N.C.S.R. "Demokritos"


Department of Materials Science

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Pulsed EPR and Quantum Computing

This project involves the implementation of advanced pulsed EPR methods and the development of new materials for quantum information processing (QIP). The field of QIP based on EPR has received increased attention in our days with the main effort being the construction of fast and reliable two-qubit (quantum bit) quantum gates based exclusively on electron spins with controllable exchange interactions. This is however a challenging task, especially when crystalline materials of this kind are on demand. This difficulty has motivated an on-going effort to find appropriate electron spin qubits, including for instance quantum dots, single-molecule magnets, and antiferromagnetic heterometallic rings or metal clusters. Recently we showed how pulse EPR spectroscopy can give insight into the electronic structure of molecular magnets and probe their potential use as qubits for quantum information processing. The system under study was the trinuclear oxo-centered iron(III) complex, [Fe33-O)(O2CPh)5(salox)(EtOH)(H2O)] (salox2- is the dianion of salicylaldehyde oxime), where the three FeIII (S = 5/2) sites are antiferromagnetically coupled to give an S = 1/2 ground state. The temperature dependence of the spin-lattice relaxation time T1 between 4.5 and 11 K revealed that the two-level Orbach relaxation process is dominant with the first excited state lying 57 cm-1 above the ground state. In addition, two-pulse electron spin echo experiments showed that the dephasing times are of the order of 2.6 μs and exhibit weak temperature dependence. Finally, the coherent manipulation of the electron spins was examined for the first time for molecular magnets by means of transient nutation experiments (Rabi oscillations) which are equivalent to the one-qubit NOT quantum gate.

Department of Materials Science, N.C.S.R. "Demokritos", 153 10 Aghia Paraskevi, Attiki, phone: +30 210 6503381, fax: +30 210 6519430
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