4,601 research outputs found
On-chip quantum tomography of mechanical nano-scale oscillators with guided Rydberg atoms
Nano-mechanical oscillators as well as Rydberg-atomic waveguides hosted on
micro-fabricated chip surfaces hold promise to become pillars of future quantum
technologies. In a hybrid platform with both, we show that beams of Rydberg
atoms in waveguides can quantum-coherently interrogate and manipulate
nanomechanical elements, allowing full quantum state tomography. Central to the
tomography are quantum non-demolition measurements using the Rydberg atoms as
probes. Quantum coherent displacement of the oscillator is also made possible,
by driving the atoms with external fields while they interact with the
oscillator. We numerically demonstrate the feasibility of this fully integrated
on-chip control and read-out suite for quantum nano-mechanics, taking into
account noise and error sources.Comment: 11 pages, 5 figures, 1 tabl
Conical intersections in an ultracold gas
We find that energy surfaces of more than two atoms or molecules interacting
via dipole-dipole po- tentials generically possess conical intersections (CIs).
Typically only few atoms participate strongly in such an intersection. For the
fundamental case, a circular trimer, we show how the CI affects adiabatic
excitation transport via electronic decoherence or geometric phase
interference. These phe- nomena may be experimentally accessible if the trimer
is realized by light alkali atoms in a ring trap, whose dipole-dipole
interactions are induced by off-resonant dressing with Rydberg states. Such a
setup promises a direct probe of the full many-body density dynamics near a
conical intersection.Comment: 4 pages, 4 figures, replacement to add archive referenc
Newton's cradle and entanglement transport in a flexible Rydberg chain
In a regular, flexible chain of Rydberg atoms, a single electronic excitation
localizes on two atoms that are in closer mutual proximity than all others. We
show how the interplay between excitonic and atomic motion causes electronic
excitation and diatomic proximity to propagate through the Rydberg chain as a
combined pulse. In this manner entanglement is transferred adiabatically along
the chain, reminiscent of momentum transfer in Newton's cradle.Comment: 4 pages, 3 figures. Revised versio
Excitation transport through Rydberg dressing
We show how to create long range interactions between alkali-atoms in
different hyper-fine ground states, allowing coherent electronic quantum state
migration. The scheme uses off resonant dressing with atomic Rydberg states,
exploiting the dipole-dipole excitation transfer that is possible between
those. Actual population in the Rydberg state is kept small. Dressing offers
large advantages over the direct use of Rydberg levels: It reduces ionisation
probabilities and provides an additional tuning parameter for life-times and
interaction-strengths. We present an effective Hamiltonian for the ground-state
manifold and show that it correctly describes the full multi-state dynamics for
up to 5 atoms.Comment: 22 pages + 6 pages appendices, 8 figures, replaced with revised
version, added journal referenc
Ionization and charge migration through strong internal fields in clusters exposed to intense X-ray pulses
A general scenario for electronic charge migration in finite samples
illuminated by an intense laser pulse is given. Microscopic calculations for
neon clusters under strong short pulses as produced by X-ray free-electron
laser sources confirm this scenario and point to the prominent role of field
ionization by strong internal fields. The latter leads to the fast formation of
a core-shell system with an almost static core of screened ions while the outer
shell explodes. Substituting the shell ions with a different material such as
helium as a sacrificial layer leads to a substantial improvement of the
diffraction image for the embedded cluster thus reducing the consequences of
radiation damage for coherent diffractive imaging.Comment: 5 pages, 4 figure
Dipole-dipole induced global motion of Rydberg-dressed atom clouds
We consider two clouds of ground state alkali atoms in two distinct hyperfine
ground states. Each level is far off-resonantly coupled to a Rydberg state,
which leads to dressed ground states with a weak admixture of the Rydberg state
properties. Due to this admixture, for a proper choice of the Rydberg states,
the atoms experience resonant dipole-dipole interactions that induce mechanical
forces acting on all atoms within both clouds. This behavior is in contrast to
the dynamics predicted for bare dipole-dipole interactions between Rydberg
superatoms, where only a single atom per cloud is subject to dipole-dipole
induced motion [Phys. Rev. A {\bf 88} 012716 (2013)].Comment: 15 pages, 2 figure
Source of entangled atom pairs on demand, using the Rydberg blockade
Two ultracold atom clouds, each separately in a dipole-blockade regime,
realize a source of entangled atom pairs that can be ejected on demand.
Entanglement generation and ejection is due to resonant dipole-dipole
interactions, while van-der-Waals interactions are predominantly responsible
for the blockade that ensures the ejection of a single atom per cloud. A source
of entangled atoms using these effects can operate with a 10 kHz repetition
rate producing ejected atoms with velocities of about 0.5 m/s.Comment: 7 pages, 4 figure
Model- and Parameteroptimization for a Constitutive Law Describing Deformation Induced Anisotropy
 
- …