3,566 research outputs found
Public Quantum Communication and Superactivation
Is there a meaningful quantum counterpart to public communication? We argue
that the symmetric-side channel -- which distributes quantum information
symmetrically between the receiver and the environment -- is a good candidate
for a notion of public quantum communication in entanglement distillation and
quantum error correction.
This connection is partially motivated by [Brand\~ao and Oppenheim,
arXiv:1004.3328], where it was found that if a sender would like to communicate
a secret message to a receiver through an insecure quantum channel using a
shared quantum state as a key, then the insecure quantum channel is only ever
used to simulate a symmetric-side channel, and can always be replaced by it
without altering the optimal rate. Here we further show, in complete analogy to
the role of public classical communication, that assistance by a symmetric-side
channel makes equal the distillable entanglement, the recently-introduced
mutual independence, and a generalization of the latter, which quantifies the
extent to which one of the parties can perform quantum privacy amplification.
Symmetric-side channels, and the closely related erasure channel, have been
recently harnessed to provide examples of superactivation of the quantum
channel capacity. Our findings give new insight into this non-additivity of the
channel capacity and its relation to quantum privacy. In particular, we show
that single-copy superactivation protocols with the erasure channel, which
encompasses all examples of non-additivity of the quantum capacity found to
date, can be understood as a conversion of mutual independence into distillable
entanglement.Comment: 10 page
(Quantumness in the context of) Resource Theories
We review the basic idea behind resource theories, where we quantify quantum
resources by specifying a restricted class of operations. This divides the
state space into various sets, including states which are free (because they
can be created under the class of operations), and those which are a resource
(because they cannot be). One can quantify the worth of the resource by the
relative entropy distance to the set of free states, and under certain
conditions, this is a unique measure which quantifies the rate of state to
state transitions. The framework includes entanglement, asymmetry and purity
theory. It also includes thermodynamics, which is a hybrid resource theory
combining purity theory and asymmetry. Another hybrid resource theory which
merges purity theory and entanglement can be used to study quantumness of
correlations and discord, and we present quantumness in this more general
framework of resource theories.Comment: review articl
When does noise increase the quantum capacity?
Superactivation is the property that two channels with zero quantum capacity
can be used together to yield positive capacity. Here we demonstrate that this
effect exists for a wide class of inequivalent channels, none of which can
simulate each other. We also consider the case where one of two zero capacity
channels are applied, but the sender is ignorant of which one is applied. We
find examples where the greater the entropy of mixing of the channels, the
greater the lower bound for the capacity. Finally, we show that the effect of
superactivation is rather generic by providing example of superactivation using
the depolarizing channel.Comment: Corrected minor typo
Pharmaceutically modified subtilisins withstand acidic conditions and effectively degrade gluten in vivo
Detoxification of gluten immunogenic epitopes is a promising strategy for the treatment of celiac disease. Our previous studies have shown that these epitopes can be degraded in vitro by subtilisin enzymes derived from Rothia mucilaginosa, a natural microbial colonizer of the oral cavity. The challenge is that the enzyme is not optimally active under acidic conditions as encountered in the stomach. We therefore aimed to protect and maintain subtilisin-A enzyme activity by exploring two pharmaceutical modification techniques: PEGylation and Polylactic glycolic acid (PLGA) microencapsulation. PEGylation of subtilisin-A (Sub-A) was performed by attaching methoxypolyethylene glycol (mPEG, 5 kDa). The PEGylation protected subtilisin-A from autolysis at neutral pH. The PEGylated Sub-A (Sub-A-mPEG) was further encapsulated by PLGA. The microencapsulated Sub-A-mPEG-PLGA showed significantly increased protection against acid exposure in vitro. In vivo, gluten immunogenic epitopes were decreased by 60% in the stomach of mice fed with chow containing Sub-A-mPEG-PLGA (0.2mg Sub-A/ g chow) (n=9) compared to 31.9 % in mice fed with chow containing unmodified Sub-A (n=9). These results show that the developed pharmaceutical modification can protect Sub-A from auto-digestion as well as from acid inactivation, thus rendering the enzyme more effective for applications in vivo.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6522598/Published versio
Statistical Communication Theory
Contains reports on one completed research project and one current research project.Joint Services Electronics Programs (U.S. Army, U.S. Navy, and U.S. Air Force) under Contract DA 28-043-AMC-02536(E)National Aeronautics and Space Administration (Grant NsG-496
Tunable Vibrational Band Gaps in One-Dimensional Diatomic Granular Crystals with Three-Particle Unit Cells
We investigate the tunable vibration filtering properties of one-dimensional
diatomic granular crystals composed of arrays of stainless steel spheres and
cylinders interacting via Hertzian contact. The arrays consist of periodically
repeated three-particle unit cells (steel-cylinder-sphere) in which the length
of the cylinder is varied systematically. We apply static compression to
linearize the dynamic response of the crystals and characterize their linear
frequency spectrum. We find good agreement between theoretical dispersion
relation analysis (for infinite systems), state-space analysis (for finite
systems), and experiments. We report the observation of up to three distinct
pass bands and two finite band gaps and show their tunability for variations in
cylinder length and static compression
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