Research ArticlePHYSICS

Coherent perfect absorption of nonlinear matter waves

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Science Advances  10 Aug 2018:
Vol. 4, no. 8, eaat6539
DOI: 10.1126/sciadv.aat6539
  • Fig. 1 Working principle of CPA.

    (A) Incident radiation enters an absorber from two sides with a wave vector q. Provided that the complex amplitudes aL and bR are chosen properly, no radiation is transmitted or reflected. (B) Experimental realization with a BEC in an optical lattice. The matter waves enter a lossy lattice site from both sides. The losses are realized with an electron beam, which removes the atoms. Because of the interactions between the atoms, the two incoming waves are nonlinear, while the absorption in the lossy site is linear. a.u., arbitrary units.

  • Fig. 2 CPA in a BEC residing in an optical lattice.

    At t = 0, the elimination of atoms from the lattice site n = 0 starts. (A and B) Time evolution of the lattice filling in the CPA regime [γ ≈ 125 s−1 (A)] and above the breaking point [γ ≈ 1000 s−1 (B)]. Experimental data are shown as red points, and the numerical simulations are shown in blue. For clarity, we only show the first 10 sites on one side of the system. In (A), the density remains uniform across the lattice, which is the signature of CPA. In (B), the density at the dissipative site drops off rapidly, and no CPA can be observed. (C and D) Corresponding images of the atomic distribution in the lattice after the sequence. (E) Integrated atomic density of (C) and (D). (F) Unwrapped radian argument arg ψn at t = 40 ms for the solution shown in (A) (green curve) and (B) (blue curve). For all panels, we have U/ = 2600 s−1, J/ = 229 s−1. The error bars in (A) and (B) indicate the statistical error, resulting from the summation over 50 experimental runs.

  • Fig. 3 Experimentally measured decay rate of the filling level.

    Up to a critical dissipation strength γexp ≈ 250 s−1 (black dashed line), the filling level remains constant (compare Fig. 2A), corresponding to the CPA regime. Above this value, the dissipation dominates the dynamics, and the filling level decays exponentially (compare Fig. 2B). The statistical error of the decay rate is smaller than the size of the points; however, we estimate a 5% systematic error due to technical imperfections such as drifts of the electron beam current. The error in the dissipation rate originates from the calibration measurement (see Materials and Methods).

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    • Fig. S1. Photograph of the vacuum chamber and sketch of the optical trapping scheme.

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