Sökresultat

This paper aims at evaluating the changes that head rotation poses on morphological and flow characteristics of the carotid bifurcation (CB) and on the distribution of parameters that are regarded as important in atherosclerosis development, such as relative particle residence time (RRT), normalized oscillatory shear index (nOSI), and helicity (HL). Using a subject-specific approach, six healthy v

Atherosclerosis is the third leading cause of morbidity and mortality in the Western world. Low and oscillating wall shear stress (WSS) regions have been previously reported as parameters that correlate with the development of atherosclerosis. In this study we investigated geometric and hemodynamic changes in the carotid bifurcation as a result of posture change. Data from magnetic resonance imagi

An implementation of a small quantum absorption refrigerator in a circuit QED architecture is proposed. The setup consists of three harmonic oscillators coupled to a Josephson junction. The refrigerator is autonomous in the sense that it does not require any external control for cooling, but only thermal contact between the oscillators and heat baths at different temperatures. In addition, the set

Motivated by recent progress in electron quantum optics, we revisit the question of single-electron entanglement, specifically whether the state of a single electron in a superposition of two separate spatial modes should be considered entangled. We first discuss a gedanken experiment with single-electron sources and detectors, and demonstrate deterministic (i. e. without post-selection) Bell ineq

The Keldysh-ordered full counting statistics is a quasiprobability distribution describing the fluctuations of a time-integrated quantum observable. While it is well known that this distribution can fail to be positive, the interpretation and origin of this negativity has been somewhat unclear. Here, we show how the full counting statistics can be tied to trajectories through Hilbert space, and ho

We evaluate the distribution of waiting times between electrons emitted by a driven mesoscopic capacitor. Based on a wave packet approach we obtain analytic expressions for the electronic waiting time distribution and the joint distribution of subsequent waiting times. These semi-classical results are compared to a full quantum treatment based on Floquet scattering theory and good agreement is fou

We evaluate the joint distributions of electron waiting times in coherent conductors described by scattering theory. Successive electron waiting times in a single-channel conductor are found to be correlated due to the fermionic statistics encoded in the many-body state. Our formalism allows us also to investigate the waiting times between charge transfer events in different outgoing channels. As

We theoretically investigate the thermoelectric properties of heat engines based on Mach-Zehnder interferometers. The energy dependence of the transmission amplitudes in such setups arises from a difference in the interferometer arm lengths. Any thermoelectric response is thus of purely quantum-mechanical origin. In addition to an experimentally established three-terminal setup, we also consider a

We propose and analyze a simple mesoscopic quantum heat engine that exhibits both high power and high efficiency. The system consists of a biased Josephson junction coupled to two microwave cavities, with each cavity coupled to a thermal bath. Resonant Cooper pair tunneling occurs with the exchange of photons between cavities, and a temperature difference between the baths can naturally lead to a

We investigate theoretically a Mach-Zehnder interferometer driven by a time-dependent voltage. Motivated by recent experiments, we focus on a train of Lorentzian voltage pulses which we compare to a sinusoidal and a constant voltage. We discuss the visibilities of Aharonov-Bohm oscillations in the current and in the noise. For the current, we find a strikingly different behavior in the driven as c

We propose an ac current source that can be tuned from a pure charge to a pure spin current source. The device consists of two mesoscopic capacitors attached to a two-dimensional strip of a topological insulator. The change from charge to spin current is controlled by an offset in the top gate potentials that drive the capacitors. In addition to this setup, which anticipates the experimental reali

We propose a single-particle source which emits into the helical edge states of a two-dimensional quantum spin Hall insulator. Without breaking time-reversal symmetry, this source acts like a pair of noiseless single-electron emitters which each inject separately into a chiral edge state. By locally breaking time-reversal symmetry, the source becomes a proper single-particle emitter which exhibits

We study two-species Bose-Einstein condensates in quasi-two-dimensional optical lattices of varying geometry and potential depth. Based on the numerically exact Bloch and Wannier functions obtained using the plane-wave expansion method, we quantify the drag (entrainment coupling) between the condensate components. This drag originates from the (short-range) interspecies interaction and increases w

Limiting spatial resolution is a key metric of the quality of magnetic resonance MR images, which can provide an indication of the smallest region that can effectively be imaged. In this paper a novel methodology for measuring the limiting spatial resolution of MR images is mathematically analyzed and successfully implemented on phantom images. The methodology presented in this paper is based on a

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

Cardiovascular disease is the leading cause of death in the western world. With the application of theoretical physics to the clinic, a variety of imaging technologies are available to the physician for diagnosing and accurately quantifying disease progression. These tools can influence how therapies are applied and impact patient outcome. Radiographic methods based on x-rays are used for diagnosi