Landau-Zener Transition in a Continuously Measured Single-Molecule Spin Transistor.

We monitor the Landau-Zener dynamics of a single-ion magnet inserted into a spin-transistor geometry. For increasing field-sweep rates, the spin reversal probability shows increasing deviations from that of a closed system. In the low-conductance limit, such deviations are shown to result from a dephasing process. In particular, the observed behaviors are successfully simulated by means of an adiabatic master equation, with time averaged dephasing (Lindblad) operators. The time average is tentatively interpreted in terms of the finite time resolution of the continuous measurement.

Magnetic properties and hyperfine interactions in Cr8, Cr7Cd, and Cr7Ni molecular rings from ¹9F-NMR.

A detailed experimental investigation of the (19)F nuclear magnetic resonance is made on single crystals of the homometallic Cr8 antiferromagnetic molecular ring and heterometallic Cr7Cd and Cr7Ni rings in the low temperature ground state. Since the F(-) ion is located midway between neighboring magnetic metal ions in the ring, the (19)F-NMR spectra yield information about the local electronic spin density and (19)F hyperfine interactions. In Cr8, where the ground state is a singlet with total spin S(T) = 0, the (19)F-NMR spectra at 1.7 K and low external magnetic field display a single narrow line, while when the magnetic field is increased towards the first level crossing field, satellite lines appear in the (19)F-NMR spectrum, indicating a progressive increase in the Boltzmann population of the first excited state S(T) = 1. In the heterometallic rings, Cr7Cd and Cr7Ni, whose ground state is magnetic with S(T) = 3/2 and S(T) = 1/2, respectively, the (19)F-NMR spectrum has a complicated structure which depends on the strength and orientation of the magnetic field, due to both isotropic and anisotropic transferred hyperfine interactions and classical dipolar interactions. From the (19)F-NMR spectra in single crystals we estimated the transferred hyperfine constants for both the F(-)-Ni(2+) and the F(-)-Cd(2+) bonds. The values of the hyperfine constants compare well to the ones known for F(-)-Ni(2+) in KNiF3 and NiF2 and for F(-)-Cr(3+) in K2NaCrF6. The results are discussed in terms of hybridization of the 2s, 2p orbitals of the F(-) ion and the d orbitals of the magnetic ion. Finally, we discuss the implications of our results for the electron-spin decoherence.

Quantum information processing with hybrid spin-photon qubit encoding.

We introduce a scheme to perform quantum information processing that is based on a hybrid spin-photon qubit encoding. The proposed qubits consist of spin ensembles coherently coupled to microwave photons in coplanar waveguide resonators. The quantum gates are performed solely by shifting the resonance frequencies of the resonators on a nanosecond time scale. An additional cavity containing a Cooper-pair box is exploited as an auxiliary degree of freedom to implement two-qubit gates. The generality of the scheme allows its potential implementation with a wide class of spin systems.

Molecular nanomagnets as quantum simulators.

Quantum simulators are controllable systems that can be used to simulate other quantum systems. Here we focus on the dynamics of a chain of molecular qubits with interposed antiferromagnetic dimers. We theoretically show that its dynamics can be controlled by means of uniform magnetic pulses and used to mimic the evolution of other quantum systems, including fermionic ones. We propose two proof-of-principle experiments based on the simulation of the Ising model in a transverse field and of the quantum tunneling of the magnetization in a spin-1 system.

Electrical control of the exciton-biexciton splitting in self-assembled InGaAs quantum dots.

The authors demonstrate how lateral electric fields can be used to precisely control the exciton-biexciton splitting in InGaAs quantum dots. By defining split-gate electrodes on the sample surface, optical studies show how the exciton transition can be tuned into resonance with the biexciton by exploiting the characteristically dissimilar DC Stark shifts. The results are compared to model calculations of the relative energies of the exciton and biexciton, demonstrating that the tuning can be traced to a dominance of hole-hole repulsion in the presence of a lateral field. Cascaded decay of the exciton-biexciton system enables the generation of entangled photon pairs without the need to suppress the fine structure splitting of the exciton. Our results demonstrate how the exciton-biexciton system can be electrically controlled.

Entanglement in supramolecular spin systems of two weakly coupled antiferromagnetic rings (purple-Cr7Ni).

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 entanglement in supramolecular structures.

Molecular spin clusters are mesoscopic systems whose structural and physical features can be tailored at the synthetic level. Besides, their quantum behavior is directly accessible in the laboratory and their magnetic properties can be rationalized in terms of microscopic spin models. Thus they represent an ideal playground within solid state systems to test concepts in quantum mechanics. One intriguing challenge is to control entanglement between molecular spins. Here we show how this goal can be pursued by discussing specific examples and referring to recent achievements.

Optimal generation of indistinguishable photons from non-identical artificial molecules.

We show theoretically that nearly indistinguishable photons can be generated with non-identical semiconductor-based sources. The use of virtual Raman transitions and the optimization of the external driving fields increases the tolerance to spectral inhomogeneity to the meV energy range. A trade-off emerges between photon indistinguishability and efficiency in the photon-generation process. Linear (quadratic) dependence of the coincidence probability within the Hong-Ou-Mandel setup is found with respect to the dephasing (relaxation) rate in the semiconductor sources.

Spin-communication channels between Ln(III) bis-phthalocyanines molecular nanomagnets and a magnetic substrate.

