Seminars
Upcoming seminars
Past seminars
Seminar by John Gough, Aberystwyth Quantum Structures, Information and Control (AQStIC), Aberystwyth University, Aberystwyth, United Kingdom.
Title : Quantum feedback networks and autonomous quantum error correction.
Date : May 24th, 14:30
Location : Institut Henri Poincaré, 11 Rue Pierre et Marie Curie, 75005 Paris, amphithéâtre Darboux.
Two seminars by Liang Jiang, Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA.
Titles and dates :
- "Quantum control of superconducting circuits" on May 22nd, 14:30,
- "Bosonic quantum error correction" on May 23rd, 14:30.
Location : Institut Henri Poincaré, 11 Rue Pierre et Marie Curie, 75005 Paris, amphithéâtre Darboux.
Seminar by John Gough, Aberystwyth Quantum Structures, Information and Control (AQStIC), Aberystwyth University, Aberystwyth, United Kingdom.
Title : Quantum feedback networks and autonomous quantum error correction.
Date : May 24th, 14:30
Location : Institut Henri Poincaré, 11 Rue Pierre et Marie Curie, 75005 Paris, amphithéâtre Darboux.
Seminar by Gunther Dirr, Univ. Würzburg, Germany
Title : Controlling parallel connections of bilinear systems with applications to quantum control.
Date : June 1, 10.30
Location : Institut Henri Poincaré, 11 Rue Pierre et Marie Curie, 75005 Paris, amphithéâtre Darboux
Seminar by Anthony Bloch, University of Michigan, USA
Title : Control, Geometry and Optimality of Quantum systems with Dissipation
Abstract : In this talk we discuss aspects of the mathematics, control and geometry of quantum control systems interacting with their environment. In particular we discuss the control of a finite-dimensional dissipative Lindblad system by considering the geometry of its orbit and interorbit dynamics. This entails considering the geometry of the system, the structure of the Lindblad operator, and the convexity associated with the density equation. Applications are given to constructing pure states. We discuss controllability and also discuss optimality and optimal control in this setting.
Date : June 14, 14.30
Location : Institut Henri Poincaré, 11 Rue Pierre et Marie Curie, 75005 Paris, amphithéâtre Darboux
Seminar by Tomáš Opatrný, Department of Optics, Faculty of Natural Science, Palacký University, Olomouc, Czech Republic
Title : Asymmetric Foucault pendulum dynamics with analogies to the Lipkin-Meshkov-Glick quantum phase transitions and other quantum phenomena
Abstract : Stokes parameter formalism is applied to show the analogies between the motion of an asymmetric Foucault pendulum and several phenomena known from optics and atomic physics. Nonlinearity-induced precession of elliptical orbits of the pendulum is shown to correspond to twisting transformations used for spin squeezing of atomic systems. Transitions between regimes of predominant nonlinearity and regimes where the Coriolis force or the asymmetry of the pendulum are dominant correspond to quantum phase transitions in the Lipkin-Meshkov-Glick model. A Foucault pendulum with highly anisotropic damping can emulate an optical Zeno effect where a sequence of polarizing filters inhibits polarization rotation of light in an optically active medium.
Date : June 22, 14:30
Location : Institut Henri Poincaré, 11 Rue Pierre et Marie Curie, 75005 Paris, amphithéâtre Darboux.
Seminar by Tomáš Opatrný, Department of Optics, Faculty of Natural Science, Palacký University, Olomouc, Czech Republic
Title : From tennis racket instability to spin squeezing and quantum phase transitions: quantum-classical analogies
Abstract : We show that the classical model of Euler top (freely rotating, generally asymmetric rigid body), possibly supplemented with a rotor, corresponds to a generalized Lipkin-Meshkov-Glick (LMG) model describing phenomena of various branches of quantum physics. Classical effects such as free precession of a symmetric top, Feynman’s wobbling plate, tennis-racket instability and the Dzhanibekov effect, attitude control of satellites by momentum wheels, or twisting somersault dynamics, have their counterparts in quantum effects that include spin squeezing by one-axis twisting and two-axis countertwisting, transitions between the Josephson and Rabi regimes of a Bose-Einstein condensate in a double-well potential, and other quantum critical phenomena. The parallels enable us to expand the range of explored quantum phase transitions in the generalized LMG model, as well as to present a classical analogy of the recently proposed LMG Floquet time crystal.
Date : June 28, 14:30
Location : Institut Henri Poincaré, 11 Rue Pierre et Marie Curie, 75005 Paris, amphithéâtre Darboux.
Seminar by Alberto Delgado, National University of Colombia, Bogota,
Title : Quantum Circuits as Trainable Maps
Date : June 29, 10:30
Location : Institut Henri Poincaré, 11 Rue Pierre et Marie Curie, 75005 Paris, amphithéâtre Darboux.
Seminar by Daoyi Dong, School of Engineering and Information Technology, University of New South Wales, Australia
Title : Efficient state estimation and Hamiltonian identification in quantum systems
Abstract : In this talk, I will introduce several results on quantum state estimation and Hamiltonian identification with my collaborators. First, an efficient method of linear regression estimation (LRE) is presented for quantum state tomography. Numerical examples show that LRE is much faster than maximum-likelihood estimation for quantum state tomography. Second, we present a two-step optimization quantum Hamiltonian identification algorithm, characterize its computational complexity and establish an error upper bound. Lastly, we generalize the identifiability test method based on Similarity Transformation Approach in classical control theory and extend it to the domain of quantum Hamiltonian identification.
Date : June 29, 14:30
Location : Institut Henri Poincaré, 11 Rue Pierre et Marie Curie, 75005 Paris, amphithéâtre Darboux.
Seminar by Lorenza Viola, Department of Physics and Astronomy, Dartmouth College, Hanover, USA.
Title : Advances and Challenges in Markovian Quantum State Stabilization under Resource Constraints
Abstract : Dissipative quantum control techniques are attracting increasing attention in quantum information processing. I will focus on the task of designing Markovian dynamics which admits a desired pure entangled state as its unique stable steady state, subject to specified quasi-locality constraints. While the problem is well understood in a setting where purely dissipative dynamics suffice, and stabilizable pure states may be identified with unique ground states of frustration-free quasi-local Hamiltonians, a characterization of the general case where Hamiltonian and dissipative control must be simultaneously employed has been lacking. I will present necessary and sufficient conditions filling this gap. Somewhat surprisingly, it follows that unique ground states of frustrated quasi-local Hamiltonians need not be stabilizable using quasi-local resources alone. I will illustrate this through an explicit example involving W-states, and discuss alternative strategies, when quasi-local stabilization is not feasible.
Date : July 11, 14:30
Location : Institut Henri Poincaré, 11 Rue Pierre et Marie Curie, 75005 Paris, amphithéâtre Darboux.
