Rodrigo Felipe Rosa-Medina Pimentel


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Rosa-Medina Pimentel

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Rodrigo Felipe

ORCID

0000-0001-7321-7743

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2021 - 20248
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Publications 1 - 8 of 8
  • Quantum Fluctuation Dynamics of Dispersive Superradiant Pulses in a Hybrid Light-Matter System
    Item type: Journal Article
    Stitely, Kevin C.; Finger, Fabian; Rosa-Medina Pimentel, Rodrigo Felipe; et al. (2023)
    Physical Review Letters
    We consider theoretically a driven-dissipative quantum many-body system consisting of an atomic ensemble in a single-mode optical cavity as described by the open Tavis-Cummings model. In this hybrid light-matter system, the interplay between coherent and dissipative processes leads to superradiant pulses with a buildup of strong correlations, even for systems comprising hundreds to thousands of particles. A central feature of the mean-field dynamics is a self-reversal of two spin degrees of freedom due to an underlying time-reversal symmetry, which is broken by quantum fluctuations. We demonstrate a quench protocol that can maintain highly non-Gaussian states over long timescales. This general mechanism offers interesting possibilities for the generation and control of complex fluctuation patterns, as suggested for the improvement of quantum sensing protocols for dissipative spin amplification.
  • Emerging Dissipative Phases in a Superradiant Quantum Gas with Tunable Decay
    Item type: Journal Article
    Ferri, Francesco; Rosa-Medina Pimentel, Rodrigo Felipe; Finger, Fabian; et al. (2021)
    Physical Review X
    Exposing a many-body system to external drives and losses can transform the nature of its phases and opens perspectives for engineering new properties of matter. How such characteristics are related to the underlying microscopic processes of the driven and dissipative system is a fundamental question. Here, we address this point in a quantum gas that is strongly coupled to a lossy optical cavity mode using two independent Raman drives, which act on the spin and motional degrees of freedom of the atoms. This setting allows us to control the competition between coherent dynamics and dissipation by adjusting the imbalance between the drives. For strong enough coupling, the transition to a superradiant phase occurs, as is the case for a closed system. Yet, by imbalancing the drives, we can enter a dissipation-stabilized normal phase and a region of multistability. Measuring the properties of excitations on top of the out-ofequilibrium phases reveals the microscopic elementary processes in the open system. Our findings provide prospects for studying squeezing in non-Hermitian systems, quantum jumps in superradiance, and dynamical spin-orbit coupling in a dissipative setting.
  • Dynamics of spin-momentum entanglement from superradiant phase transitions
    Item type: Journal Article
    Chelpanova, Oksana; Seetharam, Kushal; Rosa-Medina Pimentel, Rodrigo Felipe; et al. (2024)
    Physical Review Research
    Exploring operational regimes of many-body cavity QED with multilevel atoms remains an exciting research frontier for their enhanced storage capabilities of intralevel quantum correlations. In this work, we consider an experimentally feasible many-body cavity QED model describing a four-level system, where each of those levels is formed from a combination of different spin and momentum states of ultracold atoms in a cavity. The resulting model comprises a pair of Dicke Hamiltonians constructed from pseudospin operators, effectively capturing two intertwined superradiant phase transitions. The phase diagram reveals regions featuring weak and strong entangled states of spin and momentum atomic degrees of freedom. These states exhibit different dynamical responses, ranging from slow to fast relaxation, with the added option of persistent entanglement temporal oscillations. We discuss the role of cavity losses in steering the system's dynamics into such entangled states and propose a readout scheme that leverages different light polarizations within the cavity. Our work paves the way to connect the rich variety of non-equilibrium phase transitions that occur in many-body cavity QED to the buildup of quantum correlations in systems with multilevel atom descriptions.
  • Phases, instabilities and excitations in a two-component lattice model with photon-mediated interactions
    Item type: Journal Article
    Carl, Leon; Rosa-Medina Pimentel, Rodrigo Felipe; Huber, Sebastian; et al. (2023)
    Physical Review Research
    Engineering long-range interacting spin systems with ultracold atoms offers the possibility to explore exotic magnetically ordered phases in strongly-correlated scenarios. Quantum gases in optical cavities provide a versatile experimental platform to further engineer photon-mediated interactions and access the underlying microscopic processes by probing the cavity field. Here, we study a two-component spin Bose-Hubbard system with cavity-mediated interactions. We provide a comprehensive overview of its phase diagram and transitions in experimentally relevant regimes. The interplay of different energy scales yields a rich phase diagram with superfluid and insulating phases exhibiting density modulation or spin ordering. In particular, the combined effect of contact and global-range interactions gives rise to an antiferromagnetically ordered phase for arbitrarily small spin-dependent light-matter coupling, while global-range and inter-spin contact interactions introduce regions of instability and phase separation in the phase diagram. We further study the low energy excitations above the antiferromagnetic phase. Besides particle-hole branches, it hosts spin-exchange excitations with a tunable energy gap. The studied lattice model can be readily realized in cold-atom experiments with optical cavities.
  • Spin- and Momentum-Correlated Atom Pairs Mediated by Photon Exchange and Seeded by Vacuum Fluctuations
    Item type: Journal Article
    Finger, Fabian; Rosa-Medina Pimentel, Rodrigo Felipe; Reiter, Nicola; et al. (2024)
    Physical Review Letters
