BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Performance evaluation of device-independent quantum key distribut ion with practical sources DTSTART;VALUE=DATE-TIME:20170717T155000Z DTEND;VALUE=DATE-TIME:20170717T161500Z DTSTAMP;VALUE=DATE-TIME:20260714T221202Z UID:indico-contribution-565-4425@indico.ific.uv.es DESCRIPTION:Speakers: Víctor Zapatero (EI Telecomunicación\, Departament o de Teoría de la Señal y Comunicaciones\, Universidad de Vigo\, Vigo E- 36310\, Spain)\nDevice-independent quantum key distribution aims to provid e users with information-theoretically secure secret keys without any need for characterizing the physical devices. Nevertheless\, there still exist s a big gap between theory and experiments. In this work\, we evaluate the performance of assisted device independent quantum key distribution in a realistic scenario\, that is\, using practical photonic sources and a fini te number of signals exchanged between the two parties. For this task\, we employ recently derived finite key rate formulas against general attacks. Our results are useful to analyze the feasibility of practical device-ind ependent quantum key distribution.\n\nhttps://indico.ific.uv.es/event/2851 /contributions/4425/ LOCATION:Facultad Química (USC) Aula Química General URL:https://indico.ific.uv.es/event/2851/contributions/4425/ END:VEVENT BEGIN:VEVENT SUMMARY:Exact Quantum Change Point Detection DTSTART;VALUE=DATE-TIME:20170717T134000Z DTEND;VALUE=DATE-TIME:20170717T140500Z DTSTAMP;VALUE=DATE-TIME:20260714T221202Z UID:indico-contribution-565-4422@indico.ific.uv.es DESCRIPTION:Speakers: Gael Sentis (Naturwissenschaftlich-Technische Fakult ät\, Universität Siegen\, 57068 Siegen\, Germany)\nSudden changes are ub iquitous in nature. Identifying them is crucial for a number of applicatio ns in biology\, medicine\, and social sciences. Here we take the problem o f detecting sudden changes to the quantum domain. We consider a source tha t emits quantum particles in a default state\, until a point where a mutat ion occurs that causes the source to switch to another state. The problem is then to find out where the change occurred. We determine the maximum pr obability of correctly identifying the change point\, allowing for collect ive measurements on the whole sequence of particles emitted by the source. Then\, we devise online strategies where the particles are measured indiv idually and an answer is provided as soon as a new particle is received. W e show that these online strategies substantially underperform the optimal quantum measurement\, indicating that quantum sudden changes\, although h appening locally\, are better detected globally.\n\nhttps://indico.ific.uv .es/event/2851/contributions/4422/ LOCATION:Facultad Química (USC) Aula Química General URL:https://indico.ific.uv.es/event/2851/contributions/4422/ END:VEVENT BEGIN:VEVENT SUMMARY:Testing fundamentaly binary theories DTSTART;VALUE=DATE-TIME:20170717T131500Z DTEND;VALUE=DATE-TIME:20170717T134000Z DTSTAMP;VALUE=DATE-TIME:20260714T221202Z UID:indico-contribution-565-4328@indico.ific.uv.es DESCRIPTION:Speakers: Adán Cabello (University of Seville)\nFundamentally binary theories are non-signaling general probabilistic theories in which measurements with many outcomes can always be constructed by selecting fr om measurements with two outcomes. We show that\, for any n\, there are qu antum correlations between n-outcome measurements which cannot be explaine d by fundamentally (n-1)-ary theories. Interestingly\, even fundamentally binary theories have never been directly falsified by any experiment. Here we report some current theoretical and experimental efforts for falsifyin g them.\n\nhttps://indico.ific.uv.es/event/2851/contributions/4328/ LOCATION:Facultad Química (USC) Aula Química General URL:https://indico.ific.uv.es/event/2851/contributions/4328/ END:VEVENT BEGIN:VEVENT SUMMARY:Device-independent quantum key distribution with single-photon sou rces DTSTART;VALUE=DATE-TIME:20170717T152500Z DTEND;VALUE=DATE-TIME:20170717T155000Z DTSTAMP;VALUE=DATE-TIME:20260714T221202Z UID:indico-contribution-565-4309@indico.ific.uv.es DESCRIPTION:Speakers: Alejandro Mattar (ICFO - The Institute of Photonic S ciences)\nThis abstract describes a new scheme for Device Independent Quan tum Key Distribution\, a minimalist form of quantum cryptography in which no modeling is made about the internal working of the devices used. The sc heme is appealing as it relies on single-photon sources\, a new-generation technology whose development has boosted lately. When physical imperfecti ons are taken into account\, our scheme largely outperforms all previous p roposals\, opening in this manner a promising avenue for experimental DIQK D implementations. This abstract is suited for a talk at the Quantum Infor mation symposium.\n\nhttps://indico.ific.uv.es/event/2851/contributions/43 09/ LOCATION:Facultad Química (USC) Aula Química General URL:https://indico.ific.uv.es/event/2851/contributions/4309/ END:VEVENT BEGIN:VEVENT SUMMARY:Classical physics and the bounds of quantum correlations DTSTART;VALUE=DATE-TIME:20170717T161500Z DTEND;VALUE=DATE-TIME:20170717T164000Z DTSTAMP;VALUE=DATE-TIME:20260714T221202Z UID:indico-contribution-565-4280@indico.ific.uv.es DESCRIPTION:Speakers: Diego Frustaglia (Universidad de Sevilla)\nThe parti cular set of numerical bounds satisfied by quantum correlations has been i ntensively studied as a plausible gateway to the first principles of quant um theory\, which up to date remain elusive. Here we show that these bound s are indeed not exclusive to quantum theory: for any abstract correlation scenario with compatible measurements\, models built on classical waves p roduce events with probability distributions indistinguishable from those of quantum theory and\, therefore\, share the same bounds. We demonstrate this finding by implementing classical microwaves that propagate along met er-size transmission-line circuits and reproduce the probabilities of thre e emblematic quantum experiments [1]. Our results show that the "quantum" bounds would also occur in a classical universe without quanta\, where cla ssical fields would be the fundamental physical objects. The implications of this observation will be discussed [2].