Publications (2023)

Quantum control of tunable-coupling transmons using dynamical invariants of motion

Authors: Espinos, H.; Panadero, I; Garcia-Ripoll, J. J.; Torrontegui, E.


Publication date: 2023/04/01

DOI: 10.1088/2058-9565/acbed7

Abstract: We analyze the implementation of a fast nonadiabatic CZ gate between two transmon qubits with tunable coupling. The gate control method is based on a theory of dynamical invariants which leads to reduced leakage and robustness against decoherence. The gate is based on a description of the resonance between the |11) and |20) using an effective Hamiltonian with the six lowest energy states. A modification of the protocol allows us […]

Parallel tomography of quantum non-demolition measurements in multi-qubit devices

Authors: Pereira, L.; Garcia-Ripoll, J. J.; Ramos, T.


Publication date: 2023/03/04

DOI: 10.1038/s41534-023-00688-7

Abstract: An efficient characterization of QND measurements is an important ingredient toward certifying and improving the performance and scalability of quantum processors. In this work, we introduce a parallel tomography of QND measurements that addresses single- and two-qubit readout on a multi-qubit quantum processor. We provide an experimental demonstration of the tomographic protocol on a 7-qubit IBM-Q device, characterizing the quality of conventional qubit readout as well as generalized measurements such as parity or […]

Vibrational, non-adiabatic and isotopic effects in the dynamics of the H-2 + H2?+H3+ + H reaction: application to plasma modelling

Authors: del Mazo-Sevillano, P.; Felix-Gonzalez, D.; Aguado, A.; Sanz-Sanz, C.; Kwon, D. -H.; Roncero, O.


Publication date: 2023/03/01

DOI: 10.1080/00268976.2023.2183071

Abstract: The title reaction is studied using a quasi-classical trajectory method for collision energies between 0.1 meV and 10 eV, considering the vibrational excitation of H-2(+) reactant. A new potential energy surface is developed based on a Neural Network many body correction of a triatomics-in-molecules potential, which significantly improves the accuracy of the potential up to energies of 17 eV, higher than in other previous fits. The effect […]

Gas kinematics around filamentary structures in the Orion B cloud

Authors: Gaudel, Mathilde; Orkisz, Jan H.; Gerin, Maryvonne; Pety, Jerome; Roueff, Antoine; Marchal, Antoine; Levrier, Francois; Miville-Deschenes, Marc-Antoine; Goicoechea, Javier R.; Roueff, Evelyne; Le Petit, Franck; Magalhaes, Victor de Souza; Palud, Pierre; Santa-Maria, Miriam G.; Vono, Maxime; Bardeau, Sebastien; Bron, Emeric; Chainais, Pierre; Chanussot, Jocelyn; Gratier, Pierre; Guzman, Viviana; Hughes, Annie; Kainulainen, Jouni; Languignon, David; Le Bourlot, Jacques; Liszt, Harvey; Oberg, Karin; Peretto, Nicolas; Sievers, Albrecht; Tremblin, Pascal


Publication date: 2023/02/07

DOI: 10.1051/0004-6361/202142109

Abstract: Context. Understanding the initial properties of star-forming material and how they affect the […]

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The stochastic wave function method for diffusion of alkali atoms on metallic surfaces

Authors: Torres-Miyares, E. E.; Ward, D. J.; Rojas-Lorenzo, G.; Rubayo-Soneira, J.; Allison, W.; Miret-Artes, S.


Publication date: 2023/02/05

DOI: 10.1039/d2cp05511b

Abstract: The stochastic wave function method is proposed to study the diffusion regimes of alkali atoms on metallic surfaces. The Lindblad approach, based on the microscopic Hamiltonian information in the Caldeira-Leggett model, is presented and numerical calculations of the dynamics are carried out to characterize surface diffusion for two different systems: Na-Cu(111) and Li-Cu(111). Calculations of the intermediate scattering function for an isolated adsorbate are compared, […]

Quantum Approximate Optimization Algorithm Pseudo-Boltzmann States

Authors: Diez-Valle, Pablo; Porras, Diego; Garcia-Ripoll, Juan Jose


Publication date: 2023/02/02

DOI: 10.1103/PhysRevLett.130.050601

Abstract: In this Letter, we provide analytical and numerical evidence that the single-layer quantum approximate optimization algorithm on universal Ising spin models produces thermal-like states. We find that these pseudo-Boltzmann states can not be efficiently simulated on classical computers according to the general state-of-the-art condition that ensures rapid mixing for Ising models. Moreover, we observe that the temperature depends on a hidden universal correlation between the energy of a state and the covariance of […]

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The Binary and the Disk: The Beauty is Found within NGC3132 with JWST

Authors: Sahai, Raghvendra; Bujarrabal, Valentin; Quintana-Lacaci, Guillermo; Reindl, Nicole; Van de Steene, Griet; Contreras, Carmen Sanchez; Ressler, Michael E.


Publication date: 2023/02/01

DOI: 10.3847/1538-4357/aca7ba

Abstract: The planetary nebula (PN) NGC 3132 is a striking example of the dramatic but poorly understood mass-loss phenomena that (1-8) M (circle dot) stars undergo during their death throes as they evolve into white dwarfs (WDs). From an analysis of JWST multiwavelength (0.9-18 mu m) imaging of NGC 3132, we report the discovery of an extended dust cloud around the WD central star […]

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History of two mass loss processes in VYCMa Fast outflows carving older ejecta

Authors: Quintana-Lacaci, G.; Velilla-Prieto, L.; Agundez, M.; Fonfria, J. P.; Cernicharo, J.; Decin, L.; Castro-Carrizo, A.


Publication date: 2023/01/05

DOI: 10.1051/0004-6361/202244396

Abstract: Context. Red supergiant stars (RSGs, M-init=10-40 M-circle dot) are known to eject large amounts of material, as much as half of their initial mass during this evolutionary phase. However, the processes powering the mass ejection in low- and intermediate-mass stars do not work for RSGs and the mechanism that drives the ejection remains unknown. Different mechanisms have been proposed as responsible for this mass ejection […]

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Discovery of interstellar NC4NH+: Dicyanopolyynes are indeed abundant in space

Authors: Agundez, M.; Cabezas, C.; Marcelino, N.; Fuentetaja, R.; Tercero, B.; de Vicente, P.; Cernicharo, J.


Publication date: 2023/01/01

DOI: 10.1051/0004-6361/202245492

Abstract: The previous detection of two species related to the nonpolar molecule cyanogen (NCCN), its protonated form (NCCNH+) and one metastable isomer (CNCN), in cold dense clouds supported the hypothesis that dicyanopolyynes are abundant in space. Here we report the first identification in space of NC4NH+. This cation is the protonated form of NC4N, which is the second member of the series of dicyanopolyynes after NCCN. […]

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