Quantum Singular Value Decomposer

We present a variational quantum circuit that produces the Singular Value Decomposition of a bipartite pure state. The proposed circuit, that we name Quantum Singular Value Decomposer or QSVD, is made of two unitaries respectively acting on each part of the system. The key idea of the algorithm is to train this circuit so that the final state displays exact output coincidence from both subsystems for every measurement in the computational basis. Such circuit preserves entanglement between the parties and acts as a diagonalizer that delivers the eigenvalues of the Schmidt decomposition. Our algorithm only requires measurements in one single setting, in striking contrast to the $3^n$ settings required by state tomography. Furthermore, the adjoints of the unitaries making the circuit are used to create the eigenvectors of the decomposition up to a global phase. Some further applications of QSVD are readily obtained. The proposed QSVD circuit allows to construct a SWAP between the two parties of the system without the need of any quantum gate communicating them. We also show that a circuit made with QSVD and CNOTs acts as an encoder of information of the original state onto one of its parties. This idea can be reversed and used to create random states with a precise entanglement structure.Comment: 6 + 1 pages, 5 figure

El País Vasco visto por un comerciante inglés

Transcripción y traducción de un texto en inglés escrito por un comerciante en el que describe Euskadi. Trata de fechar el documento considerando que es de finales del siglo XVII principios del XVIIITranscription and translation of a text in English written by a merchant in which he describes the Basque Country. The author tries to date the document considering that it dates back to the end of the 17th century and beginning of the 17t

From Postmodern Ethics to the New Ethics of the Me Generation: The Transition from Mass Media to the Internet

Postmodernism, a culture of vague boundaries, boosted values such as individualism and superficial character, with the Mass Media as a crucial factor in spreading them. The Internet is an heir of this period, but took on a life of its own, becoming the favourite information source for the population, and also an economic icon. The Internet put an end to the fragmentation of the media and introduced a bidirectional nature to communications. It is a multipurpose tool that generates values and changes (in reading, attention, memory or culture), requiring a critical evaluation of the new Me Generation axiology

Quantum Emulation of Molecular Force Fields: A Blueprint for a Superconducting Architecture

In this work, we propose a flexible architecture of microwave resonators with tunable couplings to perform quantum simulations of problems from the field of molecular chemistry. The architecture builds on the experience of the D-Wave design, working with nearly harmonic circuits instead of qubits. This architecture, or modifications of it, can be used to emulate molecular processes such as vibronic transitions. Furthermore, we discuss several aspects of these emulations, such as dynamical ranges of the physical parameters, quenching times necessary for diabaticity, and, finally, the possibility of implementing anharmonic corrections to the force fields by exploiting certain nonlinear features of superconducting devices.Comment: 14 pages, 4 figure

Photon-mediated qubit interactions in one-dimensional discrete and continuous models

In this work we study numerically and analytically the interaction of two qubits in a one-dimensionalwaveguide, as mediated by the photons that propagate through the guide. We develop strategies to assert the Markovianity of the problem, the effective qubit-qubit interactions, and their individual and collective spontaneous emission. We prove the existence of collective Lamb shifts that affect the qubit-qubit interactions and the dependency of coherent and incoherent interactions on the qubit separation. We also develop the scattering theory associated with these models and prove single-photon spectroscopy does probe the renormalized resonances of the singleand multiqubit models, in sharp contrast to earlier toy models in which individual and collective Lamb shifts cancel

Sexual Division in Parenting: A Normative Context That Hinders Co-Responsibility

Recent decades have seen an increase in women’s employment rates and an expansion of egalitarian values. Previous studies document the so-called “motherhood penalty”, which makes women’s employment more difficult. Demands for greater shared child-rearing between parents are hindered by a normative climate that supports differentiated gender roles in the family. Using data from the Center for Sociological Research [Centro de Investigaciones Sociológicas] (2018), this study shows that the Spanish population perceives that differentiated social images of motherhood and fatherhood still persist. The “sexual division in parenting” index is proposed and the profile of the individuals who most perceive this sexual division is analyzed. The results show that women and younger people are the most aware of this social normativity that unequally distributes child care, making co-responsibility difficult. The political implications of these results are discussed

Quantum Simulation with a Boson Sampling Circuit

In this work we study a system that consists of $2M$ matter qubits that interact through a boson sampling circuit, i.e., an $M$-port interferometer, embedded in two different architectures. We prove that, under the conditions required to derive a master equation, the qubits evolve according to effective bipartite XY spin Hamiltonians, with or without local and collective dissipation terms. This opens the door to the simulation of any bipartite spin or hard-core boson models and exploring dissipative phase transitions as the competition between coherent and incoherent exchange of excitations. We also show that in the purely dissipative regime this model has a large number of exact and approximate dark states, whose structure and decay rates can be estimated analytically. We finally argue that this system may be used for the adiabatic preparation of boson sampling states encoded in the matter qubits.Comment: 9 pages, 3 figure

Shaping an Itinerant Quantum Field by Dissipation

We show that inducing sidebands in the emission of a single emitter into a one dimensional waveguide, together with a dissipative re-pumping process, a photon field is cooled down to a squeezed vacuum. Our method does not require to be in the strong coupling regime, works with a continuum of propagating field modes and it may lead to sources of tunable multimode squeezed light in circuit QED systems.Comment: 4 pages, 3 figure

Hybrid Playground: Integración de herramientas y estrategias de los videojuegos en los parques infantiles

Basándonos en el concepto de ciudad híbrida (entendida como el resultado de la transformación de los actuales modelos de percepción y vivencia de la ciudad a partir del efecto de la integración de sistemas tecnológicos en el espacio público), proponemos la transformación de los parques infantiles urbanos en escenarios para el juego audiovisual interactivo, que propicien el desarrollo de experiencias de juego físico-digitales y dinamicen las relaciones de colaboración entre los usuarios. Los dispositivos de juego urbanos se convierten de esta manera en interfaces audiovisuales tangibles que permiten desarrollar estrategias lúdicas similares a los videojuegos.Based on the idea of hybrid cities (understood as the result of the transformations of the actual models of perception and experience of the city through the effects of the integration of technological systems in the public space), we propose to transform public adventure playgrounds into interactive audiovisual gaming spaces, provoking physical-digital game experiences and facilitating collaborative relations between users. Urban playground devices thus become tangible interfaces that allow for computer game-like experiences

Spanish Twitch streamers: Personal influence in a broadcast model akin to television

Following the migration of influencers from YouTube to Twitch and the boom in popularity experienced by the latter social network, this paper explores if brands are capitalizing on the influence capacity of streamers or if streamers might be getting money from their own content. In order to investigate this, it was necessary to perform a quantitative analysis on the publication schedules and broadcast formats used by streamers. This facilitated the simultaneous identification of another main finding: Spanish streamers are using a broadcast model on Twitch that resembles that of open linear television. Although they only broadcast content related to video games, trends towards other types of audiovisual content have already been identified. Moreover, it has been found that influential streamers prioritize Twitch over other social networks even though feedback flows have been detected, especially from Twitch to other platforms. This work represents a contribution to knowledge in terms of understanding Twitch and understanding platforms and influencers. It is important to determine whether these new forms of broadcasting and interaction could be considered a hybrid model between linear television and social media streaming.This work was supported by Department of Education, University and Professional Training of the Xunta de Galicia (Spain). Consolidation 2020 GPC GI-1641 New Media (Trends, Cybermedia, Printed) - NEW MEDIA (2020-PG027). Ref. ED431B2020 / 20S