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Real-time detection of individual atoms falling through a high-finesse optical cavity
The enhanced coupling between atoms and photons inside a high-finesse optical cavity provides a novel basis for optical measurements that continuously monitor atomic degrees of freedom. We describe an experiment in which cavity quantum-electrodynamic effects are utilized for real-time detection of individual atoms falling through an optical cavity after being dropped from a magneto-optical trap. Our technique permits experiments that are triggered by the presence of a single optimally coupled atom within the cavity mode volume
Detecting Acceleration-Enhanced Vacuum Fluctuations with Atoms Inside a Cavity
Some of the most prominent theoretical predictions of modern times, e.g., the
Unruh effect, Hawking radiation, and gravity-assisted particle creation, are
supported by the fact that various quantum constructs like particle content and
vacuum fluctuations of a quantum field are observer-dependent. Despite being
fundamental in nature, these predictions have not yet been experimentally
verified because one needs extremely strong gravity (or acceleration) to bring
them within the existing experimental resolution. In this Letter, we
demonstrate that a post-Newtonian rotating atom inside a far-detuned cavity
experiences strongly modified quantum fluctuations in the inertial vacuum. As a
result, the emission rate of an excited atom gets enhanced significantly along
with a shift in the emission spectrum due to the change in the quantum
correlation under rotation. We propose an optomechanical setup that is capable
of realizing such acceleration-induced particle creation with current
technology. This provides a novel and potentially feasible experimental
proposal for the direct detection of noninertial quantum field theoretic
effects.Comment: Published in PR
Non-Markovianity and coherence of a moving qubit inside a leaky cavity
Non-Markovian features of a system evolution, stemming from memory effects,
may be utilized to transfer, storage, and revive basic quantum properties of
the system states. It is well known that an atom qubit undergoes non-Markovian
dynamics in high quality cavities. We here consider the qubit-cavity
interaction in the case when the qubit is in motion inside a leaky cavity. We
show that, owing to the inhibition of the decay rate, the coherence of the
traveling qubit remains closer to its initial value as time goes by compared to
that of a qubit at rest. We also demonstrate that quantum coherence is
preserved more efficiently for larger qubit velocities. This is true
independently of the evolution being Markovian or non-Markovian, albeit the
latter condition is more effective at a given value of velocity. We however
find that the degree of non-Markovianity is eventually weakened as the qubit
velocity increases, despite a better coherence maintenance.Comment: 16 pages and 5 figures. Written for the upcoming special volume "40
years of the GKLS equation", to be published in the journal Open Systems and
Information Dynamics. A co-author and some references adde
Cavity-assisted spontaneous emission as a single-photon source: Pulse shape and efficiency of one-photon Fock state preparation
Within the framework of exact quantum electrodynamics in dispersing and
absorbing media, we have studied the quantum state of the radiation emitted
from an initially in the upper state prepared two-level atom in a high-
cavity, including the regime where the emitted photon belongs to a wave packet
that simultaneously covers the areas inside and outside the cavity. For both
continuing atom--field interaction and short-term atom--field interaction, we
have determined the spatio-temporal shape of the excited outgoing wave packet
and calculated the efficiency of the wave packet to carry a one-photon Fock
state. Furthermore, we have made contact with quantum noise theories where the
intracavity field and the field outside the cavity are regarded as
approximately representing independent degrees of freedom such that two
separate Hilbert spaces can be introduced.Comment: 16 pages, 7 eps figures; improved version as submitted to Phys. Rev.
van der Waals coupling in atomically doped carbon nanotubes
We have investigated atom-nanotube van der Waals (vdW) coupling in atomically
doped carbon nanotubes (CNs). Our approach is based on the perturbation theory
for degenerated atomic levels, thus accounting for both weak and strong
atom-vacuum-field coupling. The vdW energy is described by an integral equation
represented in terms of the local photonic density of states (DOS). By solving
it numerically, we demonstrate the inapplicability of standard
weak-coupling-based vdW interaction models in a close vicinity of the CN
surface where the local photonic DOS effectively increases, giving rise to an
atom-field coupling enhancement. An inside encapsulation of atoms into the CN
has been shown to be energetically more favorable than their outside adsorption
by the CN surface. If the atom is fixed outside the CN, the modulus of the vdW
energy increases with the CN radius provided that the weak atom-field coupling
regime is realized (i.e., far enough from the CN). For inside atomic position,
the modulus of the vdW energy decreases with the CN radius, representing a
general effect of the effective interaction area reduction with lowering the CN
curvature.Comment: 15 pages, 5 figure
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