RESEARCH

My research activity has been mainly focused on mesoscopic and molecular systems of interest for the implementation of quantum devices, namely semiconductor quantum dots (QDs) and molecular magnets (MMs). n particular, I've worked at the modelization of such systems; at the elaboration of schemes for their coherent manipulation and for the implementation of quantum logical gates; and at the simulation of their dynamics, with the inclusion of the relevant decoherence processes.

SEMICONDUCTOR QUANTUM DOTS (QDs)
• Modelization. Numerical calculation of the carrier confined states, including the effect of external (electric and magnetic) fields and of coherent interdot coupling, within the effective-mass approximation. Calculation of the corresponding few-particle states, by means of a configuration- interaction technique. Optical properties associated with transition between such states, and their dependence on possible charging effects. Tuning of the interdot coupling, and of the resulting interdot correlations, through the application of external fields.
• Coherent manipulation and decoherence processes. Schemes for the coherent optical manipulation (based on stimulated Raman adiabatic passage) of a charged carrier in coupled QDs. Relaxation in coupled QDs related to phonon emission, and its suppression by means of electric and magnetic fields.
• Encoding and manipulation of quantum information. Proposal based on the qubit encoding in the excitonic degrees of freedom, and on their manipulation through sequences of ultrafast laser pulses. Proposal based on the qubit identification with the electronic spin, and on its all-optical manipulation by means of stimulated Raman transitions.

QUANTUM DOTS IN OPTICAL MICROCAVITIES (MCs)
• Sources of non-classical light. QD-MC systems as sources of single photons on demand: limitations to the photon indistinguishability arising from the decoerence processes and from the incoherent nature of the pumping. Simulation, within the density-matrix formalism, of quantum tomography experiments, and calculation of the corresponding concurrence in photon pairs generated by QD cascade emission.
• Single spin read-out. Proposal and simulation of optical (quantum non-demolition) measurement for a single carrier spin in a QD-MC system. The scheme relies on the controlled entanglement between the spin state and the polarization of cavity photons.

MOLECULAR MAGNETS (MM):
• Encoding and manipulation of quantum information. Qubit encoding in antiferromagnetic MMs (namely, heterometallic rings and triangles), and molecule modelling through spin Hamiltonians. Schemes for the implementation of (one- and two-qubit) quantum gates, in the absence of local fields and of tuneable intermolecular couplings.
• Decoherence. Loss of phase coherence in heterometallic MMs as a consequence of the hyperfine interactions between the magnetic ions and the nuclear environment. Electron-nuclear reversibility by spin-echo sequences.
• Electric spin control. Pulsed electric fields as an alternative route to electron spin manipulation in antiferromagnetic molecular magnets.

