Publications Carlos GONZALEZ-BALLESTERO

2023

Article

T. E. Agrenius Gustafsson, C. Gonzalez-Ballestero, P. Maurer, O. Romero-Isart Interaction Between an Optically Levitated Nanoparticle and Its Thermal Image: Internal Thermometry via Displacement Sensing, Phys. Rev. Lett. 130 93601 (2023-02-28), http://dx.doi.org/10.1103/PhysRevLett.130.093601 doi:10.1103/PhysRevLett.130.093601 (ID: 720881)

2022

Articles

K. Kustura, C. Gonzalez-Ballestero, A. de los Ríos Sommer, N. Meyer, R. Quidant, O. Romero-Isart Mechanical squeezing via unstable dynamics in a microcavity, Phys. Rev. Lett. 128 143601 (2022-04-06), http://dx.doi.org/10.1103/PhysRevLett.128.143601 doi:10.1103/PhysRevLett.128.143601 (ID: 720706)
C. Gonzalez-Ballestero, T. van der Sar, O. Romero-Isart Towards a quantum interface between spin waves and paramagnetic spin baths, Phys. Rev. B 105 75410 (2022-02-08), http://dx.doi.org/10.1103/PhysRevB.105.075410 doi:10.1103/PhysRevB.105.075410 (ID: 720549)

Preprints

Patrick Maurer, Carlos Gonzalez-Ballestero, Oriol Romero-Isart Quantum Theory of Light Interaction with a Dielectric Sphere: Towards 3D Ground-State Cooling, (2022-12-12), arXiv:2212.04838 arXiv:2212.04838 (ID: 720917)
Johannes Piotrowski, D. Windey, J. Vijayan, Carlos Gonzalez-Ballestero, A. de los Ríos Sommer, N. Meyer, R. Quidant, Oriol Romero-Isart, René Reimann, L. Novotny Simultaneous ground-state cooling of two mechanical modes of a levitated nanoparticle, (2022-09-30), arXiv:2209.15326 arXiv:2209.15326 (ID: 720894)
S. Casulleras-Guardia, S. Knauer, Qi Wang, Oriol Romero-Isart, A. Chumak, Carlos Gonzalez-Ballestero Generation of Spin-Wave Pulses by Inverse Design, (2022-09-14), arXiv:2209.06608 arXiv:2209.06608 (ID: 720878)
Carlos Gonzalez-Ballestero, Johanna Zielinska, Massimiliano Rossi, A. Militaru, M. Frimmer, L. Novotny, Patrick Maurer, Oriol Romero-Isart Suppressing Recoil Heating in Levitated Optomechanics using Squeezed Light, (2022-09-14), arXiv:2209.05858 arXiv:2209.05858 (ID: 720877)

2021

Articles

C. Gonzalez-Ballestero, M. Aspelmeyer, L. Novotny, R. Quidant, O. Romero-Isart Levitodynamics: Levitation and Control of Microscopic Objects in Vacuum, Science 374 eabg3027 (2021-10-07), http://dx.doi.org/10.1126/science.abg3027 doi:10.1126/science.abg3027 (ID: 720691)
P. Heidler, C. Schneider, K. Kustura, C. Gonzalez-Ballestero, O. Romero-Isart, G. Kirchmair Non-Markovian Effects of Two-Level Systems in a Niobium Coaxial Resonator with a Single-Photon Lifetime of 10 ms, Phys. Rev. Applied 16 34024 (2021-09-13), http://dx.doi.org/10.1103/PhysRevApplied.16.034024 doi:10.1103/PhysRevApplied.16.034024 (ID: 720630) Toggle Abstract
Understanding and mitigating loss channels due to two-level systems (TLS) is one of the main corner stones in the quest of realizing long photon lifetimes in superconducting quantum circuits. Typically, the TLS to which a circuit couples are modelled as a large bath without any coherence. Here we demonstrate that the coherence of TLS has to be considered to accurately describe the ring-down dynamics of a coaxial quarter-waver resonator with an internal quality factor of $0.5\times10^9$ at the single-photon level. The transient analysis reveals an effective non-markovian dynamics of the combined TLS and cavity system, which we can accurately fit by introducing a comprehensive TLS model. The fit returns relaxation times around $T_1=0.8\,\mathrm{\mu s}$ for a total of $N\approx 2 \times 10^{8}$ TLS with power-law distributed coupling strengths. Despite the short-lived TLS excitations, we observe long-term effects on the cavity decay due to coherent elastic scattering between the resonator field and the TLS. The presented method is applicable to various systems and allows for a simple characterization of TLS properties.
M. Rodà Llordés, C. Gonzalez-Ballestero, A. Rubio López, M. Martínez-Pérez, F. Luis, O. Romero-Isart Quantum Size Effects in the Magnetic Susceptibility of a Metallic Nanoparticle, Phys. Rev. B 104 L100407 (2021-09-10), http://dx.doi.org/10.1103/PhysRevB.104.L100407 doi:10.1103/PhysRevB.104.L100407 (ID: 720539)
K. Kustura, O. Romero-Isart, C. Gonzalez-Ballestero Effective quantum dynamics induced by a driven two-level system bath, Phys. Rev. A 103 53709 (2021-05-24), http://dx.doi.org/10.1103/PhysRevA.103.053709 doi:10.1103/PhysRevA.103.053709 (ID: 720563)
S. Casulleras, C. Gonzalez-Ballestero, P. Maurer, J. García-Ripoll, O. Romero-Isart Remote Individual Addressing of Quantum Emitters with Chirped Pulses, Phys. Rev. Lett. 126 103602 (2021-03-09), http://dx.doi.org/10.1103/PhysRevLett.126.103602 doi:10.1103/PhysRevLett.126.103602 (ID: 720486)

