1,807 research outputs found
Entanglement fluctuation theorems
Pure state entanglement transformations have been thought of as irreversible,
with reversible transformations generally only possible in the limit of many
copies. Here, we show that reversible entanglement transformations do not
require processing on the many copy level, but can instead be undertaken on
individual systems, provided the amount of entanglement which is produced or
consumed is allowed to fluctuate. We derive necessary and sufficient conditions
for entanglement manipulations in this case. As a corollary, we derive an
equation which quantifies the fluctuations of entanglement, which is formally
identical to the Jarzynski fluctuation equality found in thermodynamics. One
can also relate a forward entanglement transformation to its reverse process in
terms of the entanglement cost of such a transformation, in a manner equivalent
to the Crooks relation. We show that a strong converse theorem for entanglement
transformations is formally related to the second law of thermodynamics, while
the fact that the Schmidt rank of an entangled state cannot increase is related
to the third law of thermodynamics. Achievability of the protocols is done by
introducing an entanglement battery, a device which stores entanglement and
uses an amount of entanglement that is allowed to fluctuate but with an average
cost which is still optimal. This allows us to also solve the problem of
partial entanglement recovery, and in fact, we show that entanglement is fully
recovered. Allowing the amount of consumed entanglement to fluctuate also leads
to improved and optimal entanglement dilution protocols.Comment: comments welcome, v2 published versio
The second law of quantum thermodynamics as an equality
We investigate the connection between recent results in quantum
thermodynamics and fluctuation relations by adopting a fully quantum mechanical
description of thermodynamics. By including a work system whose energy is
allowed to fluctuate, we derive a set of equalities which all thermodynamical
transitions have to satisfy. This extends the condition for maps to be
Gibbs-preserving to the case of fluctuating work, providing a more general
characterisation of maps commonly used in the information theoretic approach to
thermodynamics. For final states, block diagonal in the energy basis, this set
of equalities are necessary and sufficient conditions for a thermodynamical
state transition to be possible. The conditions serves as a parent equation
which can be used to derive a number of results. These include writing the
second law of thermodynamics as an equality featuring a fine-grained notion of
the free energy. It also yields a generalisation of the Jarzynski fluctuation
theorem which holds for arbitrary initial states, and under the most general
manipulations allowed by the laws of quantum mechanics. Furthermore, we show
that each of these relations can be seen as the quasi-classical limit of three
fully quantum identities. This allows us to consider the free energy as an
operator, and allows one to obtain more general and fully quantum fluctuation
relations from the information theoretic approach to quantum thermodynamics.Comment: 11+3 pages. V4: Updated to match published version. Discussion of
thermo-majorization and implementing arbitary unitaries added. V3: Added
funding information. V2: Expanded discussion on relation to fluctuation
theorem
Electropermeabilization of inner and outer cell membranes with microsecond pulsed electric field. Quantitative study with calcium ions
Microsecond pulsed electric fields (mu sPEF) permeabilize the plasma membrane (PM) and are widely used in research, medicine and biotechnology. For internal membranes permeabilization, nanosecond pulsed electric fields (nsPEF) are applied but this technology is complex to use. Here we report that the endoplasmic reticulum (ER) membrane can also be electropermeabilized by one 100 mu s pulse without affecting the cell viability. Indeed, using Ca2+ as a permeabilization marker, we observed cytosolic Ca2+ peaks in two different cell types after one 100 mu s pulse in a medium without Ca2+. Thapsigargin abolished these Ca2+ peaks demonstrating that the calcium is released from the ER. Moreover, IP3R and RyR inhibitors did not modify these peaks showing that they are due to the electropermeabilization of the ER membrane and not to ER Ca2+ channels activation. Finally, the comparison of the two cell types suggests that the PM and the ER permeabilization thresholds are affected by the sizes of the cell and the ER. In conclusion, this study demonstrates that mu sPEF, which are easier to control than nsPEF, can permeabilize internal membranes. Besides, mu sPEF interaction with either the PM or ER, can be an efficient tool to modulate the cytosolic calcium concentration and study Ca2+ roles in cell physiology
2-NBDG, a Fluorescent Analogue of Glucose, as a Marker for Detecting Cell Electropermeabilization In Vitro
Abstract This study investigated whether molecules
spontaneously transported inside cells, like glucose derivatives,
can also be used as electropermeabilization markers.