    Engineering pairs of massive particles that are simultaneously correlated in their external and internal degrees of freedom is a major challenge, yet essential for advancing fundamental tests of physics and quantum technologies. In this Letter, we experimentally demonstrate a mechanism for generating pairs of atoms in well-defined spin and momentum modes. This mechanism couples atoms from a degenerate Bose gas via a superradiant photon-exchange process in an optical cavity, producing pairs via a single channel or two discernible channels. The scheme is independent of collisional interactions, fast, and tunable. We observe a collectively enhanced production of pairs and probe interspin correlations in momentum space. We characterize the emergent pair statistics and find that the observed dynamics is consistent with being primarily seeded by vacuum fluctuations in the corresponding atomic modes. Together with our observations of coherent many-body oscillations involving well-defined momentum modes, our results offer promising prospects for quantum-enhanced interferometry and quantum simulation experiments using entangled matter waves.
  • Exploring Dissipative and Coherent Spin Dynamics with Superradiant Quantum Gases
    Item type: Doctoral Thesis
    Rosa-Medina Pimentel, Rodrigo Felipe (2023)
    Experiments integrating ultracold quantum gases and optical cavities provide a versatile platform for exploring emergent collective phenomena, ranging from symmetry-breaking phase transitions to out-of-equilibrium many-body dynamics. In this thesis, we report on a series of experiments employing a Rb-87 Bose-Einstein condensate (BEC) coupled to a high-finesse optical cavity, with the goal of investigating photon-mediated dissipative and coherent spin dynamics. In the dispersive regime of atom-light interactions, we engineer cavity-assisted Raman transitions that couple specific internal and external modes of a degenerate quantum gas. This gives rise to superradiant Raman scattering of cavity photons, a process that is collectively enhanced by the number of participating atoms. In a first project, we couple two internal and external modes to realize an extended Dicke model with tunable coherent and dissipative interactions. The system undergoes a superradiant phase transition featuring spin-changing self-organization of the atoms. We experimentally access a dissipation-stabilized phase and a discontinuous superradiant transition in an extended region of phase bistability. The underlying mechanism is a collective decay of the hybrid light-matter excitations, which we resolve in real time by probing the cavity spectrum. In a second set of experiments, we engineer dynamical tunneling in a synthetic lattice in momentum space. Collective hopping between discrete momentum modes of a two-component BEC is implemented via superradiant Raman scattering, resulting in directional lattice dynamics due to the inherent cavity losses. By performing frequency-resolved measurements of the leaking cavity field, we resolve the individual tunneling events both in real time and non-destructively. We further extend our observations to a regime exhibiting mutually stimulating hopping cascades. In a third project, we demonstrate a mechanism for generating correlated atom pairs in well-defined spin and momentum modes. The pairs are created within tens of microseconds following the exchange of virtual cavity photons. We report on the first observation of coherent pair oscillations involving momentum modes, and achieve independent optical control of unitary pair processes and competing dissipative superradiant scattering. By characterizing the pair statistics and momentum-space correlations, we reveal beyond mean-field features and show their correlated nature. Our results demonstrate a comprehensive approach for studying photon-mediated magnetic phenomena in quantum gases. Extending the implemented cavity-assisted spin interactions to Hubbard systems can facilitate experimental access to strongly correlated magnetic phases, as proposed and theoretically investigated in a dedicated project. Finally, the observed pair mechanism paves the way for quantum-enhanced matter-wave interferometry and quantum simulation experiments beyond conventional solid-state systems.
  • Dissipation-Engineered Family of Nearly Dark States in Many-Body Cavity-Atom Systems
    Item type: Journal Article
    Lin, Rui; Rosa-Medina Pimentel, Rodrigo Felipe; Ferri, Francesco; et al. (2022)
    Physical Review Letters
    Three-level atomic systems coupled to light have the capacity to host dark states. We study a system of V-shaped three-level atoms coherently coupled to the two quadratures of a dissipative cavity. The interplay between the atomic level structure and dissipation makes the phase diagram of the open system drastically different from the closed one. In particular, it leads to the stabilization of a continuous family of dark and nearly dark excited many-body states with inverted atomic populations as the steady states. The multistability of these states can be probed via their distinct fluctuations and excitation spectra, as well as the system’s Liouvillian dynamics which are highly sensitive to ramp protocols. Our model can be implemented experimentally by encoding the two higher-energy modes in orthogonal density-modulated states in a bosonic quantum gas. This implementation offers prospects for potential applications like the realization of quantum optical random walks and microscopy with subwavelength spatial resolution.
  • Observing dynamical currents in a non-Hermitian momentum lattice
    Item type: Journal Article
    Rosa-Medina Pimentel, Rodrigo Felipe; Ferri, Francesco; Finger, Fabian; et al. (2022)
    Physical Review Letters
    We report on the experimental realization and detection of dynamical currents in a spin-textured lattice in momentum space. Collective tunneling is implemented via cavity-assisted Raman scattering of photons by a spinor Bose-Einstein condensate into an optical cavity. The photon field inducing the tunneling processes is subject to cavity dissipation, resulting in effective directional dynamics in a non-Hermitian setting. We observe that the individual tunneling events are superradiant in nature and locally resolve them in the lattice by performing real-time, frequency-resolved measurements of the leaking cavity field. The results can be extended to a regime exhibiting a cascade of currents and simultaneous coherences between multiple lattice sites, where numerical simulations provide further understanding of the dynamics. Our observations showcase dynamical tunneling in momentum-space lattices and provide prospects to realize dynamical gauge fields in driven-dissipative settings.
Publications 1 - 8 of 8