Preprint

P. Maurer, C. Gonzalez-Ballestero, O. Romero-Isart Quantum Electrodynamics with a Nonmoving Dielectric Sphere: Quantizing Mie Scattering, (2021-06-16), arXiv:2106.07975 arXiv:2106.07975 (ID: 720662)

2020

Articles

E. Sanchez Burillo, A. Gonzalez-Tudela, C. Gonzalez-Ballestero Theory of waveguide-QED with moving emitters, Phys. Rev. A 102 13726 (2020-07-28), http://dx.doi.org/10.1103/PhysRevA.102.013726 doi:10.1103/PhysRevA.102.013726 (ID: 720481)
D. Hümmer, R. Lampert, K. Kustura, P. Maurer, C. Gonzalez-Ballestero, O. Romero-Isart Acoustic and Optical Properties of a Fast Spinning Dielectric Nanoparticle, Phys. Rev. B 101 205416 (2020-05-13), http://dx.doi.org/10.1103/PhysRevB.101.205416 doi:10.1103/PhysRevB.101.205416 (ID: 720430)
J. Gieseler, A. Kabcenell, E. Rosenfeld, J. D. Schaefer, A. Safira, M. J. Schuetz, C. Gonzalez-Ballestero, C. C. Rusconi, O. Romero-Isart, M. Lukin Single-Spin Magnetomechanics with Levitated Micromagnets, Phys. Rev. Lett. 124 163604 (2020-04-24), http://dx.doi.org/10.1103/PhysRevLett.124.163604 doi:10.1103/PhysRevLett.124.163604 (ID: 720435)
C. Gonzalez-Ballestero, J. Gieseler, O. Romero-Isart Quantum Acoustomechanics with a Micromagnet, Phys. Rev. Lett. 124 93602 (2020-03-03), http://dx.doi.org/10.1103/PhysRevLett.124.093602 doi:10.1103/PhysRevLett.124.093602 (ID: 720321)
C. Gonzalez-Ballestero, D. Hümmer, J. Gieseler, O. Romero-Isart Theory of Quantum Acoustomagnonics and Acoustomechanics with a Micromagnet, Phys. Rev. B 101 125404 (2020-03-02), http://dx.doi.org/10.1103/PhysRevB.101.125404 doi:10.1103/PhysRevB.101.125404 (ID: 720431)

2019

Articles

C. Gonzalez-Ballestero, P. Maurer, D. Windey, L. Novotny, R. Reimann, O. Romero-Isart Theory for Cavity Cooling of Levitated Nanoparticles via Coherent Scattering: Master Equation Approach, Phys. Rev. A 100 13805 (2019-07-03), http://dx.doi.org/10.1103/PhysRevA.100.013805 doi:10.1103/PhysRevA.100.013805 (ID: 720143)
D. Windey, C. Gonzalez-Ballestero, P. Maurer, L. Novotny, O. Romero-Isart, R. Reimann Cavity-Based 3D Cooling of a Levitated Nanoparticle via Coherent Scattering, Phys. Rev. Lett. 122 123601 (2019-03-27), http://dx.doi.org/10.1103/PhysRevLett.122.123601 doi:10.1103/PhysRevLett.122.123601 (ID: 720109)

2018

Article

A. Rubio López, C. Gonzalez-Ballestero, O. Romero-Isart Internal Quantum Dynamics of a Nanoparticle in a Thermal Electromagnetic Field: a Minimal Model, Phys. Rev. B 98 155405 (2018-10-08), http://dx.doi.org/10.1103/PhysRevB.98.155405 doi:10.1103/PhysRevB.98.155405 (ID: 720040)

