spin topology and magnetic interactions. Along this line, dimers of molecular spins with weak permanent magnetic coupling could be designed and synthesized [25] and sizable spin entanglement was demonstrated [26]. One issue of this approach is related to the fact that, during the gate operation, the coupling between the two qubits needs to be switched on and off in order to allow independent rotation of the two spin qubits.…”

Relaxation dynamics in a Fe7nanomagnet

“…7,8 In addition, MNMs exhibit a wide range of intriguing quantum phenomena, such as quantum tunneling of the magnetization, [9][10][11] decoherence, 12,13 or quantum entanglement between distinct cores. [14][15][16][17] MNMs also present great advantages from the standpoint of theoretical modeling. Indeed, it has been demonstrated that the effective spin Hamiltonian is a powerful model to describe magnetic properties of these clusters.…”