B. SPIN QUBIT, QUANTUM SENSORS AND HEAT MANIPULATION
1. Electrostatic manipulation of individual spins and orbital energies.
Contact person:
Francesco Rossella
Stefano Roddaro
Nanoscale structures such as semiconductor nanowires and graphene nanostructures (including nanoribbons, GNRs) are used to implement devices in which transport is controlled by the state of individual electrons trapped in quantum dots. Individual spins are used to store quantum information and/or to implement quantum gates and sensors.
2. Molecular spins for Quantum technology.
Contact person:
Filippo Troiani
Marco Affronte
Single molecular spins are embedded within an electronic circuit by the realization of single magnetic molecule junctions, to address and manipulate individual electronic and even nuclear spins. The final task is to implement quantum gates and quantum sensors and/or realize quantum memories exploiting the long coherence time of molecular materials.
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Artistic view of the molecular spin transistor with the magnetic molecule (TbPc2) embedded between the gold electrodes. Schematics of the molecular system.
F. Troiani, C. Godfrin, S. Thiele, F. Balestro, W. Wernsdorfer, S. Klyatskaya, M. Ruben, and M. Affronte Landau-Zener transition in a continuously measured single-molecule spin transistor, Phys.Rev., 118, 25701 (2017)
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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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3. Spin impurities for quantum technologies.
Contact person:
Marco Affronte
Molecular spin doping is used to generate spin polarized superconducting states of particular interest to activate the unconventional topological superconductivity of fundamental interest for the generation of Majorana bound states.
4. Heat control in solid-state nanostructures (Coherent Caloritronics).
Contact person:
Francesco Giazotto
Caloritronics is a central issue at the nanoscale, where heat dynamics plays a crucial role in determining the properties of the system and is crucial for the correct operations of the complex quantum networks of efficient quantum computers. Coherent effects on hybrid systems are exploited to have a precise and fast control of the heat at the nanoscale.
5. Quantum control of thermoelectric properties and thermal exchanges in nanostructures.
Contact person:
Fabio Taddei
Nanoscale thermoelectrics is studied which offers today a novel route to the realization of solid-state energy converters with dramatically enhanced thermodynamic efficiencies, and is also relevant to minimize dissipative phenomena and decoherence
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Power factor Q and figure of merit ZT plotted as a function of the electrochemical potential μ (gate voltage) for a multi-level QD.
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Comparison between the thermal conductance of an interacting and a non-interacting QD, plotted as a function of the electrochemical potential μ..
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P. A. Erdman, F. Mazza, R. Bosisio, G. Benenti, R. Fazio, and F. Taddei, Thermoelectric properties of an interacting quantum dot based heat engine, Phys. Rev. B, 95, 245432 (2017).
6. New prospects for quantum electron microscopy (QEM).
Contact person:
Vincenzo Grillo
Quantum experiments with state preparation, controlled interaction, and final state analysis are performed in a transmission electron microscope. This offers the unprecedented possibility to approach the few or single electron limit for the measurement of a given property
7. Temperature estimation via local measurements.
Contact person:
Vittorio Giovannetti
We have introduced a functional which measures the highest achievable accuracy in the estimation of the temperature of a system at thermal equilibrium via local measurements. In the low temperature regime, the above local measurements approach offers a way to characterize the local distinguishability between the quantum states corresponding to the lowest and the first excited levels of the system Hamiltonian. Such technique can be exploited to build up and control quantum memories.
8. Optomechanical and ultra-cold atoms quantum heat engines.
Contact person:
Gioacchino Massimo Palma
The main research objective is to conceive optomechanical devices which are able to convert heat into coherent mechanical vibrations of a nano-resonator. In particular we are interested in generalizing the notions of work, efficiency, power, etc. from the classical to the quantum regime. This is a non-trivial task due to the lack of a classical phase-space description for quantum systems.
9. Heat mastering, thermal logic, and thermal memories in coherent caloritronics.
Contact person:
Francesco Giazotto
Phase-coherent caloritronics takes advantage of long-range phase coherence in superconducting condensates to manipulate heat currents in solid-state mesoscopic circuits. The fundamental idea is to exploit suitable physical effects that depend on the superconducting phase difference, in order to control the electronic heat flow between two thermal reservoirs residing at different temperatures.
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Pseudo-color scanning electron micrograph of the 0-pphase-controllable thermal Josephson junction (JJ). Inset:enlargedimageoftheSQUID,composedofthreeJJs.
A. Fornieri, G.Timossi, P. Virtanen, P. Solinas, and F. Giazotto, 0–p phase-controllable thermal Josephson junction, Nature Nanotech, 12, 425-429 (2017).
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