LIST OF PUBLICATIONS

MAIN SCIENTIFIC PUBLICATIONS

1. M. Trif, F. Troiani, D. Stepanenko, and D. Loss, "Spin-electric coupling in molecular magnets", Phys. Rev. Lett., 101, 217201 (2008).
2. G. A. Timco, S. Carretta, F. Troiani, F. Tuna, R. J. Pritchard, E. J. L. McInnes, A. Ghirri, A. Candini, P Santini, G. Amoretti, M. Affronte and R. E. P. Winpenny, "Engineering coupling between molecular spin qubits by supramolecular chemistry", Nature Nanotech. 4, 173 (2009).
3. M. Abbarchi, F. Troiani, C. Mastrandrea, G. Goldoni, T. Kuroda, T. Mano, K. Sakoda, N. Koguchi, S. Sanguinetti, A. Vinattieri, and M. Gurioli, "Sprectral diffusion and line broadening in single self-assembled GaAs/AlGaAs quantum dot photoluminescence", Appl. Phys. Lett. 93, 162101 (2008).
4. S. Shojaei, F. Troiani, A. Asgari, M. Kalafi, G. Goldoni "Coulomb-induced non-linearities in GaN microdisks" The European Phys. J. B 65, 505 (2008).
5. E. Cancellieri, F. Troiani, and G. Goldoni, "Indistinguishable photons from different quantum dots: an optimization approach based on evolutionary programming", submitted (2008).
6. F. Troiani and C. Tejedor, "Entangled photon pairs from a quantum dot cascade decay: the effect of time reordering", Phys. Rev. B 78, 155305 (2008).
7. D. M. Tomecka, V. Bellini, F. Troiani, F. Manghi, G. Kamieniarz, and M. Affronte, "Ab initio study on a chain model of the Cr8 molecular magnet", Phys. Rev. B 77, 224401 (2008).
8. F. Troiani, V. Bellini, and M. Affronte, "Electron-spin decoherence in antiferromagnetic molecular rings: the effect of hyperfine interactions", Phys. Rev. B 77, 054428 (2008).
9. E. del Valle, F. P. Laussy, F. Troiani, and C. Tejedor, "Entanglement and lasing with two quantum dots in a microcavity", Phys. Rev. B 76, 235317 (2007).
10. S. Carretta, P. Santini, G. Amoretti, F. Troiani, M. Affronte, "Spin triangles as optimal units for molecule-based quantum gates", Phys. Rev. B 76, 24408 (2007).
11. J. I. Perea, F. Troiani, and C. Tejedor, "Correlated photon-pair emission from pulse-pumped quantum dots embedded in a microcavity", Solid State Commun. 144, 542 (2007).
12. F. Troiani, I. Wilson-Rae, and C. Tejedor, "All-optical non-demolition measurement of single-hole spin in a quantum-dot molecule", Appl. Phys. Lett. 90, 144103 (2007).
13. A. Bertoni, M. Rontani, G. Goldoni, F. Troiani, E. Molinari, Response to "Comment on `Field-controlled suppression of phonon-induced transitions in coupled quantum dots' [Appl. Phys. Lett. 88, 4729 (2006)]", Appl. Phys. Lett. 88, 196102 (2006).
14. F. Troiani, J. I. Perea, and C. Tejedor, "Cavity-assisted generation of entangled photon pairs by a quantum-dot cascade decay", Phys. Rev. B 74, 235310 (2006).
15. U. Hohenester, J. Fabian, and F. Troiani, "Adiabatic Passage Schemes in Coupled Semiconductor Nanostructures", Optics Communications 264, 426 (2006).
16. F. Troiani, J. I. Perea, and C. Tejedor, "Analysis of the photon indistinguishability in incoherently excited quantum dots", Phys. Rev. B 73, 35316 (2006).
17. F. Troiani, M. Affronte, S. Carretta, P. Santini, and G. Amoretti, "Proposal for quantum gates in permanently coupled antiferromagnetic spin rings without need of local fields", Phys. Rev. Lett. 94, 190501 (2005).
18. F. Troiani, A. Ghirri, M. Affronte, S. Carretta, P. Santini, G. Amoretti, S. Piligkos, G. Timco, and rue> R. E. P. Winpenny, "Molecular engineering of antiferromagnetic molecular rings for quantum computation", Phys. Rev. Lett. 94, 207208 (2005).
19. D. Bellucci, F. Troiani, G. Goldoni, and E. Molinari, "Neutral and charged electron-hole complexes in artificial molecules: Quantum transitions induced by the in-plane magnetic field", Phys. Rev. B 70, 205332 (2004).
20. A. Bertoni, M. Rontani, G. Goldoni, F. Troiani, and E. Molinari, "Field-controlled suppression of phonon-induced transitions in coupled quantum dots", Appl. Phys. Lett. 85, 4729 (2004).
21. D. Bellucci, M. Rontani, F. Troiani, G. Goldoni, and E. Molinari, "Competing mechanisms for singlet-triplet transition in artificial molecules", Phys. Rev. B 69, RC 201308 (2004).
22. F. Troiani, "Tunneling and Electric-Field Effects on Electron-Hole Localization in Artificial Molecules", Solid State Comm. 128, 147 (2003).
23. F. Troiani, E. Molinari, and U. Hohenester, "High-finesse optical quantum gates for electron spins in artificial molecules", Phys.
24. M. Lomascolo, A.Vergine, T.K. Johal, R. Rinaldi, A. Passaseo, R. Cingolani, S. Patanč, M. Lombardi, M. Allegrini, F. Troiani, and E. Molinari, "Dominance of charged excitons in single quantum dot photoluminescence spectra", Phys. Rev. B 66, RC 41302 (2002).
25. F. Troiani, U. Hohenester, and E. Molinari, "Electron-hole localization in coupled quantum dots", Phys. Rev. B 65, RC 161301 (2002).
26. M. Rontani, F. Troiani, U. Hohenester, and E. Molinari, "Quantum phases in artificial molecules", Solid State Commun. 119, 309 (2001) Invited paper in Special Issue on Spin Effects in Mesoscopic Systems.
27. U. Hohenester, F. Troiani, E. Molinari, G. Panzarini, and C. Machiavello, "Coherent population transfer in coupled semiconductor quantum dots", Appl. Phys. Lett. 77, 1864 (2000).
28. F. Troiani, U. Hohenester, and E. Molinari, "Exploiting exciton-exciton interactions in semiconductor quantum dot for quantum-information processing", Phys. Rev. B 62, RC 2263 (2000).

