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06/06/2017 10:15Integrable systems, having an extensive number of conserved quantities, are typically associated with ballistic transport. This picture is theoretically justified in terms of Mazur bounds [1], or the emerging field of generalized hydrodynamics [2]. However, for systems posessing parity-type symmetries (such as spin-reversal or parity-hole) there exist generic symmetric states for which...Go to contribution page
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06/06/2017 11:45This joint work with R. Azouit, F. Chittaro and A. Sarlette consider a composite quantum system consisting of a fast dissipative subsystem coupled to a slow one. Using the time-scale separation, we develop an adiabatic elimination technique to derive at any order the reduced model describing the slow subsystem. The method, based on an asymptotic expansion and geometric singular perturbation...Go to contribution page
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06/06/2017 14:00Quantum trajectories describe the evolution of a quantum system monitored by indirect measurement. The evolution is random and is usually described by Markov processes, either solution of stochastic differential equations or Markov chains. It is then natural to study the large time behaviour of such evolution, this is related to the notion of invariant measure. In this talk we present...Go to contribution page
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06/06/2017 15:00Decoherence can be understood as the result of unread measurements of the system by its environment. For a superconducting qubit, the two main corresponding jump operators are the lowering operator and the Hamiltonian operator. While the former is associated with the detection of an emitted photon by fluorescence, the latter can be associated with the detection of a frequency shift of a...Go to contribution page
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06/06/2017 16:30Einstein’s General Relativity applied to black holes appears to lead to Information loss, thus violating one of the fundamental tenets of Quantum Mechanics. Recent Quantum Information Theory based arguments imply that information loss can only be avoided if at the scale of the black hole horizon there exists a structure (commonly called fuzzball or firewall) that allows information to escape....Go to contribution page
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07/06/2017 09:30We perform experiments where photons are trapped in a nearly ideal “photon box” as discussed by Einstein and Bohr in one of the gedanken experiments they introduced for emphasizing the unbelievable strangeness of quantum theory. Our photon box consists in a high Q cavity trapping microwave photons between superconducting mirrors. In the experiments, we probe and manipulate the trapped...Go to contribution page
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07/06/2017 10:30We will consider the phenomenon of quantum entanglement from the point of view of high-dimensional convex geometry. We estimate several geometric invariants (volume, mean width, approximability by polytopes) associated with the convex set consisting of all unentangled quantum states, and with the dual set. This information can be translated into results about the complexity of entanglement, or...Go to contribution page
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07/06/2017 12:00Recent advances in quantum-limited amplification have opened doors to high-fidelity non-demolition measurement of superconducting qubits and have already led to successful experiments on closed-loop control of such systems. However, the finite bandwidth of the amplification procedure, together with the time-consuming data acquisition and post-treatment of the output signal, lead to important...Go to contribution page
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07/06/2017 14:15In this talk we give a brief survey on ways to encode quantum information in order to protect it against decoherence and noise. We will give a quick overview of quantum error correction with it's challenges and applicability, and then describe an alternative way to avoid decoherence: decoherence-free subspaces. We will focus on the 3-qubit exchange qubit and also give a surprising connection...Go to contribution page
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07/06/2017 15:15Continuous measurement schemes have an interest beyond the simple unraveling of an open system evolution as they allow for control. Indeed, a certain function of the past measurement signal can be fed back into the system through an external drive to provide e.g. a controllable dissipation source, stabilize a state or purify it faster. However, very few situations yield a manageable master...Go to contribution page
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07/06/2017 16:45We have introduced, some time ago, an experimental system in which a droplet bouncing on a vertically vibrated liquid interface can become self-propelled by its interaction with the waves it generates. It thus becomes a self-propelled "walker", a symbiotic object formed by the droplet and its associated wave. A specificity of this system is that owing to the parametric forcing due to the...Go to contribution page
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08/06/2017 09:30The detection and characterization of paramagnetic species by electron-spin resonance (ESR) spectroscopy has numerous applications in chemistry, biology, and materials science [1]. Most ESR spectrometers rely on the inductive detection of the small microwave signals emitted by the spins during their Larmor precession into a microwave resonator in which they are embedded. Using the tools...Go to contribution page
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08/06/2017 10:30I report on results concerning the stochastic dynamics of quantum systems featuring events and of systems under repeated observation. In particular, I will mention a new type of "quantum branching process" (apparently not studied by mathematicians, yet) and outline a theory of indirect measurements and of associated quantum jump processes.Go to contribution page
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08/06/2017 12:00In a quantum fluid such as a condensed Bose gas, elementary excitations such as phonons behave as quantized fields with dispersion relations and non-linearities that bear some resemblance to those of the electromagnetic field. The very low temperatures of these gases means that in some cases quantum fluctuations are important. Several remarkable phenomena in quantum electrodynamics have found...Go to contribution page
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08/06/2017 13:00I shall give an introduction to Open Quantum Walks, which are a new type of quantum walks, implementing dissipation. I shall relate them to the usual (unitary) quantum walks and show that there exists a very interesting type of quantum walks interpolating in between the two. One knows very very few things about these interpolating quantum walks.Go to contribution page
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