17-22 July 2022
Royal Conservatory of Music, Toronto
America/Toronto timezone

Emergent Spin Dynamics in a Superradiant Quantum Gas: From dynamical tunnelling to atomic mode parametric amplifiers

18 Jul 2022, 17:00
1h 30m
Hart House (Hart House)

Hart House

Hart House

7 Hart House Cir, Toronto, ON M5S 3H3
Poster presentation Degenerate gases, many-body physics, and quantum simulation Poster session


Dynamic transients are a natural ingredient of out-of-equilibrium quantum systems. One paradigmatic example is Dicke superradiance, describing the collectively enhanced population inversion of an ensemble of two-level atoms coupled to a single mode of the electromagnetic field.

Here, we present a new approach exploiting superradiance to engineer dynamical tunneling in a synthetic lattice geometry. Our experimental implementation is based on a spinor Bose-Einstein condensate (BEC), which is coupled to a single mode of an ultrahigh-finesse optical cavity [1]. Transverse laser fields induce cavity-assisted Raman transitions between discrete momentum modes of two spin levels, which we interpret as photon-assisted tunnelling in a momentum-space lattice. In particular, the tunnelling rate evolves dynamically with the emergent cavity field. By monitoring the cavity leakage, we gain real-time access to the lattice currents and benchmark their collective behaviour [2].

In a series of recent experiments, we engineer an atomic mode parametric amplifier induced by virtual cavity photons. The spinor BEC is initialized in the |F = 1, mF = 0⟩ Zeeman sublevel (pump mode), and correlated pairs of atoms in |mF = ±1⟩ (signal and idler modes) are created by four-photon processes, which involve scattering of virtual cavity photons in a far-detuned regime. The pair production is highly non-linear, as evidenced by its scaling with atom number. Moreover, the spin pairs are ejected out of the BEC with opposite relative momenta, in resemblance parametric four-wave mixing. While similar to collisional spin-mixing dynamics [3], the timescales of this process (~10 μs) are significantly faster, providing prospects rapid entanglement production in cold atom experiments.

[1] F. Ferri, R. Rosa-Medina, F. Finger, N. Dogra, M. Soriente, O. Zilberberg, T. Donner, T. Esslinger,
(2021). Emerging dissipative phases in a superradiant quantum gas with tunable decay. Physical Review X, 11(4), 041046.

[2] R. Rosa-Medina, F. Ferri, F. Finger, N. Dogra, K. Kroeger, R. Lin, R. Chitra, T. Donner,
T. Esslinger, (2022). Observing dynamical currents in a non-Hermitian momentum lattice. Physical Review Letters, 128(14), 143602.

[3] L. Pezze, A. Smerzi, M.K. Oberthaler, R. Schmied, P.Treutlein, (2018). Quantum metrology with nonclassical states of atomic ensembles. Reviews of Modern Physics, 90(3), 035005.

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Presenter name Rodrigo Rosa-Medina

Primary authors

Mr Rodrigo Rosa-Medina (ETH Zurich) Mr Fabian Finger (ETH Zurich) Mrs Nicola Reiter (ETH Zurich) Dr Francesco Ferri (ETH Zurich) Dr Tobias Donner (ETH Zurich) Prof. Tilman Esslinger (ETH Zurich)

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