Learning the art of exploiting the interplay between different units at the atomic scale is a fundamental step in the realization of functional nano-architectures and interfaces. In this context, understanding and controlling the magnetic coupling between molecular centers and their environment is still a challenging task. Here we present a combined experimental-theoretical work on the prototypical case of the bis(phthalocyaninato)-lanthanide(III) (LnPc2) molecular nanomagnets magnetically coupled to a Ni substrate. By means of X-ray magnetic circular dichroism we show how the coupling strength can be tuned by changing the Ln ion. The microscopic parameters of the system are determined by ab-initio calculations and then used in a spin Hamiltonian approach to interpret the experimental data. By this combined approach we identify the features of the spin communication channel: the spin path is first realized by the mediation of the external (5d) electrons of the Ln ion, keeping the characteristic features of the inner 4 f orbitals unaffected, then through the organic ligand, acting as a bridge to the external world.

The TRADE experiment: shielding calculations for the building hosting the subcritical system.

The TRADE project (TRiga Accelerator Driven Experiment), to be performed at the existing TRIGA reactor at ENEA Casaccia, has been proposed as a validation of the accelerator-driven system (ADS) concept. TRADE will be the first experiment in which the three main components of an ADS--the accelerator, spallation target and sub-critical blanket--are coupled at a power level sufficient to encounter reactivity feedback effects. As such, TRADE represents the necessary intermediate step in the development of hybrid transmutation systems, its expected outcomes being considered crucial--in terms of proof of stability of operation, dynamic behaviour and licensing issues--for the subsequent realisation of an ADS Transmutation Demonstrator. An essential role in the feasibility study of the experiment is played by radioprotection calculations. Such a system exhibits new characteristics with respect to a traditional reactor, owing to the presence of the proton accelerator. As beam losses always occur under normal operating conditions of an accelerator, shielding studies need to be performed not only around the reactor but also along the beam line from the accelerator to the spallation target. This paper illustrates a preliminary evaluation, using Monte Carlo methods, of the additional shielding to be located around the reactor structures, the beam transport line and the existing reactor building to allow access into the reactor hall and to restrict the doses outside to their legal limits.

[Angiomatoid malignant fibrous histiocytoma. Clinico-pathologic and immunohistochemical study of a case]. / Istiocitoma fibroso maligno angiomatoide. Studio clinico-patologico ed immunoistochimico di un caso.

The results of a clinico-pathologic and immunohistochemical study of an angiomatoid malignant fibrous histiocytoma are reported. This lesion is an uncommon tumor of the superficial soft tissue, of low-grade malignancy, typical of adolescence and early adult life. The patient, a 10-year-old female, presented with a mass of the left popliteal fossa, treated with surgical excision of the tumor and the surrounding cutaneous and subcutaneous tissue. The tumor was a well-circumscribed, firm nodule measuring 2.5 x 1.0 cm. Histologically, it showed aggregates of spindled and rounded cells often lining cystic cavities filled with blood. The immunohistochemical analysis revealed a cytoplasmatic immunoreactivity for KP1 (CD68), which was taken as indicating that the tumoral mesenchymal cells had acquired phagocytic capacities. The patient is well without signs of local recurrence or metastatic disease 4 years after the surgical treatment. The case reported confirms that appropriate local surgery is the elective therapy for this type of soft tissue tumor.

[Adenomyomatosis of the gallbladder: the authors' personal experience]. / Adenomiomatosi della colecisti: esperienza personale.

The authors report on a particular affection of the cholecyst wall known as adenomyomatosis. Having observed seven cases in the last three years they analyse the most suitable diagnostic methods and treatment.

[Extra-abdominal fibromatosis (extra-abdominal desmoid): case report]. / Fibromatosi extraaddominale (desmoide extraaddominale): contributo casistico.

The extra-abdominal fibromatosis is a benign tumour presenting considerable problems in terms of diagnosis and therapy. The Authors report a case recently observed.

[Mondor's disease: our experience]. / Malattia di Mondor: la nostra esperienza.

Mondor's disease is commonly described as thrombophlebitis of the subcutaneous veins of the chest. It is a relatively uncommon syndrome, generally considered of trivial importance for its poor symptoms: local pain, rarely fever. Recovery is obtained in one or two months with adequate medical treatment. Common causes are traumas, surgery, stress, breast phlogosis; however, some Authors still consider the syndrome as a sinchronous breast cancer "marker".

[Pulmonary hamartoma: a case report]. / L'amartoma polmonare: contributo casistico.

The authors describe a case of lung hamartoma recently observed. Diagnosis occurred by chance through routine chest X-rays. A stationary radiological aspect of the hamartoma, regularly followed up, suggested to defer surgery up to the moment of a visible radiologic enlargement of the lesion.

[Primary infarction of the greater omentum: our experience in 3 cases]. / Infarto primitivo del grande omento: nostra esperienza su tre casi.

The infarction of the greater omentum is an unusual cause of acute abdominal pain. The Authors report their experience in the management of three cases. It is stressed that clinical manifestations are those of an appendicitis or cholecystitis; therefore, the diagnosis is usually intraoperative.

[Superselective monolateral subarachnoid anesthesia in saphenectomy by long stripping]. / L'anestesia subaracnoidea monolaterale superselettiva nella safenectomia per stripping lungo.

The authors describe a recent anaesthetic technique: the subarachnoid monolateral superselective anaesthesia. Currently they use it in the surgical operation of "long stripping" saphenectomy. They argue on the utility of codifying this technique for its numberless advantages and discuss on the opportunity to perform day-hospital saphenectomy.

[A 3-year experience of the repair of voluminous abdominal laparoceles with patches of prosthetic material]. / Un'esperienza di tre anni nella riparazione dei voluminosi laparoceli addominali con pezze di materiale protesico.

The authors deal with huge ventral hernias having a defect of more than 10 cm in diameter. They report 16 cases in three years of experience: 10 treated with Marlex patches and 6 treated with Goretex prosthetic material.