\n\n[1] D. Frustaglia\, J. P. Ba ltanás\, M. C. Velázquez-Ahumada\, A. Fernández-Prieto\, A. Lujambio\, V. Losada\, M. J. Freire\, and A. Cabello\, Phys. Rev. Lett. 116\, 250404 (2016).\n[2] L. Zyga\, 'Quantum' bounds not so quantum after all\, Phys.or g (July 1st\, 2016)\, https://phys.org/news/2016-07-quantum-bounds.html.\n \nhttps://indico.ific.uv.es/event/2851/contributions/4280/ LOCATION:Facultad Química (USC) Aula Química General URL:https://indico.ific.uv.es/event/2851/contributions/4280/ END:VEVENT BEGIN:VEVENT SUMMARY:Relativistic physics and beyond with superconducting circuits DTSTART;VALUE=DATE-TIME:20170717T164000Z DTEND;VALUE=DATE-TIME:20170717T170500Z DTSTAMP;VALUE=DATE-TIME:20260714T221202Z UID:indico-contribution-565-4253@indico.ific.uv.es DESCRIPTION:Speakers: Carlos Sabín (Instituto de Física Fundamental\, CS IC)\nWe will discuss several schemes for simulating relativistic motion in superconducting circuit architectures. As a first example\, we show how t he dynamical modulation of the qubit-field coupling strength in a circuit quantum electrodynamics architecture mimics the motion of the qubit at rel ativistic speeds. This allows us to propose a realistic experiment to dete ct microwave photons coming from simulated acceleration radiation [1]. We show that this accelerated radiation can be used to generate entanglement between a pair of qubits [2]. Moreover\, we discuss the effects of relativ istic motion on single-atom and two-atom Dicke superradiance [2]. Finally\ , we show that it is possible to simulate effective velocities which even exceed the speed of light in the medium\, giving rise to the quantum count erpart of Cerenkov radiation\, namely Ginzburg radiation [3].\nWe propose as well an implementation of a twin-paradox scenario in superconducting ci rcuits\, with velocities as large as a few percent of the speed of light [ 4]. Ultrafast modulation of the boundary conditions for the electromagneti c field in a microwave cavity simulates a clock moving at relativistic spe eds. Since our cavity has a finite length\, the setup allows us to investi gate the role of clock size as well as interesting quantum effects on time dilation. In particular\, our theoretical results show that the time dila tion increases for larger cavity lengths and is shifted due to quantum par ticle creation. \nThe combination of both techniques generates a toolbox f or studying relativistic phenomena in quantum field theory with supercondu cting circuits. We will discuss some possible future applications.\n\nhttp s://indico.ific.uv.es/event/2851/contributions/4253/ LOCATION:Facultad Química (USC) Aula Química General URL:https://indico.ific.uv.es/event/2851/contributions/4253/ END:VEVENT BEGIN:VEVENT SUMMARY:Self-testing of multipartite quantum states DTSTART;VALUE=DATE-TIME:20170717T143000Z DTEND;VALUE=DATE-TIME:20170717T145500Z DTSTAMP;VALUE=DATE-TIME:20260714T221202Z UID:indico-contribution-565-4194@indico.ific.uv.es DESCRIPTION:Speakers: Ivan Supic (ICFO - Institut de Ciencies Fotoniques)\ nA very timely enterprise nowadays is to understand which states can be se lf-tested and how. This question has been answered recently in the biparti te case\, while it is largely unexplored in the multipartite case\, with o nly a few scattered results\, using a variety of different methods: maxima l violation of a corresponding Bell inequality\, numerical SWAP method\, s tabilizer self-testing etc. This also explains why it is not clear which s tates can be self-tested. In our work\, we propose a unifying approach: co mbining projections to two-qubit spaces (projecting parties or degrees of freedom) and then using the maximal violation of tilted CHSH inequalities. In the qubit case\, using this simple but general approach\, we show that almost all multipartite qubit states can be self-tested (albeit with many measurements)\, namely all the ones that can be written with all real coe fficients in some basis. In particular\, this result is enough to characte rize the tripartite case completely. Moreover\, for special classes of mul tipartite states\, like symmetric Dicke states and graph states\, our appr oach yields a self-test with few measurements. Finally\, for the qudit cas e\, we show that all multipartite states which admit a Schmidt decompositi on can be self-tested with few measurements\n\nhttps://indico.ific.uv.es/e vent/2851/contributions/4194/ LOCATION:Facultad Química (USC) Aula Química General URL:https://indico.ific.uv.es/event/2851/contributions/4194/ END:VEVENT BEGIN:VEVENT SUMMARY:Entanglement harvesting: entangling systems via local operations DTSTART;VALUE=DATE-TIME:20170717T140500Z DTEND;VALUE=DATE-TIME:20170717T143000Z DTSTAMP;VALUE=DATE-TIME:20260714T221202Z UID:indico-contribution-565-4165@indico.ific.uv.es DESCRIPTION:Speakers: Alejandro Pozas-Kerstjens (ICFO)\nThe abstract conta ins the overview of the talk that is proposed\, as well as an introduction to the subject of matter and the presenter's contributions to the field.\ n\nhttps://indico.ific.uv.es/event/2851/contributions/4165/ LOCATION:Facultad Química (USC) Aula Química General URL:https://indico.ific.uv.es/event/2851/contributions/4165/ END:VEVENT END:VCALENDAR