Uptake of a fluorescent deoxyglucose derivative (2-NBDG)
by normal and electropermeabilized cells in culture was
analyzed. 2-NBDG was added to DC-3F cell suspensions
and cells, exposed or not to eight square-wave electric
pulses of 100-ls duration and of appropriate field amplitude
at a repetition frequency of 1 Hz or 5 kHz, were
incubated at 37 C. 2-NBDG uptake was temperature-,
concentration- and time-dependent in cells submitted or not
to the electric pulses. In spite of significant uptake of
2-NBDG mediated by GLUT transporters into nonpermeabilized
cells, the electric pulses significantly increased
about ten to hundred times the 2-NBDG uptake into the
cells. The increase in the field amplitude from 900 to
1,500 V/cm resulted in a progressive increase of 2-NDBG.
Our results show that under the conditions of in vivo
exposure duration to FDG and the physiological concentration
of D-glucose, electric pulses increased 2-NBDG
uptake into electropermeabilized cells. Under our experimental
conditions, the percentage of permeabilized cells
within the population of cells exposed to electric pulses
remained at the same level regardless of the pulse frequency
used, 1 Hz or 5 kHz. The findings showed that
glucose derivatives can also be used to detect electropermeabilized
cells exposed to electric pulses
Equivalence between two-qubit entanglement and secure key distribution
We study the problem of secret key distillation from bipartite states in the
scenario where Alice and Bob can only perform measurements at the single-copy
level and classically process the obtained outcomes. Even with these
limitations, secret bits can be asymptotically distilled by the honest parties
from any two-qubit entangled state, under any individual attack. Our results
point out a complete equivalence between two-qubit entanglement and secure key
distribution: a key can be established through a one-qubit channel if and only
if it allows to distribute entanglement. These results can be generalized to
higher dimension for all those states that are one-copy distillable.Comment: 5 pages, REVTEX. Accepted version + added appendix. Proof of the main
result and discussion improved, conclusions unchange
Beyond volutrauma in ARDS: the critical role of lung tissue deformation
Ventilator-induced lung injury (VILI) consists of tissue damage and a biological response resulting from the application of inappropriate mechanical forces to the lung parenchyma. The current paradigm attributes VILI to overstretching due to very high-volume ventilation (volutrauma) and cyclic changes in aeration due to very low-volume ventilation (atelectrauma); however, this model cannot explain some research findings. In the present review, we discuss the relevance of cyclic deformation of lung tissue as the main determinant of VILI. Parenchymal stability resulting from the interplay of respiratory parameters such as tidal volume, positive end-expiratory pressure or respiratory rate can explain the results of different clinical trials and experimental studies that do not fit with the classic volutrauma/atelectrauma model. Focusing on tissue deformation could lead to new bedside monitoring and ventilatory strategies
Technological and theoretical aspects for testing electroporation on liposomes
Recently, the use of nanometer liposomes as nanocarriers in drug delivery systems mediated by nanoelectroporation has been proposed. This technique takes advantage of the possibility of simultaneously electroporating liposomes and cell membrane with 10-nanosecond pulsed electric fields (nsPEF) facilitating the release of the drug from the liposomes and at the same time its uptake by the cells. In this paper the design and characterization of a 10 nsPEF exposure system is presented, for liposomes electroporation purposes. The design and the characterization of the applicator have been carried out choosing an electroporation cuvette with 1 mm gap between the electrodes. The structure efficiency has been evaluated at different experimental conditions by changing the solution conductivity from 0.25 to 1.6 S/m. With the aim to analyze the influence of device performances on the liposomes electroporation, microdosimetric simulations have been performed considering liposomes of 200 and 400 nm of dimension with different inner and outer conductivity (from 0.05 to 1.6 S/m) in order to identify the voltage needed for their poration
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