2 research outputs found
Dark solitons revealed in Lieb-Liniger eigenstates
We study how dark solitons, i.e. solutions of one-dimensional single-particle
nonlinear time-dependent Schr\"odinger equation, emerge from eigenstates of a
linear many-body model of contact interacting bosons moving on a ring, the
Lieb-Liniger model. This long-standing problem was addressed by various groups,
which presented different, seemingly unrelated, procedures to reveal the
solitonic waves directly from the many-body model. Here, we propose a
unification of these results using a simple Ansatz for the many-body eigenstate
of the Lieb-Liniger model, which gives us access to systems of hundreds of
atoms. In this approach, mean-field solitons emerge in a single-particle
density through repeated measurements of particle positions in the Ansatz
state. The post-measurement state turns out to be a wave packet of yrast states
of the reduced system.Comment: 8 pages of the main text + 7 pages of appendice
Phase diagram and optimal control for n-tupling discrete time crystal
A remarkable consequence of spontaneously breaking the time translational
symmetry in a system, is the emergence of time crystals. In periodically driven
systems, discrete time crystals (DTC) can be realized which have a periodicity
that is n times the driving period. However, all of the experimental
observations have been performed for period-doubling and period-tripling
discrete time crystals. Novel physics can arise by simulating many-body physics
in the time domain, which would require a genuine realisation of the n-tupling
DTC. A system of ultra-cold bosonic atoms bouncing resonantly on an oscillating
mirror is one of the models that can realise large period DTC. The preparation
of DTC demands control in creating the initial distribution of the ultra-cold
bosonic atoms along with the mirror frequency. In this work, we demonstrate
that such DTC is robust against perturbations to the initial distribution of
atoms. We show how Bayesian methods can be used to enhance control in the
preparation of the initial state as well as to efficiently calculate the phase
diagram for such a model. Moreover, we examine the stability of DTCs by
analyzing quantum many-body fluctuations and show that they do not reveal
signatures of heating.Comment: 21 pages, 5 figure