Category Archives: Seminars

Tommaso Tufarelli visiting AQM

Tommaso Tufarelli, from University of Nottingham, is visiting AQM from Tuesday 10 to Thursday 12 January.

He will deliver a talk on Wednesday, 11 January at 12:30 in Auletta Ottica Quantistica (5 piano LITA)

Refining the Dicke Model

I will start by reviewing an interesting signature of the “A^2 term” in a simple Dicke model featuring two coupled oscillators [first reported in Phys. Rev. A 91, 063840 (2015)]. Then, I will discuss conditions under which such model could be derived as an approximation to a minimal coupling Hamiltonian in Coulomb-gauge, showing that some additional Hamiltonian terms, not usually discussed in the literature, should be present in the ultrastrong coupling regime.

Andrea Smirne visiting

Andrea Smirne, from Ulm University, will be visiting the Physics Department from Monday, 12 December. He will give a lecture and a talk about quantum parameter estimation.

Monday 12 December, 8.45,  Aula I

Lecture Classical and quantum limits to the achievable precision in parameter estimation

Wednesday 14 December, 13.30, Aula Bonetti

Seminar Overcoming the classical limits for frequency estimation in the presence of a general class of open-system dynamics

Continue reading Andrea Smirne visiting

The Big Bell Test

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The BIG Bell Test (BBT) is a worldwide project to bring human unpredictability (randomness) to cutting-edge physics experiments. It may be surprising, but there are aspects of physical reality that can only be understood by asking unpredictable questions of nature. The most famous experiment of this kind is the Bell test. In the BBT, laboratories around the world (see map) will prepare entangled quantum particles: electrons, photons, atoms, and superconductors. Through the Internet, an army of participants, the Bellsters, will shower these particles with unpredictable, high-speed “questions” (measurements, in fact). Together, we will perform unique quantum physics experiments, including the first human-driven Bell test.

The experiments will all take place on Wednesday, November 30th and everyone can contribute by going to the project website and playing the games proposed.

Claudia Benedetti, Marco Genoni and Stefano Olivares from the Applied Quantum Mechanics Group will give an introductory seminar aimed at high-school and university students on Tuesday, November 29th at 14:30 in Aula A of the Physics Department.

Here are the slides of the seminar:
Intro di meccanica quantistica (Olivares)
BIG Bell Test (Benedetti, Genoni)

A blog article on the experiment by Matteo Rossi:
https://www.tomshw.it/big-bell-test-la-meccanica-quantistica-ha-bisogno-di-voi-81653

Further material is available on the ICFO website:
http://outreach.icfo.eu/media/upload//arxius/BBT/quantum_eng.pdf

PhD Seminars 2016

Here the calendar of PhD seminars 2016.

First-year students will present their research work during the PhD student Workshop on October 20 in Aula Consiglio.

Francesco Albarelli: Nonclassicality in continuous variables quantum systems.

Luigi Seveso: Ultimate precision: new developments in quantum estimation theory.

Giacomo Tanzi Marlotti: How to analyse condensed matter with Positronium.

The other students will give seminars in room A5/S2, fifth floor, LITA building.

Thursday, October 6, 13:00
Jacopo TrapaniOptimized protocols for discrimination of collective decoherence with classical environment

Thursday, October 6, 13:30
Matteo RossiProbing the diamagnetic term in light-matter interaction

Friday, November 18, 10:15
Giacomo Guarnieri: Characterization of heat in non-Markovian open quantum systems

and non-Markovian quantum jumps. Seminar about the 51th Winter School of Theoretical Physics (Ladek Zdroj)

Zeudi Mazzotta: Ps spectroscopy in the AEGIS experiment: a spectral analysis

and Applications of lasers in Medicine and Life Sciences, seminar about the school  LAMELIS – Advanced summer school on Lasers in Medicine and Life Sciences (Szeged, Hungary)

Talk by Matteo Brunelli on Tue, Oct 25

Matteo Brunelli (Queen’s University Belfast) will be visiting us from 24 to 28 October 2016.

