Upcoming seminars

Theory of classical and quantum frustration in quantum many-body systems

Seminar date and time: 
2011-03-31 12:30 to 13:30
Author: 
Alex Monras
Affiliation: 
GIQ, UAB

We present a general scheme for the study of frustration in quantum systems. After introducing a universal measure of frustration for arbitrary quantum systems, we derive for it an exact inequality in terms of a class of entanglement monotones. We then state sufficient conditions for the ground states of quantum spin systems to saturate the inequality and confirm them with extensive numerical tests.

Location: 
IFAE Seminar Room

Multi-copy programmable discrimination of general qubits

Seminar date and time: 
2011-03-21 10:00 to 11:00
Author: 
Gael Sentís
Affiliation: 
GIQ

Quantum state discrimination is a fundamental primitive in quantum statistics where one has to correctly identify the state of a system that is in one of two possible known states. A programmable discrimination machine performs this task when the pair of possible states is not a priori known but instead the two possible states are provided through two respective program ports. We study optimal programmable discrimination machines for general qubit states when several copies of states are available in the data or program ports.

Location: 
IFAE Seminar Room

All-versus-nothing proofs with n qubits distributed between m parties

Seminar date and time: 
2011-03-11 13:00 to 14:00
Author: 
Pilar Moreno
Affiliation: 
Universidad de Sevilla

All-versus-nothing (AVN) proofs [1--6] show the conflict between Einstein, Podolsky, and Rosen's (EPR) elements of reality [7] and the perfect correlations of some quantum states. The name of "all-versus-nothing" [8] reflects a particular feature of these proofs: If one consider a set of perfect correlations and asumes EPR elements of reality, then a subset of these correlations leads to a conclusion that is opposite of the one obtained from the complementary subset of correlations.

Location: 
Sala de Graus II

Learning class on DMRG

Seminar date and time: 
2011-03-08 10:00 to 11:00
Author: 
Gabriele De Chiara
Affiliation: 
GIQ (UAB)

As a follow-up to the lectures on DMRG, somebody might be interested in a more practical session to learn the use of the DMRG code in fortran we currently use in the simulations. The code can be found here: www.dmrg.it In this class, I will explain how to use the DMRG code for finding the ground state of the one-dimensional Bose-Hubbard model. I will discuss the ground state energy, the gap, the phase diagram and the correlators.

Location: 
IFAE Seminar Room

Optimal quantum estimation of the Unruh-Hawking effect.

Seminar date and time: 
2011-02-28 09:00 to 10:00
Author: 
Mariona Aspachs
Affiliation: 
GIQ (UAB)

The Unruh effect is one of the most fundamental manifestation of the fact that the particle content of a field theory is observer dependent. We will address on general quantum-statistical grounds the problem of optimal detection of the Unruh-Hawking effect. The effect signatures are magnified up to potentially observable levels if the scalar field to be probed has high mean energy from an inertial perspective: The Unruh-Hawking effect acts like an amplification channel.

Location: 
IFAE Seminar room

Short introduction to the Gutzwiller approximation in many-body physics

Seminar date and time: 
2011-02-11 14:00 to 15:00
Author: 
Simone Paganelli
Affiliation: 
GIQ (UAB)

The zero-temperature properties of a many-body system can be studied by  variational methods. For strongly correlated particles in a lattice,  Gutzwiller approximation provides an ansatz for the ground state which is quite accurate in predicting  the transition between Mott insulating and conducting phases. In this seminar, a general formulation of the method will be given together with some relevant examples. The connection with standard mean field theory and the limitations of this approximation will be also  discussed.

Location: 
Aula C5/012 (Facultat Ciències, UAB)

Numerical methods in many-body physics: an introduction to DMRG & Co II

Seminar date and time: 
2011-02-11 13:00 to 14:00
Author: 
Gabriele De Chiara
Affiliation: 
GIQ (UAB)

I will present a survey on the many-body problem and some numerical techniques to deal with it. In particular I will concentrate on the density matrix renormalization group algorithm, describing its capabilities, limitations and recent breakthroughs inspired by Quantum Information theory.

References:
U. Schollwöck, The density-matrix renormalization group in the age of matrix product states, Ann. Phys. (NY) 326, 96 (2011).

U. Schollwöck, The density-matrix renormalization group, Rev. Mod. Phys. 77, 259 (2005).

Location: 
Aula C5/012 (Facultat Ciències, UAB)

Numerical methods in many-body physics: an introduction to DMRG & Co I

Seminar date and time: 
2011-02-04 13:00 to 14:30
Author: 
Gabriele De Chiara
Affiliation: 
GIQ (UAB)

I will present a survey on the many-body problem and some numerical techniques to deal with it. In particular I will concentrate on the density matrix renormalization group algorithm, describing its capabilities, limitations and recent breakthroughs inspired by Quantum Information theory.

References:
U. Schollwöck, The density-matrix renormalization group in the age of matrix product states, Ann. Phys. (NY) 326, 96 (2011).

U. Schollwöck, The density-matrix renormalization group, Rev. Mod. Phys. 77, 259 (2005).

Location: 
IFAE Seminar Room

Double-Slit Experiments and Vibrational Control in Non-Polar Molecules

Seminar date and time: 
2011-01-26 10:00 to 11:00
Author: 
Antonio Picón
Affiliation: 
JILA and Department of Physics, University of Colorado (Boulder, USA)

The advent of intense lasers with long wavelengths (on the order of microns) is allowing to have access to a novel control of molecules. We focus on the coherent control of vibrational states of the hydrogen molecular ion in the multiphoton processes regime. Moreover, such intense laser can generate high-harmonics; attosecond pulses (10^-18 s) with high-frequency, a suitable time scale to explore the electron and nuclear dynamics in molecules.

Location: 
IFAE Seminar room

Optomechanics: challenging quantum mechanics at the mesoscale

Seminar date and time: 
2011-01-17 14:00 to 15:00
Author: 
Oriol Romero-Isart
Affiliation: 
Max-Planck-Institut für Quantenoptik

In this talk I will give a general motivation and introduction to the field of quantum optomechanics. I will then focus on our recent proposal to use optically levitating microspheres inside an optical cavity as an optomechanical system without clamping losses. I will review this proposal and explain some particular applications and further directions.

Location: 
Sala de Graus II
Contact: 
julsta@ifae.es

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