Detection of qubit-oscillator entanglement in nanoelectromechanical systems

Experiments over the past years have demonstrated that it is possible to bring nanomechanical resonators and superconducting qubits close to the quantum regime and to measure their properties with an accuracy close to the Heisenberg uncertainty limit. Therefore, it is just a question of time before we will routinely see true quantum effects in nanomechanical systems. One of the hallmarks of quantum mechanics is the existence of entangled states. We propose a realistic scenario making it possible to detect entanglement of a mechanical resonator and a qubit in a nanoelectromechanical setup. The detection scheme involves only standard current and noise measurements of an atomic point contact coupled to an oscillator and a qubit. This setup could allow for the first observation of entanglement between a continuous and a discrete quantum system in the solid state.Comment: 9 pages, 3 figure

Full counting statistics of Majorana interferometers

We study the full counting statistics of interferometers for chiral Majorana fermions with two incoming and two outgoing Dirac fermion channels. In the absence of interactions, the FCS can be obtained from the $4\times4$ scattering matrix $S$ that relates the outgoing Dirac fermions to the incoming Dirac fermions. After presenting explicit expressions for the higher-order current correlations for a modified Hanbury Brown-Twiss interferometer, we note that the cumulant-generating function can be interpreted such that unit-charge transfer processes correspond to two independent half-charge transfer processes, or alternatively, to two independent electron-hole conversion processes. By a combination of analytical and numerical approaches, we verify that this factorization property holds for a general $SO(4)$ scattering matrix, i.e. for a general interferometer geometry.Comment: 22 pages, 3 figures, contributed to the special issue of Physica E "Frontiers in Quantum Electronic Transport - In Memory of Markus Buttiker

Charge and spin density modulations in semiconductor quantum wires

We investigate static charge and spin density modulation patterns along a ferromagnet/semiconductor single junction quantum wire in the presence of spin-orbit coupling. Coherent scattering theory is used to calculate the charge and spin densities in the ballistic regime. The observed oscillatory behavior is explained in terms of the symmetry of the charge and spin distributions of eigenstates in the semiconductor quantum wire. Also, we discuss the condition that these charge and spin density oscillations can be observed experimentally.Comment: 7 pages, 8 figures (low-resolution

Identifying differences in the experience of (in)authenticity: a latent class analysis approach

Generally, psychologists consider state authenticity– that is, the subjective sense of being one’s true self – to be a unitary and unidimensional construct, such that (a) the phenomenological experience of authenticity is thought to be similar no matter its trigger, and (b) inauthenticity is thought to be simply the opposing pole (on the same underlying construct) of authenticity. Using latent class analysis, we put this conceptualization to a test. In order to avoid over-reliance on a Western conceptualization of authenticity, we used a cross-cultural sample (N = 543), comprising participants from Western, South-Asian, East-Asian, and South-East Asian cultures. Participants provided either a narrative in which the described when they felt most like being themselves or one in which they described when they felt least like being themselves. The analysis identified six distinct classes of experiences: two authenticity classes ('everyday' and 'extraordinary'), three inauthenticity classes ('self-conscious,' 'deflated,' and 'extraordinary'), and a class representing convergence between authenticity and inauthenticity. The classes were phenomenologically distinct, especially with respect to negative affect, private and public self-consciousness, and self-esteem. Furthermore, relatively more interdependent cultures were less likely to report experiences of extraordinary (in)authenticity than relatively more independent cultures. Understanding the many facets of (in)authenticity may enable researchers to connect different findings and explain why the attainment of authenticity can be difficult

Asymmetric Quantum Shot Noise in Quantum Dots

We analyze the frequency-dependent noise of a current through a quantum dot which is coupled to Fermi leads and which is in the Coulomb blockade regime. We show that the asymmetric shot noise as function of frequency shows steps and becomes super-Poissonian. This provides experimental access to the quantum fluctuations of the current. We present an exact calculation for a single dot level and a perturbative evaluation of the noise in Born approximation (sequential tunneling regime but without Markov approximation) for the general case of many levels with charging interaction.Comment: 5 pages, 2 figure