He will give a talk on Tuesday 25 October at 12 am in Aula Ottica Quantistica (A5/S2), 5th floor, LITA building, entitled:

Irreversibility and correlations in mesoscopic quantum systems: an optomechanical route

Abstract

In this talk I will present a theoretical framework to assess the degree of irreversibility of a dissipative process acting on an interacting quantum system. In particular, the entropy production rate of coupled quantum harmonic oscillators can be expressed in a simple form. I will apply the result to the analysis of the optomechanical interaction between a nano-mechanical resonator and a cavity field, and show the agreement between the predictions of our framework and experimental data.  In the second part, I will present a quantitative relation between the entropy production rate and the correlations, both total and quantum, built between the mechanical resonator and the cavity field.

Steve Campbell talk on Thu, July 21

Next week Steve Campbell from Queen’s University Belfast will be visiting AQM. He will give a talk on Thursday, July 21, 14.00 at Aula Ottica Quantistica (5 piano LITA).

The cost of achieving finite time adiabatic dynamics

Recent years have witnessed a surge of interest in the study of thermal nanomachines that are capable of converting disordered forms of energy, such as heat, into useful work. It has been shown for both classical and quantum systems that external drivings can allow a system to evolve adiabatically even when driven in finite time, such techniques are commonly known as shortcuts to adiabaticity (STA) [1].

It was suggested to use such external drivings to render the unitary processes of a thermodynamic cycle quantum adiabatic, while being performed in finite time [2]. This could considerably augment the performance of nano-thermodynamic engines as work exchanges are extremised by adiabatic protocols. However, implementing additional external driving requires resources which affect the overall performance of the system [3].

We analyse the implications of considering the necessary power in applying these STA subsequently showing that this cost may outweigh the possible gains in work extraction for slow enough processes due to the relative degree of adiabaticity in the dynamics, while for relatively faster processes, the use STA can improve the work exchange. Furthermore, we devise a general strategy that exploits the definition of work as a two-time measurement of energy to improve the performance of work transfer. In particular, we show that it is possible to achieve sizable energy savings by gathering information from the first measurement and then applying a specifically tailored driving to the protocol. We apply our framework to driving a critical many-body system through a quantum phase transition, where the closing of the energy gap at the critical point makes the driving Hamiltonian of increasing complexity [4] and show that this complexity necessitates a divergence in the cost of achieving finite time adiabatic dynamics.

References:

[1] Shortcuts to adiabaticity, E. Torrontegui, S. Ibáñez, S. Martínez-Garaot, M. Modugno, A. del Campo, D. Guéry-Odelin, A. Ruschhaupt, Xi Chen, and J. G. Muga, Adv. At. Mol. Opt. Phys. 62, 117-169 (2013).

[2] More bang for your buck: Towards super-adiabatic quantum engines, A. del Campo, J. Goold, and M. Paternostro, Sci. Rep. 4, 6208 (2014).

[3] Cost of transitionless driving and work output, Yuanjian Zheng, Steve Campbell, Gabriele De Chiara, and Dario Poletti, arXiv:1509.01882.

[4] Shortcut to Adiabaticity in the Lipkin-Meshkov-Glick Model, S. Campbell, G. De Chiara, M. Paternostro, G. M. Palma, and R. Fazio, Phys. Rev. Lett. 114, 177206 (2015).

Steve Campbell talk on Wed, April 6th

We announce the following talk, to be held on Wed, April 6th at 2.30 PM in Aula Polvani

Steve Campbell – Queen’s University Belfast

Non-equilibrium thermodynamics, equilibration, and thermometry of trapped cold atoms

Trapped ensembles of bosonic atoms represent an ideal candidate to simulate some of the most interesting aspects in the phenomenology of thermalisation and equilibration in quantum systems. In this talk I will focus on two widely applicable settings, namely harmonically trapped bosons and a loaded double well potential, and use the framework of non-equilibrium thermodynamics to the study the role quantum features play in setting the dynamic and static properties of the systems. I will attempt to show some qualitative evidence for the relation between the creation of entanglement and work performed on the system, and the relation to other interesting quantum phenomena such as Anderson’s Orthogonality catastrophe. Meanwhile, a quantum system’s ability to equilibrate and the role (or seeming lack there of) that genuinely quantum features play will also be presented. Finally, some recent progress in thermometry schemes for the double-well will be discussed.