Why not Merge the International Monetary Fund (IMF) with the International Bank for Reconstruction and Development (World Bank)

Motivation: Cellular Electron CryoTomography (CECT) is an emerging 3D imaging technique that visualizes subcellular organization of single cells at sub-molecular resolution and in near-native state. CECT captures large numbers of macromolecular complexes of highly diverse structures and abundances. However, the structural complexity and imaging limits complicate the systematic de novo structural recovery and recognition of these macromolecular complexes. Efficient and accurate reference-free subtomogram averaging and classification represent the most critical tasks for such analysis. Existing subtomogram alignment based methods are prone to the missing wedge effects and low signal-to-noise ratio (SNR). Moreover, existing maximum-likelihood based methods rely on integration operations, which are in principle computationally infeasible for accurate calculation. Results: Built on existing works, we propose an integrated method, Fast Alignment Maximum Likelihood method (FAML), which uses fast subtomogram alignment to sample sub-optimal rigid transformations. The transformations are then used to approximate integrals for maximum-likelihood update of subtomogram averages through expectation-maximization algorithm. Our tests on simulated and experimental subtomograms showed that, compared to our previously developed fast alignment method (FA), FAML is significantly more robust to noise and missing wedge effects with moderate increases of computation cost. Besides, FAML performs well with significantly fewer input subtomograms when the FA method fails. Therefore, FAML can serve as a key component for improved construction of initial structuralmodels frommacromolecules captured by CECT

Floquet engineering of long-range p-wave superconductivity: Beyond the high-frequency limit

It has been shown that long-range {\it p}-wave superconductivity in a Kitaev chain can be engineered via an ac field with a high frequency [Benito et al., Phys. Rev. B 90, 205127 (2014)]. For its experimental realization, however, theoretical understanding of Floquet engineering with a broader range of driving frequencies becomes important. In this work, focusing on the ac-driven tunneling interactions of a Kitaev chain, we investigate effects from the leading correction to the high-frequency limit on the emergent {\it p}-wave superconductivity. Importantly, we find new engineered long-range {\it p}-wave pairing interactions that can significantly alter the ones in the high-frequency limit at long interaction ranges. We also find that the leading correction additionally generates nearest-neighbor {\it p}-wave pairing interactions with a renormalized pairing energy, long-range tunneling interactions, and in particular multiple pairs of Floquet Majorana edge states that are destroyed in the high- frequency limit.Comment: 13 pages, 8 figure

Collective quantum phase slips in multiple nanowire junctions

Realization of robust coherent quantum phase slips represents a significant experimental challenge. Here we propose a new design consisting of multiple nanowire junctions to realize a phase-slip flux qubit. It admits good tunability provided by gate voltages applied on superconducting islands separating nanowire junctions. In addition, the gates and junctions can be identical or distinct to each other leading to symmetric and asymmetric setups. We find that the asymmetry can improve the performance of the proposed device, compared with the symmetric case. In particular, it can enhance the effective rate of collective quantum phase slips. Furthermore, we demonstrate how to couple two such devices via a mutual inductance. This is potentially useful for quantum gate operations. Our investigation on how symmetry in multiple nanowire junctions affects the device performance should be useful for the application of phase-slip flux qubits in quantum information processing and quantum metrology.Comment: 12 pages, 6 figure

Cooling a nanomechanical resonator by a triple quantum dot

We propose an approach for achieving ground-state cooling of a nanomechanical resonator (NAMR) capacitively coupled to a triple quantum dot (TQD). This TQD is an electronic analog of a three-level atom in $\Lambda$ configuration which allows an electron to enter it via lower-energy states and to exit only from a higher-energy state. By tuning the degeneracy of the two lower-energy states in the TQD, an electron can be trapped in a dark state caused by destructive quantum interference between the two tunneling pathways to the higher-energy state. Therefore, ground-state cooling of an NAMR can be achieved when electrons absorb readily and repeatedly energy quanta from the NAMR for excitations.Comment: 6 pages, 3 figure