2017

Article

C. Gonzalez-Ballestero, F. A. Y. N. Schröder, A. Chin Uncovering nonperturbative dynamics of the biased sub-Ohmic spin-boson model with variational matrix product states, Phys. Rev. B 96 115427 (2017-09-15), http://dx.doi.org/10.1103/PhysRevB.96.115427 doi:10.1103/PhysRevB.96.115427 (ID: 719833) Toggle Abstract
We study the dynamics of the biased sub-Ohmic spin-boson model by means of a time-dependent variational matrix product state (TDVMPS) algorithm. The evolution of both the system and the environment is obtained in the weak- and the strong-coupling regimes, respectively characterized by damped spin oscillations and by a nonequilibrium process where the spin freezes near its initial state, which are explicitly shown to arise from a variety of reactive environmental quantum dynamics. We also explore the rich phenomenology of the intermediate-coupling case, a nonperturbative regime where the system shows a complex dynamical behavior, combining features of both the weakly and the strongly coupled case in a sequential, time-retarded fashion. Our work demonstrates the potential of TDVMPS methods for exploring otherwise elusive, nonperturbative regimes of complex open quantum systems, and points to the possibilities of exploiting the qualitative, real-time modification of quantum properties induced by nonequilibrium bath dynamics in ultrafast transient processes.

2016

Articles

C. Gonzalez-Ballestero, E. Moreno, F. J. García-Vidal, A. Gonzalez-Tudela Nonreciprocal few-photon routing schemes based on chiral waveguide-emitter couplings, Phys. Rev. A 94 63817 (2016-12-06), http://dx.doi.org/10.1103/PhysRevA.94.063817 doi:10.1103/PhysRevA.94.063817 (ID: 719899) Toggle Abstract
We demonstrate the possibility of designing efficient, nonreciprocal few-photon devices by exploiting the chiral coupling between two waveguide modes and a single quantum emitter. We show how this system can show nonreciprocal photon transport at the single-photon level by exploiting a single-photon routing mechanism. Afterwards, we also demonstrate how the fundamentally different two-photon response makes the system show a transistorlike behavior, where a first photon can open a transmission channel for a second incoming photon. The efficiency in both cases is shown to be large for feasible experimental implementations. Our results illustrate the potential of chiral waveguide-emitter couplings for applications in quantum circuitry.
C. Gonzalez-Ballestero, J. Feist, E. Gonzalo-Badia, E. Moreno, F. J. García-Vidal Uncoupled Dark States Can Inherit Polaritonic Properties, Phys. Rev. Lett. 117 156402 (2016-10-07), http://dx.doi.org/10.1103/PhysRevLett.117.156402 doi:10.1103/PhysRevLett.117.156402 (ID: 719898) Toggle Abstract
When a collection of quantum emitters interacts with an electromagnetic field, the whole system can enter into the collective strong coupling regime in which hybrid light-matter states, i.e., polaritons can be created. Only a small portion of excitations in the emitters are coupled to the light field, and there are many dark states that, in principle, retain their pure excitonic nature. Here we theoretically demonstrate that these dark states can have a delocalized character, which is inherent to polaritons, despite the fact that they do not have a photonic component. This unexpected behavior only appears when the electromagnetic field displays a discrete spectrum. In this case, when the main loss mechanism in the hybrid system stems from the radiative losses of the light field, dark states are even more efficient than polaritons in transferring excitations across the structure.

2015

Articles

C. Gonzalez-Ballestero, A. Gonzalez-Tudela, F. J. García-Vidal, E. Moreno Chiral route to spontaneous entanglement generation, Phys. Rev. B 92 155304 (2015-10-06), http://dx.doi.org/10.1103/PhysRevB.92.155304 doi:10.1103/PhysRevB.92.155304 (ID: 719897)
C. Gonzalez-Ballestero, J. Feist, E. Moreno, F. J. García-Vidal Harvesting excitons through plasmonic strong coupling, Phys. Rev. B 92 121402(R) (2015-09-08), http://dx.doi.org/10.1103/PhysRevB.92.121402 doi:10.1103/PhysRevB.92.121402 (ID: 719896) Toggle Abstract
Exciton harvesting is demonstrated in an ensemble of quantum emitters coupled to localized surface plasmons. When the interaction between emitters and the dipole mode of a metallic nanosphere reaches the strong-coupling regime, the exciton conductance is greatly increased. The spatial map of the conductance matches the plasmon field intensity profile, which indicates that transport properties can be tuned by adequately tailoring the field of the plasmonic resonance. Under strong coupling, we find that pure dephasing can have detrimental or beneficial effects on the conductance, depending on the effective number of participating emitters. Finally, we show that the exciton transport in the strong-coupling regime occurs on an ultrafast time scale given by the inverse Rabi splitting (10 fs), which is orders of magnitude faster than transport through direct hopping between the emitters.
E. Bermúdez-Ureña, C. Gonzalez-Ballestero, M. Geiselmann, R. Marty, I. P. Radko, T. Holmgaard, Y. Alaverdyan, E. Moreno, F. J. García-Vidal, S. I. Bozhevolnyi, R. Quidant Coupling of individual quantum emitters to channel plasmons, Nat. Commun. 6 7783 (2015-08-07), http://dx.doi.org/10.1038/ncomms8883 doi:10.1038/ncomms8883 (ID: 719895)

