Mean-field vs. quantum decoherence of ⁷Li matter-wave breathers

N-soliton breathers are high-order soliton solutions of the attractive nonlinear Schroedinger equation (NLSE). They may be formed by suddenly quenching the interaction strength of a fundamental soliton by certain integer factors.^1,2 The required control of the interaction strength is provided by a Feshbach resonance in a Bose-Einstein condensate of ⁷Li confined in quasi-1D. As mean-field (MF) solutions of an integrable equation, pure 1D breathers are localized in space and oscillate in time without dispersion. In reality, breathers are susceptible to decoherence due to both MF³ and quantum^4,5 effects. In this experiment, we report the MF decoherence of 2-soliton breathers due to three-body recombination. These findings impose an experimental limit on the atom density below which quantum effects can be observed. We present results of our efforts to observe decoherence due to quantum fluctuations of the relative parameters of 2-soliton breathers.⁶

1 A. Di Carli et al., Phys. Rev. Lett. 123, 123602 (2019)

2 D. Luo et al., Phys. Rev. Lett. 125, 183902 (2020)

3 N. Pereira and F. Chu, Phys. Fluids 22, 874 (1979)

4 B. Opanchuk and P.D. Drummond, Phys. Rev. A. 96, 053628 (2017)

5 O.V. Marchukov et al., Phys. Rev. Lett. 125, 050405 (2020)

6 S. Datta, V. Dunjko, and M. Olshanii, Physics 4, 12 (2022)