Unconventional Fermi surface instabilities in the Kagome Hubbard Model

We investigate the competing Fermi surface instabilities in the Kagome tight-binding model. Specifically, we consider onsite and short-range Hubbard interactions in the vicinity of van Hove filling of the dispersive Kagome bands where the Fermiology promotes the joint effect of enlarged density of states and nesting. The sublattice interference mechanism [Kiesel and Thomale, Phys. Rev. B Rapid Comm., in press.] allows us to explain the intricate interplay between ferromagnetic fluctuations and other ordering tendencies. On the basis of functional renormalization group used to obtain an adequate low-energy theory description, we discover finite angular momentum spin and charge density wave order, a two-fold degenerate d-wave Pomeranchuk instability, and f-wave superconductivity away from van Hove filling. Together, this makes the Kagome Hubbard model the prototypical scenario for several unconventional Fermi surface instabilities.Comment: 4+e pages, 5 figure

Sublattice Interference in the Kagome Hubbard Model

We study the electronic phases of the kagome Hubbard model (KHM) in the weak coupling limit around van Hove filling. Through an analytic renormalization group analysis, we find that there exists a sublattice interference mechanism where the kagome sublattice structure affects the character of the Fermi surface instabilities. It leads to major suppression of Tc for d+id superconductivity in the KHM and causes an anomalous increase of Tc upon addition of longer-range Hubbard interactions. We conjecture that the suppression of conventional Fermi liquid instabilities makes the KHM a prototype candidate for hosting exotic electronic states of matter at intermediate coupling.Comment: 4+e pages, 3 figure

Multi-qubit entanglement engineering via projective measurements

So far, various multi-photon entangled states have been observed experimentally by using different experimental set-ups. Here, we present a scheme to realize many SLOCC-inequivalent states of three and four qubits via projective measurements on suitable entangled states. We demonstrate how these states can be observed experimentally in a single set-up and study the feasibility of the implementation with present-day technology

Experimental implementation of a four-player quantum game

Game theory is central to the understanding of competitive interactions arising in many fields, from the social and physical sciences to economics. Recently, as the definition of information is generalized to include entangled quantum systems, quantum game theory has emerged as a framework for understanding the competitive flow of quantum information. Up till now only two-player quantum games have been demonstrated. Here we report the first experiment that implements a four-player quantum Minority game over tunable four-partite entangled states encoded in the polarization of single photons. Experimental application of appropriate quantum player strategies give equilibrium payoff values well above those achievable in the classical game. These results are in excellent quantitative agreement with our theoretical analysis of the symmetric Pareto optimal strategies. Our result demonstrate for the first time how non-trivial equilibria can arise in a competitive situation involving quantum agents and pave the way for a range of quantum transaction applications.Comment: 9 pages, 5 figure

Optical Quantum Computing

In 2001 all-optical quantum computing became feasible with the discovery that scalable quantum computing is possible using only single photon sources, linear optical elements, and single photon detectors. Although it was in principle scalable, the massive resource overhead made the scheme practically daunting. However, several simplifications were followed by proof-of-principle demonstrations, and recent approaches based on cluster states or error encoding have dramatically reduced this worrying resource overhead, making an all-optical architecture a serious contender for the ultimate goal of a large-scale quantum computer. Key challenges will be the realization of high-efficiency sources of indistinguishable single photons, low-loss, scalable optical circuits, high efficiency single photon detectors, and low-loss interfacing of these components.Comment: 5 pages, 4 figure

Engineering a C-Phase quantum gate: optical design and experimental realization

A two qubit quantum gate, namely the C-Phase, has been realized by exploiting the longitudinal momentum (i.e. the optical path) degree of freedom of a single photon. The experimental setup used to engineer this quantum gate represents an advanced version of the high stability closed-loop interferometric setup adopted to generate and characterize 2-photon 4-qubit Phased Dicke states. Some experimental results, dealing with the characterization of multipartite entanglement of the Phased Dicke states are also discussed in detail.Comment: accepted for publication on EPJ

mRNA-Expression of ERα, ERβ, and PR in Clonal Stem Cell Cultures Obtained from Human Endometrial Biopsies

Background. Proliferation and differentiation of the endometrium are regulated by estrogen and progesterone. The enormous regenerative capacity of the endometrium is thought to be based on the activity of adult stem cells. However, information on endocrine regulatory mechanisms in human endometrial stem cells is scarce. In the present study, we investigated the expression of ERα, ERβ, and PR in clonal cultures of human endometrial stem cells derived from transcervical biopsies. Methods. Endometrial tissue of 11 patients was obtained by transcervical biopsy. Stromal cell suspensions were plated at clonal density and incubated for 15 days. Expression of ERα, ERβ and PR was determined by qPCR prior to and after one cloning round, and normalized to 18 S rRNA expression. Results. Expression of ERα and ERβ was downregulated by 64% and 89%, respectively (P = 0.002 and P < 0.001). In contrast, PR was not significantly downregulated, due to a more heterogenous expression pattern. Conclusions. Culture of human endometrial stroma cells results in a downregulation of ERα and ERβ, while expression of PR remained unchanged in our patient collective. These results support the hypothesis that stem cells may not be subject to direct stimulation by sex steroids, but rather by paracrine mechanisms within the stem cell niche