REVIEW ARTICLES AND BOOK CHAPTERS

1. F. Troiani, I. Wilson-Rae, and C. Tejedor, "Optical read-out of single-carrier spin in semiconductor quantum dots", in Semiconductor Quantum Bits, edito da Pan Stanford Publishing / World Scientific Publishing (2007), in press.
2. F. Troiani, U. Hohenester, E. Molinari, I. D'Amico, and F. Rossi, "Few-particle effects in semiconductor macroatoms/molecules" (Ch. 5), in Semiconductor macroatoms: basic physics and quantum-device applications, edited by Imperial College Press / World Scientific Publishing (2006).
3. I. D'Amico, and F. Rossi, F. Troiani, U. Hohenester, "All-optical schemes for quantum-information processing with semiconductor macroatoms" (Ch. 8), in Semiconductor macroatoms: basic physics and quantum-device applications, edited by Imperial College Press / World Scientific Publishing (2006).
4. U. Hohenester, F. Troiani, and E. Molinari, "Optically induced coherence effects in artificial atoms and molecules", in Radiation-Matter Interaction in Confined Systems, edited by L.C. Andreani, G. Benedek, and E. Molinari (Italian Physics Society, Bologna, 2002), p. 25.

OTHER PUBLICATIONS ON REFEREED JOURNALS

1. E. del Valle, F. Laussy, F. Troiani, and C. Tejedor , "Steady state of two quantum dots in a cavity", Superlattices and Microstructures, in press.
2. E. del Valle, F. Troiani, and C. Tejedor, "Cavity electrodynamics with two quantum dots", Proc. 28th International Conference on the Physics of Semiconductors (Vienna, 2006), in press.
3. M. Affronte, F. Troiani, A. Ghirri, A. Candini, M. Evangelisti, V. Corradini, S. Carretta, P. Santini, G. Amoretti, F. Tuna, G. Timco and R. E. P. Winpenny, "Single molecule magnets for quantum computation", J. Phys. D: Appl. Phys., in press.
4. M. Affronte, F. Troiani, A. Ghirri, A. Candini, M. Evangelisti, V. Corradini, S. Carretta, P. Santini, G. Timco , R.E.P. Winpenny, "Molecular Spin Clusters for Quantum Computation", J. Magnetism & Magnetic Materials 310, 1460-1461 (2007).
5. M. Affronte, F. Troiani, A. Ghirri, A. Candini, M. Evangelisti, S. Carretta, P. Santini, G. Amoretti, S. Piligkos, G. Timco and R. E. P. Winpenny, "Antiferromagnetic molecular rings for quantum computation", Polyhedron 24 2562 (2005).
6. D. Bellucci, F. Troiani, G. Goldoni, and E. Molinari, "Magnetic-field dependent optical properties and interdot correlations in artificial molecules", J. Lumin. 112, 109 (2005).
7. D. Bellucci, F. Troiani, G. Goldoni, and E. Molinari "Biexcitons in artificial molecules with in-plane magnetic field", Physica E 26, 308 (2005).
8. D. Bellucci, M. Rontani, G. Goldoni, F. Troiani, and E. Molinari "Interacting electrons in artificial molecules with magnetic field of arbitrary direction", Physica E 26, 327 (2005).
9. A. Bertoni, M. Rontani, G. Goldoni, F. Troiani, E. Molinari, "Suppression of acustic-phonon-induced electron transitions in coupled quantum dots", Physica E 26, 427 (2005).
10. G. Goldoni, F. Troiani, M. Rontani, D. Bellucci, E. Molinari, and U. Hohenester, "Collective properties of electrons and holes in coupled quantum dots", Proc. NATO Series II 190, edito da B. Joyce, P. Kelires, A. Naumovets, and D.D. Vvedensky (2005).
11. F. Troiani, U. Hohenester, and E. Molinari, "High-finesse optical quantum gates for electron spins in artificial molecules", Physica E 21, 1061 (2004).
12. D. Bellucci, M. Rontani, G. Goldoni, F. Troiani, and E. Molinari, "Spin-Spin Interaction In Artificial Molecules With In-Plane Magnetic Field", to appear in Physica E (2004).
13. U. Hohenester, F. Troiani, and E. Molinari, "Few-particle states and quantum-information processing in quantum dots", Proc. 25th International Conference on the Physics of Semiconductors (Osaka 2000), edited by N. Miura and T. Ando, Springer Berlin (2001).
14. F. Troiani, U. Hohenester, and E. Molinari, "Quantum-information processing in semiconductor quantum dots", phys. stat. sol. (b) 224, 849 (2001)