Flopping-mode electric dipole spin resonance

Traditional approaches to controlling single spins in quantum dots require the generation of large electromagnetic fields to drive many Rabi oscillations within the spin coherence time. We demonstrate "flopping-mode" electric dipole spin resonance, where an electron is electrically driven in a Si/SiGe double quantum dot in the presence of a large magnetic field gradient. At zero detuning, charge delocalization across the double quantum dot enhances coupling to the drive field and enables low power electric dipole spin resonance. Through dispersive measurements of the single electron spin state, we demonstrate a nearly three order of magnitude improvement in driving efficiency using flopping-mode resonance, which should facilitate low power spin control in quantum dot arrays

Controlled MOCVD growth of Bi2Se3 topological insulator nanoribbons

Topological insulators are a new class of materials that support topologically protected electronic surface states. Potential applications of the surface states in low dissipation electronic devices have motivated efforts to create nanoscale samples with large surface-to-volume ratios and highly controlled stoichiometry. Se vacancies in Bi2Se3 give rise to bulk conduction, which masks the transport properties of the surface states. We have therefore developed a new route for the synthesis of topological insulator nanostructures using metalorganic chemical vapour deposition (MOCVD). MOCVD allows for control of the Se/Bi flux ratio during growth. With the aim of rational growth, we vary the Se/Bi flux ratio, growth time, and substrate temperature, and observe morphological changes which indicate a growth regime in which nanoribbon formation is limited by the Bi precursor mass-flow. MOCVD growth of Bi2Se3 nanostructures occurs via a distinct growth mechanism that is nucleated by gold nanoparticles at the base of the nanowire. By tuning the reaction conditions, we obtain either single-crystalline ribbons up to 10 microns long or thin micron-sized platelets.Comment: Related papers at http://pettagroup.princeton.ed

Landau-Zener-Stuckelberg Interferometry of a Single Electron Charge Qubit

We perform Landau-Zener-Stuckelberg interferometry on a single electron GaAs charge qubit by repeatedly driving the system through an avoided crossing. We observe coherent destruction of tunneling, where periodic driving with specific amplitudes inhibits current flow. We probe the quantum dot occupation using a charge sensor, observing oscillations in the qubit population resulting from the microwave driving. At a frequency of 9 GHz we observe excitation processes driven by the absorption of up to 17 photons. Simulations of the qubit occupancy are in good agreement with the experimental data.Comment: Related papers at http://pettagroup.princeton.ed

Entanglement between static and flying qubits in quantum wires

A weakly bound electron in a semiconductor quantum wire is shown to become entangled with an itinerant electron via the coulomb interaction. The degree of entanglement and its variation with energy of the injected electron, may be tuned by choice of spin and initial momentum. Full entanglement is achieved close to energies where there are spin-dependent resonances. Possible realisations of related device structures are discussed

The burden of hepatocellular carcinoma in non-alcoholic fatty liver disease: Screening issue and future perspectives

In recent decades, non-alcoholic fatty liver disease (NAFLD) has become the most common liver disease in the Western world, and the occurrence of its complications, such as hepatocellular carcinoma (HCC), has rapidly increased. Obesity and diabetes are considered not only the main triggers for the development of the disease, but also two independent risk factors for HCC. Single nucleotide polymorphisms (such as PNPLA3, TM6SF2 and MBOAT7) are related to the susceptibility to the development of HCC and its progression. Therefore, an appropriate follow-up of these patients is needed for the early diagnosis and treatment of HCC. To date, international guidelines recommend the use of ultrasonography with or without alpha-fetoprotein (AFP) in patients with advanced fibrosis. Furthermore, the use of non-invasive tools could represent a strategy to implement surveillance performance. In this review, we analyzed the main risk factors of NAFLD-related HCC, the validated screening methods and the future perspectives

Pharmacological therapy of non-alcoholic fatty liver disease: What drugs are available now and future perspectives

The non-alcoholic fatty liver disease (NAFLD) is rapidly becoming the most common cause of chronic liver disease as well as the first cause of liver transplantation. NAFLD is commonly associated with metabolic syndrome (MetS), and this is the most important reason why it is extremely difficult to treat this disease bearing in mind the enormous amount of interrelationships between the liver and other systems in maintaining the metabolic health. The treatment of NAFLD is a key point to prevent NASH progression to advanced fibrosis, to prevent cirrhosis and to prevent the development of its hepatic complications (such as liver decompensation and HCC) and even extrahepatic one. A part of the well-known healthy effect of diet and physical exercise in this setting it is important to design the correct pharmaceutical strategy in order to antagonize the progression of the disease. In this regard, the current review has the scope to give a panoramic view on the possible pharmacological treatment strategy in NAFLD patients