Portraying entanglement between molecular qubits with four-dimensional inelastic neutron scattering

E Garlatti,S Carretta,T Guidi,G F S Whitehead,J Ollivier,H Mutka,G Amoretti,G Timco,I J Vitorica-Yrezabal,S Ansbro,P Santini,R E P Winpenny

doi:10.1038/ncomms14543

E Garlatti, S Carretta + Show 10 more

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https://doi.org/10.1038/ncomms14543

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Entanglement is a crucial resource for quantum information processing and its detection and quantification is of paramount importance in many areas of current research. Weakly coupled molecular nanomagnets provide an ideal test bed for investigating entanglement between complex spin systems. However, entanglement in these systems has only been experimentally demonstrated rather indirectly by macroscopic techniques or by fitting trial model Hamiltonians to experimental data. Here we show that four-dimensional inelastic neutron scattering enables us to portray entanglement in weakly coupled molecular qubits and to quantify it. We exploit a prototype (Cr7Ni)2 supramolecular dimer as a benchmark to demonstrate the potential of this approach, which allows one to extract the concurrence in eigenstates of a dimer of molecular qubits without diagonalizing its full Hamiltonian.

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Entanglement is a crucial resource for quantum information processing and its detection and quantification is of paramount importance in many areas of current research
A large number of supramolecular complexes of molecular nanomagnets are being synthesized, but so far entanglement between molecular subunits has only been experimentally demonstrated by exploiting susceptibility as a witness in a (Cr7Ni)[2] dimer or by fitting trial model Hamiltonians to electron paramagnetic resonance data[23]
The Cr7Ni subunits have been fully characterized by INS and electron paramagnetic resonance spectroscopies and by low-temperature specific heat and magnetometry measurements[26]

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Entanglement is a crucial resource for quantum information processing and its detection and quantification is of paramount importance in many areas of current research. Coupled molecular nanomagnets provide an ideal test bed for investigating entanglement between complex spin systems. Entanglement in these systems has only been experimentally demonstrated rather indirectly by macroscopic techniques or by fitting trial model Hamiltonians to experimental data. Arrays of weakly coupled molecular nanomagnets represent an ideal playground for investigating quantum entanglement between complex spin systems[4,20]. A large number of supramolecular complexes of molecular nanomagnets are being synthesized, but so far entanglement between molecular subunits has only been experimentally demonstrated by exploiting susceptibility as a witness in a (Cr7Ni)[2] dimer or by fitting trial model Hamiltonians to electron paramagnetic resonance data[23]. The crosssection directly reflects dynamical correlations between individual atomic spins in the molecule, and distinguishes between intra-ring correlations, associated with the composite nature of the molecular qubits, and inter-ring spin–spin correlations, which are a signature of entanglement between qubits

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