Understanding the physics of nano-devices offers the fascinating opportunity to explore quantum properties of matter at the mesoscopic level. Besides their fundamental impact on modern technology, quantum coherence and strong interactions play a fundamental role in these systems. CMSP research topics include charge and heat transport, thermoelectric effects, nanoelectromechanical systems, quantum coherent electronics and spintronics, solid-state quantum information processing, and low-dimensional systems with interactions.
Some of the distinct features of nanostructures appear in their electronic and heat transport mechanisms. Many of these systems have properties that arise from two main ingredients, phase coherence and strong local correlations. CMSP researchers currently study several of these systems and mechanisms. Including transport through quantum dots and wires, hybrid structures, molecular transistors, topological superconductors, spintronic and nanoelectromechanical systems. In nanoelectromechanics both fundamental and applied aspects are investigated. Phase coherent nanostructures are also studied for their important role in newly emerging quantum technologies, such as solid state quantum computation. Ballistic electron transport in nanocontacts through magnetic impurities including adsorbed radical molecules, is studied by combining the many-body physics of the Kondo effect, with parameters obtained from ab initio electronic structure and methods.
Parallel to the development of the theory of quantum information, since many years, there is an ongoing interest in finding physical systems where quantum information processing could be implemented. In an ideal situation, one should identify a suitable set of two-level systems (sufficiently decoupled from any source of decoherence) with some controllable couplings among them, needed to realize single qubit and two-qubit operations. The quest for large scale integrability and flexibility in the design, has promoted nanostructures among the most promising platforms for quantum information processing. Researchers at CMSP are locking into the properties (and protocols) of solid-state qubits, both in semiconducting and superconducting nano-devices.
Do thermal machines retain their properties when they are scaled down to dimensions where quantum mechanical effects are prominent? This question embraces a number of important aspects of heat and work conversion in small devices, ranging from fundamental problems in determining the ultimate limits, to the mode of operation of thermal machines, to more applied aspects of heat control at the nanoscale. In the CMSP section we are currently interested in those questions and actively studying the properties of quantum heat engines.
Sliding friction and mechanical dissipation, a subject of enormous practical importance in technology, was until recently viewed mostly at the macroscale. Which have turned into a lively microscopic physics playground after the advent of nanoscale tools such as, Atomic Force Microscopes, Surface Force Apparatuses, Quartz Crystal Microbalances, etc. Understanding nanofriction is a challenge because of its non-equilibrium physics. Tackling this challenge can potentially lead to identify the mechanism for its control. Current approaches in the ICTP-SISSA extended group, also sustained by an European Research Council Advanced Grant, move on three fronts. The first is addressing individual problems posed by experiments, mostly by means of classical non-equilibrium molecular dynamics. This area includes the superlubric sliding of clusters, nanotubes, and charge-density-wave systems. The second addresses the role of quantum mechanics in nanofriction, including the building of an ab-initio approach to electronic friction, and quantum phenomena in the sliding of atomic ion chains. The third front, and the most ambitious, is the building of a bona fide theory of sliding friction, something quite promising which just began.