D. QUANTUM METROLOGY
1. Quantum Hall as resistance standards.
Contact person:
Stefan Heun
Stefano Roddaro
Graphene devices are expected to display observable quantization at larger electronic temperatures, thanks to the large Landau level spacing they display. Strain engineering will be explored as a method to achieve Landau level quantization in the absence of a large magnetic field, exploiting pseudo-magnetic fields that are known to occur in deformed two-dimensional lattices with a honeycomb symmetry.
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Landau fan diagram: more than 12 Landau levels can be seen in this diagram. The longitudinal resistance across the split gate is plotted as a function of back gate voltage and magnetic field.
S. Xiang, V. Miseikis, L. Planat, S. Guiducci, S. Roddaro, C. Coletti, F. Beltram, and S. Heun Low-temperature quantum transport in CVD-grown single crystal grapheme, Nano Research, 9, 1823 (2016)
S. Xiang, A. Mrenca-Kolasinska, V. Miseikis, S. Guiducci, K. Kolasinski, C. Coletti, B. Szafran, F. Beltram, S. Roddaro, and S. Heun Interedge backscattering in buried split-gate-defined graphene quantum point contacts, Phys. Rev. B, 94, 155446 (2016)
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Artistic picture of the molecular transistor realized with graphene-based electrodes. Color scale map of the differential conductance measured as a function of the source-drain voltage and of the applied magnetic field.
S. Lumetti, A. Candini, C. Godfrin, F. Balestro, W. Wernsdorfer, S. Klyatskaya, M. Ruben, and M. Affronte Single-molecule devices with graphene electrodes, Dalton Trans., 45, 16570-16574 (2016)
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2. Hybrid superconductor-normal devices as current standard: the superconducting quantum interference single electron turnstile (SQUISET).
Contact person:
Francesco Giazotto
A new concept of single electron transistor is proposed based on the coherent control of the energy gap induced in the source and drain electrodes. The quantum stability of the single electron states combined with the fast operations of the turnstile makes this transistor a promising candidate for future definitions of a current standard.
3. Quantum Metrology in the presence of noise.
Contact person:
Alessandro Braggio
The intrinsic limits of metrology systems based on quantum technology are analyzed from a theoretical point of view.
4. Generation and characterization of metrologically relevant nonclassical states (such as Schrödinger or spin-squeezed states) in ensembles and in single molecular nanomagnets.
Contact person:
Marco Affronte
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