1,082 research outputs found
Towards quantum superpositions of a mirror
We propose a scheme for creating quantum superposition states involving of
order atoms via the interaction of a single photon with a tiny
mirror. This mirror, mounted on a high-quality mechanical oscillator, is part
of a high-finesse optical cavity which forms one arm of a Michelson
interferometer. By observing the interference of the photon only, one can study
the creation and decoherence of superpositions involving the mirror. All
experimental requirements appear to be within reach of current technology.Comment: 5 pages, 2 figures, submitted to Phys. Rev. Let
Quantum filter for non-local polarization properties of photonic qubits
We present an optical filter that transmits photon pairs only if they share
the same horizontal or vertical polarization, without decreasing the quantum
coherence between these two possibilities. Various applications for
entanglement manipulations and multi-photon qubits are discussed.Comment: 7 pages, including one figure, short discussion of error sources
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A posteriori teleportation
The article by Bouwmeester et al. on experimental quantum teleportation
constitutes an important advance in the burgeoning field of quantum
information. The experiment was motivated by the proposal of Bennett et al. in
which an unknown quantum state is `teleported' by Alice to Bob. As illustrated
in Fig. 1, in the implementation of this procedure, by Bouwmeester et al., an
input quantum state is `disembodied' into quantum and classical components, as
in the original protocol. However, in contrast to the original scheme,
Bouwmeester et al.'s procedure necessarily destroys the state at Bob's
receiving terminal, so a `teleported' state can never emerge as a freely
propagating state for subsequent examination or exploitation. In fact,
teleportation is achieved only as a postdiction.Comment: 1 page LaTeX including 1 figure. Scientific Correspondence about:
"Experimental quantum teleportation" Nature 390, 575 (1997
Entangled photons from the polariton vacuum in a switchable optical cavity
We study theoretically the entanglement of two-photon states in the ground
state of the intersubband cavity system, the so-called polariton vacuum. The
system consists of a sequence of doped quantum wells located inside a
microcavity and the photons can interact with intersubband excitations inside
the quantum wells. Using an explicit solution for the ground state of the
system, operated in the ultrastrong coupling regime, a post-selection is
introduced, where only certain two-photon states are considered and analyzed
for mode entanglement. We find that a fast quench of the coupling creates
entangled photons and that the degree of entanglement depends on the absolute
values of the in-plane wave vectors of the photons. Maximally entangled states
can be generated by choosing the appropriate modes in the post-selection.Comment: 9+ pages, 7 figure
Demonstration of Non-Deterministic Quantum Logic Operations using Linear Optical Elements
Knill, Laflamme, and Milburn recently showed that non-deterministic quantum
logic operations could be performed using linear optical elements, additional
photons (ancilla), and post-selection based on the output of single-photon
detectors [Nature 409, 46 (2001)]. Here we report the experimental
demonstration of two logic devices of this kind, a destructive controlled-NOT
(CNOT) gate and a quantum parity check. These two devices can be combined with
a pair of entangled photons to implement a conventional (non-destructive) CNOT
that succeeds with a probability of 1/4.Comment: 4 pages, 5 figures; Minor change
Interference due to Coherence Swapping
We propose a method called `coherence swapping' which enables us to create
superposition of a particle in two distinct paths, which is fed with initially
incoherent, independent radiations. This phenomenon is also present for the
charged particles, and can be used to swap the effect of flux line due to
Aharonov-Bohm effect. We propose an optical version of the experimental set-up
to test the coherence swapping. The phenomenon, which is simpler than
entanglement swapping or teleportation, raises some fundamental questions about
true nature of wave-particle duality, and also opens up the possibility of
studying the quantum erasure from a new angle.Comment: Latex file, 10 pages, Two figure
Linear optical implementation of a single mode quantum filter and generation of multi-photon polarization entangled state
We propose a scheme to implement a single-mode quantum filter, which
selectively eliminates the one-photon state in a quantum state
. The vacuum state and the two photon state are
transmitted without any change. This scheme requires single-photon sources,
linear optical elements and photon detectors. Furthermore we demonstrate, how
this filter can be used to realize a two-qubit projective measurement and to
generate multi-photon polarization entangled states.Comment: revision submitted to PR
Characterization of maize root microbiome in two different soils by minimizing plant DNA contamination in metabarcoding analysis
Strong coupling between single photons in semiconductor microcavities
We discuss the observability of strong coupling between single photons in
semiconductor microcavities coupled by a chi(2) nonlinearity. We present two
schemes and analyze the feasibility of their practical implementation in three
systems: photonic crystal defects, micropillars and microdisks, fabricated out
of GaAs. We show that if a weak coherent state is used to enhance the chi(2)
interaction, the strong coupling regime between two modes at different
frequencies occupied by a single photon is within reach of current technology.
The unstimulated strong coupling of a single photon and a photon pair is very
challenging and will require an improvement in mirocavity quality factors of
2-4 orders of magnitude to be observable.Comment: 4 page
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