Trait and state authenticity across cultures

We examined the role of culture in both trait and state authenticity, asking whether the search for and experience of the 'true self' is a uniquely Western phenomenon or is relevant cross-culturally. We tested participants from the US, China, India, and Singapore. US participants reported higher average levels of trait authenticity than those from Eastern cultures (i.e., China, India, Singapore), but this effect was partially explained by cultural differences in self-construal and thinking style. Importantly, the experience of state authenticity, and especially state inauthenticity, was more similar than different across cultures. In all, people from different cultures do experience authenticity, even if they do not endorse the (Western) value of “independence.” The findings contribute to a more nuanced understanding of state authenticity

How does “being real” feel? The experience of state authenticity

Objective: We propose that the experience of state authenticity—the subjective sense of being one's true self—ought to be considered separately from trait authenticity as well as from prescriptions regarding what should make people feel authentic. Methods: In Study 1 (N  = 104), online participants rated the frequency of and motivation for experiences of authenticity and inauthenticity. Studies 2 (N = 268) and 3 (N  = 93) asked (local or online, respectively) participants to describe their experiences of authenticity or inauthenticity. Participants in Studies 1 and 2 also completed measures of trait authenticity, and participants in Study 3 rated their experience with respect to several phenomenological dimensions. Results: Study 1 demonstrated that people are motivated to experience state authenticity and avoid inauthenticity and that such experiences are common, regardless of one's degree of trait authenticity. Coding of Study 2's narratives identified the emotions accompanying and needs fulfilled in each state. Trait authenticity generally did not qualify the nature of (in)authentic experiences. Study 3 corroborated the results of Study 2 and further revealed positive mood and nostalgia as consequences of reflecting on experiences of authenticity. Conclusions: We discuss implications of these findings for conceptualizations of authenticity and the self

Paramagnetic reentrant effect in high purity mesoscopic AgNb proximity structures

We discuss the magnetic response of clean Ag coated Nb proximity cylinders in the temperature range 150 \mu K < T < 9 K. In the mesoscopic temperature regime, the normal metal-superconductor system shows the yet unexplained paramagnetic reentrant effect, discovered some years ago [P. Visani, A. C. Mota, and A. Pollini, Phys. Rev. Lett. 65, 1514 (1990)], superimposing on full Meissner screening. The logarithmic slope of the reentrant paramagnetic susceptibility chi_para(T) \propto \exp(-L/\xi_N) is limited by the condition \xi_N=n L, with \xi_N=\hbar v_F/2 \pi k_B T, the thermal coherence length and n=1,2,4. In wires with perimeters L=72 \mu m and L=130 \mu m, we observe integer multiples n=1,2,4. At the lowest temperatures, \chi_para compensates the diamagnetic susceptibility of the \textit{whole} AgNb structure.Comment: 4 pages, 4 figures (color

The New Generation of Computer Literacy

A tremendous mismatch is developing between two of the most critical components of any computer literacy course: the textbooks and the students. We are encountering a new generation of students (literally as well as figuratively!) who are much better acquainted with computer usage than their earlier counterparts. Yet many textbooks with increasing emphasis in those same computer tools continue to appear. There are signs of a coming change in that a few authors and publishers apparently are becoming aware of the need for innovations in texts for non-scientists. These textbooks open the door for a new orientation to principles in the teaching of computer literacy

Electric instability in superconductor-normal conductor ring

Non-linear electrodynamics of a ring-shaped Andreev interferometer (superconductor-normal conductor-superconductor hybrid structure) inductively coupled to a circuit of the dissipative current is investigated. The current-voltage characteristics (CVC) is demonstrated to be a series of loops with several branches intersecting in the CVC origin. The sensitivity of the transport current to a change of the applied external magnetic flux can be comparable to the one of the conventional SQUID's. Spontaneous arising of coupled non-linear oscillations of the transport current, the Josephson current and the magnetic flux in Andreev interferometers are also predicted and investigated. The frequency of these oscillations can be varied in a wide range, while the maximal frequency can reach $\omega_{max} \sim 10^{12}$ $sec^{-1}$.Comment: 4 pages, 4 figure