Nonequilibrium Quantum Thermodynamics of a Particle Trapped in a Controllable Time-Varying Potential

Many advanced quantum techniques feature non-Gaussian dynamics, and the ability to manipulate the system in that domain is the next stage in many experiments. One example of meaningful non-Gaussian dynamics is that of a double-well potential. Here we study the dynamics of a levitated nanoparticle undergoing the transition from a harmonic potential to a double well in a realistic setting, subjected to both thermalization and localization. We characterize the dynamics of the nanoparticle from a thermodynamic point of view, investigating the dynamics with the Wehrl entropy production and its rates. Furthermore, we investigate coupling regimes where the the quantum effect and thermal effect are of the same magnitude, and look at suitable squeezing of the initial state that provides the maximum coherence. The effects and the competitions of the unitary and the dissipative parts onto the system are demonstrated. We quantify the requirements to relate our results to a bonafide experiment with the presence of the environment, and discuss the experimental interpretations of our results in the end

Realization of a Knill-Laflamme-Milburn C-NOT gate -a photonic quantum circuit combining effective optical nonlinearities

Quantum information science addresses how uniquely quantum mechanical phenomena such as superposition and entanglement can enhance communication, information processing and precision measurement. Photons are appealing for their low noise, light-speed transmission and ease of manipulation using conventional optical components. However, the lack of highly efficient optical Kerr nonlinearities at single photon level was a major obstacle. In a breakthrough, Knill, Laflamme and Milburn (KLM) showed that such an efficient nonlinearity can be achieved using only linear optical elements, auxiliary photons, and measurement. They proposed a heralded controlled-NOT (CNOT) gate for scalable quantum computation using a photonic quantum circuit to combine two such nonlinear elements. Here we experimentally demonstrate a KLM CNOT gate. We developed a stable architecture to realize the required four-photon network of nested multiple interferometers based on a displaced-Sagnac interferometer and several partially polarizing beamsplitters. This result confirms the first step in the KLM `recipe' for all-optical quantum computation, and should be useful for on-demand entanglement generation and purification. Optical quantum circuits combining giant optical nonlinearities may find wide applications across telecommunications and sensing.Comment: 6pages, 3figure

The hyaluronan-related genes HAS2, HYAL1-4, PH20 and HYALP1 are associated with prognosis, cell viability and spheroid formation capacity in ovarian cancer

Purpose: Hyaluronan modulates tumour progression, including cell adhesion, cohesion, proliferation and invasion, and the cancer stem cell phenotype. In ovarian cancer, high levels of stromal hyaluronan are associated with poor prognosis. In this work, hyaluronan synthases (HAS1-3) and hyaluronidases (HYAL1-4, PH-20, HYALP1) were examined with regard to different levels of gene expression and its influence on ovarian cancer patients’ survival. The impact of a siRNA depletion of HAS2 was investigated in vitro. Methods: Using the Kaplan–Meier Plotter tool, we investigated the influence of hyaluronic synthases and hyaluronidases on the survival of a collective of 1435 ovarian cancer patients. Differences in gene expression between normal (n = 46) and cancerous (n = 744) ovarian tissue were examined using the TNMplot database. Following an evaluation of hyaluronan-related gene expression in the ATCC ovarian cancer panel, we studied SKOV3 and SW 626 ovarian cancer cells subjected to HAS2 siRNA or control siRNA treatment in terms of HAS1-3, HYAL2 and HYAL3 mRNA expression. We investigated the ability to form spheroids using the Hanging Drop method and the response to chemotherapy at different concentrations using the MTT Assay. By STRING analysis, interactions within the enzymes of the hyaluronic acid system and with binding partners were visualized. Results: HAS1, HYAL1 and HYAL4 mRNA expression is significantly upregulated, whereas HAS2, HYAL2 and HYAL3 mRNA expression is significantly downregulated in ovarian cancer tissue compared to controls. HAS2 improves cell viability, the capability to form tumour spheroids and has a negative prognostic value regarding overall survival. Lower HAS2 expression and high expression of HYAL2 and HYAL3 favours the survival of ovarian cancer patients. HAS2 knockdown cells and control cells showed a moderate response to combinatorial in vitro chemotherapy with taxol and cisplatin. Conclusion: In conclusion, our study shows that the hyaluronic acid system has a relevant influence on the survival of ovarian cancer patients and could therefore be considered as a possible prognostic factor