4 research outputs found
Observing the emergence of chaos in a many-particle quantum system
Accessing the connection between classical chaos and quantum many-body
systems has been a long-standing experimental challenge. Here, we investigate
the onset of chaos in periodically driven two-component Bose-Einstein
condensates, whose small quantum uncertainties allow for exploring the phase
space with high resolution. By analyzing the uncertainties of time-evolved
many-body states, we find signatures of elliptic and hyperbolic periodic orbits
generated according to the Poincar\'e-Birkhoff theorem, and the formation of a
chaotic region at increasing driving strengths. The employed fluctuation
analysis allows for probing the phase-space structure by use of only short-time
quantum dynamics.Comment: 5+2 pages, 4 figure
Single spontaneous photon as a coherent beamsplitter for an atomic matterwave
In spontaneous emission an atom in an excited state undergoes a transition to
the ground state and emits a single photon. Associated with the emission is a
change of the atomic momentum due to photon recoil. Photon emission can be
modified close to surfaces and in cavities. For an ion, localized in front of a
mirror, coherence of the emitted resonance fluorescence has been reported. In
free space experiments demonstrated that spontaneous emission destroys motional
coherence. Here we report on motional coherence created by a single spontaneous
emission event close to a mirror surface. The coherence in the free atomic
motion is verified by atom interferometry. The photon can be regarded as a
beamsplitter for an atomic matterwave and consequently our experiment extends
the original recoiling slit Gedanken experiment by Einstein to the case where
the slit is in a robust coherent superposition of the two recoils associated
with the two paths of the quanta.Comment: main text: 5 pages, 4 figure; supplementary information: 8 pages, 1
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