34 research outputs found
Quantum thermal machines with single nonequilibrium environments
We propose a scheme for a quantum thermal machine made by atoms interacting
with a single non-equilibrium electromagnetic field. The field is produced by a
simple configuration of macroscopic objects held at thermal equilibrium at
different temperatures. We show that these machines can deliver all
thermodynamic tasks (cooling, heating and population inversion), and this by
establishing quantum coherence with the body on which they act. Remarkably,
this system allows to reach efficiencies at maximum power very close to the
Carnot limit, much more than in existing models. Our findings offer a new
paradigm for efficient quantum energy flux management, and can be relevant for
both experimental and technological purposes.Comment: 10 pages, 6 figure
Thermally-activated non-local amplification in quantum energy transport
We study energy-transport efficiency in light-harvesting planar and 3D
complexes of two-level atomic quantum systems, embedded in a common thermal
blackbody radiation. We show that the collective non-local dissipation induced
by the thermal bath plays a fundamental role in energy transport. It gives rise
to a dramatic enhancement of the energy-transport efficiency, which may largely
overcome . This effect, which improves the understanding of transport
phenomena in experimentally relevant complexes, suggests a particularly
promising mechanism for quantum energy management.Comment: 7 pages, 4 figures. New version in which the RP line of Figure 1 has
been amended with the correct parameter
Heat capacity and entanglement
Starting from a recent result on thermodynamic equilibrium of quantum systems, a connection between thermal properties, originating from Gibbs state probabilistic structure, and quantum correlations is discussed as a consequence of entanglement monogamy. As an example, a simple two-qubit system is analyzed, allowing for an expression of such a connection as an explicit function linking heat capacity to a measure of bipartite entanglement
Distributed thermal tasks on many-body systems through a single quantum machine
We propose a configuration of a single three-level quantum emitter embedded
in a non-equilibrium steady electromagnetic environment, able to stabilize and
control the local temperatures of a target system it interacts with, consisting
of a collection of coupled two-level systems. The temperatures are induced by
dissipative processes only, without the need of further external couplings for
each qubit. Moreover, by acting on a set of easily tunable geometric
parameters, we demonstrate the possibility to manipulate and tune each qubit
temperature independently over a remarkably broad range of values. These
findings address one standard problem in quantum-scale thermodynamics,
providing a way to induce a desired distribution of temperature among
interacting qubits and to protect it from external noise sources.Comment: 6 pages, 5 figure
Fluctuation theorems for non-Markovian quantum processes
Exploiting previous results on Markovian dynamics and fluctuation theorems,
we study the consequences of memory effects on single realizations of
nonequilibrium processes within an open system approach. The entropy production
along single trajectories for forward and backward processes is obtained with
the help of a recently proposed classical-like non-Markovian stochastic
unravelling, which is demonstrated to lead to a correction of the standard
entropic fluctuation theorem. This correction is interpreted as resulting from
the interplay between the information extracted from the system through
measurements and the flow of information from the environment to the open
system: Due to memory effects single realizations of a dynamical process are no
longer independent, and their correlations fundamentally affect the behavior of
entropy fluctuations.Comment: 7 pages, 1 figur
Tomographic approach to the violation of Bell's inequalities for quantum states of two qutrits
The tomographic method is employed to investigate the presence of quantum
correlations in two classes of parameter-dependent states of two qutrits. The
violation of some Bell's inequalities in a wide domain of the parameter space
is shown. A comparison between the tomographic approach and a recent method
elaborated by Wu, Poulsen and Molmer shows the better adequacy of the former
method with respect to the latter one.Comment: 9 pages, 4 figure
Distributed correlations and information flows within a hybrid multipartite quantum-classical system
Understanding the non-Markovian mechanisms underlying the revivals of quantum
entanglement in the presence of classical environments is central in the theory
of quantum information. Tentative interpretations have been given by either the
role of the environment as a control device or the concept of hidden
entanglement. We address this issue from an information-theoretic point of
view. To this aim, we consider a paradigmatic tripartite system, already
realized in the laboratory, made of two independent qubits and a random
classical field locally interacting with one qubit alone. We study the
dynamical relationship between the two-qubit entanglement and the genuine
tripartite correlations of the overall system, finding that collapse and
revivals of entanglement correspond, respectively, to raise and fall of the
overall tripartite correlations. Interestingly, entanglement dark periods can
enable plateaux of nonzero tripartite correlations. We then explain this
behavior in terms of information flows among the different parties of the
system. Besides showcasing the phenomenon of the freezing of overall
correlations, our results provide new insights on the origin of retrieval of
entanglement within a hybrid quantum-classical system.Comment: 9 pages, 5 figures. To appear on Phys. Rev.
Estimation of Piecewise-Deterministic Trajectories in a Quantum Optics Scenario
International audienceThe manipulation of individual copies of quantum systems is one of the most groundbreaking experimental discoveries in the field of quantum physics. On both an experimental and a theoretical level, it has been shown that the dynamics of a single copy of an open quantum system is a trajectory of a piecewise-deterministic process. To the best of our knowledge, this application field has not been explored by the literature in applied mathematics, from both probabilistic and statistical perspectives. The objective of this chapter is to provide a self-contained presentation of this kind of model, as well as its specificities in terms of observations scheme of the system, and a first attempt to deal with a statistical issue that arises in the quantum world
Label-free approaches for extracellular vesicle detection
Extracellular vesicles (EVs) represent pivotal mediators in cell-to-cell communication. They are lipid-membranous carriers of several biomolecules, which can be produced by almost all cells. In the current Era of precision medicine, EVs gained growing attention thanks to their potential in both biomarker discovery and nanotherapeutics applications. However, current technical limitations in isolating and/or detecting EVs restrain their standard use in clinics. This review explores all the state-of-the-art analytical technologies which are currently overcoming these issues. On one end, several innovative optical-, electrical- and spectroscopy-based detection methods represent advantageous label-free methodologies for faster EV detection. On the other end, microfluidics-based lab-on-a-chip tools support EV purification from low-concentrated samples. Altogether, these technologies will strengthen the routine application of EVs in clinics