2014

Article

C. Gonzalez-Ballestero, E. Moreno, F. J. García-Vidal Generation, manipulation, and detection of two-qubit entanglement in waveguide QED, Phys. Rev. A 89 42328 (2014-04-28), http://dx.doi.org/10.1103/PhysRevA.89.042328 doi:10.1103/PhysRevA.89.042328 (ID: 719894) Toggle Abstract
We study the possibility of using guided photons to generate, control, and measure the entanglement of two qubits that is mediated by a one-dimensional waveguide. We show how entanglement can be generated both with single-photon and with two-photon wave packets. The introduction of a second photon allows for a manipulation of the entanglement between the qubits, and phenomena such as sudden death and revival of entanglement appear. Finally, we propose a procedure for entanglement detection via the scattering output of a single photon over a qubit state.

2013

Article

C. Gonzalez-Ballestero, F. J. García-Vidal, E. Moreno Non-Markovian effects in waveguide-mediated entanglement, New J. Phys. 15 73015 (2013-07-05), http://dx.doi.org/10.1088/1367-2630/15/7/073015 doi:10.1088/1367-2630/15/7/073015 (ID: 719893) Toggle Abstract
We study the generation and evolution of entanglement between two qubits coupled through one-dimensional waveguide modes. By using a complete quantum electrodynamical formalism we go beyond the Markovian approximation. The diagonalization of the Hamiltonian is carried out, and a set of quasi-localized eigenstates is found. We show that when the qubit–waveguide coupling is increased, the Markov approximation is no longer valid, and the generation of entanglement is worsened.

2012

Article

P. A. Huidobro, A. Y. Nikitin, C. Gonzalez-Ballestero, L. Martín-Moreno, F. J. García-Vidal Superradiance mediated by graphene surface plasmons, Phys. Rev. B 85 155438 (2012-04-20), http://dx.doi.org/10.1103/PhysRevB.85.155438 doi:10.1103/PhysRevB.85.155438 (ID: 719892) Toggle Abstract
We demonstrate that the interaction between two emitters can be controlled by means of the efficient excitation of surface plasmon modes in graphene. We consider graphene surface plasmons supported by either two-dimensional graphene sheets or one-dimensional graphene ribbons, showing in both cases that the coupling between the emitters can be strongly enhanced or suppressed. The super- and subradiant regimes are investigated in the reflection and transmission configurations. Importantly, the length scale of the coupling between emitters, which in vacuum is fixed by the free-space wavelength, is now determined by the wavelength of the graphene surface plasmons, which can be extremely short and can be tuned at will via a gate voltage.

2011

Article

C. Gonzalez-Ballestero, L. M. Robledo, G. F. Bertsch Numeric and symbolic evaluation of the pfaffian of general skew-symmetric matrices, Computer Phys. Com. 182 2213 (2011-10-04), http://dx.doi.org/10.1016/j.cpc.2011.04.025 doi:10.1016/j.cpc.2011.04.025 (ID: 719891) Toggle Abstract
Evaluation of pfaffians arises in a number of physics applications, and for some of them a direct method is preferable to using the determinantal formula. We discuss two methods for the numerical evaluation of pfaffians. The first is tridiagonalization based on Householder transformations. The main advantage of this method is its numerical stability that makes unnecessary the implementation of a pivoting strategy. The second method considered is based on Aitkenʼs block diagonalization formula. It yields to a kind of LU (similar to Choleskyʼs factorization) decomposition (under congruence) of arbitrary skew-symmetric matrices that is well suited both for the numeric and symbolic evaluations of the pfaffian. Fortran subroutines (FORTRAN 77 and 90) implementing both methods are given. We also provide simple implementations in Python and Mathematica for purpose of testing, or for exploratory studies of methods that make use of pfaffians.