Séminaires du jeudi 22 mars

Séminaire du LPTMS: Mario Collura *** séminaire exceptionnel ***


Full counting statistics out of equilibrium: melting of antiferromagnetic order

Mario Collura (Oxford University, UK)

One of the basic principles of quantum mechanics is the statistical nature of measurements of observables. The result of measurements is indeed described by a probability distribution, and measuring the same observable  in identical systems will give different outcomes in accordance with this distribution.  The full probability distribution carries very detailed information about the system and, on top of expectation value, encodes all fluctuations of the system.  I will focus on the non-equilibrium dynamics of a fully polarised antiferromagnetic state under the unitary evolution induced by the XXZ Hamiltonian. It turns out that, depending on the value of the interactions, the full probability distribution of the subsystem staggered magnetisation may retain informations about the original antiferromagnetic order, thus acquiring a shape much different from a simple Gaussian distribution.

Séminaire du LPTMS: Simon Pigeon *** séminaire exceptionnel ***


Vibrational assisted conduction in a molecular wire

Simon Pigeon (LKB, UPMC, Paris)

I will present a detailed study of the conduction properties of a molecular wire where hopping processes between electronic sites are coupled to a vibrational mode of the molecule. This description is inspired by the idea that physically the vibrational mode does not need to change the energetic structure of the electronic part but can just perturb the exchange taking place on this subsystem. It is shown that the presence of the vibrational system can give rise to strong enhancement of the wire conductivity. Moreover through the control of the vibrational properties (temperature and position) one can accurately control the electronic flux crossing the device. An increase of the temperature enhances the conduction, while the control of the equilibrium position of the oscillator can switch on and off the conduction.

This work establishes how vibrational coupled hopping affects the electronic properties of a molecular wire. These crucial results pave the way to a better understanding and more complete description of electronic properties of these promising devices.

  • S. Pigeon, L. Fusco, G. De Chiara & M. Paternostro, Vibrational assisted conduction in a molecular wire, Quantum Science and Technology 2, 025006 (2017) ; arXiv:1612.01809