4,022 research outputs found
Semi-device-independent characterization of quantum measurements under a minimum overlap assumption
Recently, a novel framework for semi-device-independent quantum
prepare-and-measure protocols has been proposed, based on the assumption of a
limited distinguishability between the prepared quantum states. Here, we
discuss the problem of characterizing an unknown quantum measurement device in
this setting. We present several methods to attack this problem. Considering
the simplest scenario of two preparations with lower bounded overlap, we show
that genuine 3-outcome POVMs can be certified, even in the presence of noise.
Moreover, we show that the optimal POVM for performing unambiguous state
discrimination can be self-tested.Comment: 9 pages,7 figure
Physical implementations of quantum absorption refrigerators
Absorption refrigerators are autonomous thermal machines that harness the
spontaneous flow of heat from a hot bath into the environment in order to
perform cooling. Here we discuss quantum realizations of absorption
refrigerators in two different settings: namely, cavity and circuit quantum
electrodynamics. We first provide a unified description of these machines in
terms of the concept of virtual temperature. Next, we describe the two
different physical setups in detail and compare their properties and
performance. We conclude with an outlook on future work and open questions in
this field of research.Comment: Patrick P. Potts was formerly known as Patrick P. Hofe
A Hybrid Long-Distance Entanglement Distribution Protocol
We propose a hybrid (continuous-discrete variable) quantum repeater protocol
for distribution of entanglement over long distances. Starting from entangled
states created by means of single-photon detection, we show how entangled
coherent state superpositions, also known as `Schr\"odinger cat states', can be
generated by means of homodyne detection of light. We show that
near-deterministic entanglement swapping with such states is possible using
only linear optics and homodyne detectors, and we evaluate the performance of
our protocol combining these elements.Comment: 4 pages, 3 figure
Testing nonlocality of a single photon without a shared reference frame
The question of testing the nonlocality of a single photon has raised much
debate over the last years. The controversy is intimately related to the issue
of providing a common reference frame for the observers to perform their local
measurements. Here we address this point by presenting a simple scheme for
demonstrating the nonlocality of a single photon which does not require a
shared reference frame. Specifically, Bell inequality violation can be obtained
with certainty with unaligned devices, even if the relative frame fluctuates
between each experimental run of the Bell test. Our scheme appears feasible
with current technology, and may simplify the realization of quantum
communication protocols based on single-photon entanglement.Comment: 5 pages, 3 figure
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Evaluation of electroosmotic pumping effect in microporous media flow
This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.In this paper, the electroosmotic flow (EO) in desiccant powders of micro porous is
investigated regarding to the flow rate caused by the electroosmosis and the gravity. In particular, the coupling effect of electroosmosis and dehumidification in the flow is studied. It is noticeable that the actual electroosmosis pumping force maintains at a certain rate (10μL/min for the designed system). It is interpreted that the actual voltage from bench power is kept constant which exerts same effect of electric field on the desiccant particles. And during this stage the resistance inside the channel deceases with the rate of water entering into the electroosmosis pumping section which is affected by the capacity of dehumidification of the desiccant particles. Moreover, the mass flow rate by the effect of electroosmosis pumping can be achieved at 0.746 gm-2m-1 under 5V DC supply. These experimental results in this study provide useful instructions of electroosmosis performance for designing the micro porous channel in such as filtering the compounds of drug delivery, particle purification and liquid separation applications etc
Quantum Thermal Machine as a Thermometer
We propose the use of a quantum thermal machine for low-temperature
thermometry. A hot thermal reservoir coupled to the machine allows for
simultaneously cooling the sample while determining its temperature without
knowing the model-dependent coupling constants. In its most simple form, the
proposed scheme works for all thermal machines which perform at Otto efficiency
and can reach Carnot efficiency. We consider a circuit QED implementation which
allows for precise thermometry down to 15 mK with realistic parameters.
Based on the quantum Fisher information, this is close to the optimal
achievable performance. This implementation demonstrates that our proposal is
particularly promising in systems where thermalization between different
components of an experimental setup cannot be guaranteed.Comment: Main text: 5 pages, 4 figures; Supplement: 5 page
Single droplet experimentation on spray drying:evaporation of sessile droplets deposited on a flat surface
Abstract: Individually dispensed droplets were dried on a flat surface to mimic the drying of single droplets during spray drying. A robust dispensing process is presented that generates small droplets (dp>150 µm). A predictive model based on Bernoulli’s law accurately describes droplet size with varying liquids and dispensing parameters. Shrinkage of the droplets, monitored with a camera, was described using mass balance equations. Finally, a Sherwood correlation was derived to describe the mass transfer coefficient for sessile droplets. This work forms the basis for the development of a platform for high throughput experimentation on spray drying
Bell tests for continuous variable systems using hybrid measurements and heralded amplifiers
We present Bell tests for optical continuous variable systems, combining both
hybrid measurements (i.e. measuring both particle and wave aspects of light)
and heralded amplifiers. We discuss two types of schemes, in which the
amplifier is located either at the source, or at the parties' laboratories. The
inclusion of amplifiers helps to reduce the detrimental effect of losses in the
setup. In particular, we show that the requirements in terms of detection
efficiency and transmission losses are significantly reduced, approaching the
experimentally accessible regime.Comment: 6 pages, 5 figure
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