QUROPE Quantum Information Processing and Communication in Europe

Author(s): Dominik Lips, Artem Ryabov, and Philipp Maass

We study the driven Brownian motion of hard rods in a one-dimensional cosine potential with a large amplitude compared to the thermal energy. In a closed system, we find surprising features of the steady-state current in dependence of the particle density. The form of the current-density relation ch...

[Phys. Rev. Lett. 121, 160601] Published Tue Oct 16, 2018

Author(s): Jin Hyoun Kang, Jeong Ho Han, and Y. Shin

We report the experimental realization of a cross-linked chiral ladder with ultracold fermionic atoms in a 1D optical lattice. In the ladder, the legs are formed by the orbital states of the optical lattice and the complex interleg links are generated by the orbital-changing Raman transitions that a...

[Phys. Rev. Lett. 121, 150403] Published Fri Oct 12, 2018

Author(s): Hatem Barghathi, C. M. Herdman, and Adrian Del Maestro

Operationally accessible entanglement in bipartite systems of indistinguishable particles could be reduced due to restrictions on the allowed local operations as a result of particle number conservation. In order to quantify this effect, Wiseman and Vaccaro [Phys. Rev. Lett. 91, 097902 (2003)] intro...

[Phys. Rev. Lett. 121, 150501] Published Fri Oct 12, 2018

Author(s): Yaoyao Zhou, Juan Yu, Zhihui Yan, Xiaojun Jia, Jing Zhang, Changde Xie, and Kunchi Peng

Secret sharing is a conventional technique for realizing secure communications in information networks, where a dealer distributes to n players a secret, which can only be decoded through the cooperation of k (n/2<k≤n) players. In recent years, quantum resources have been employed to enhance secu...

[Phys. Rev. Lett. 121, 150502] Published Fri Oct 12, 2018

Author(s): Johnnie Gray, Leonardo Banchi, Abolfazl Bayat, and Sougato Bose

Entanglement not only plays a crucial role in quantum technologies, but is key to our understanding of quantum correlations in many-body systems. However, in an experiment, the only way of measuring entanglement in a generic mixed state is through reconstructive quantum tomography, requiring an expo...

[Phys. Rev. Lett. 121, 150503] Published Fri Oct 12, 2018

Author(s): Daniel Martínez, Armin Tavakoli, Mauricio Casanova, Gustavo Cañas, Breno Marques, and Gustavo Lima

Quantum resources can improve communication complexity problems (CCPs) beyond their classical constraints. One quantum approach is to share entanglement and create correlations violating a Bell inequality, which can then assist classical communication. A second approach is to resort solely to the pr...

[Phys. Rev. Lett. 121, 150504] Published Fri Oct 12, 2018

Author(s): Mihail Poplavskyi and Grégory Schehr

We compute the persistence for the 2D-diffusion equation with random initial condition, i.e., the probability p0(t) that the diffusion field, at a given point x in the plane, has not changed sign up to time t. For large t, we show that p0(t)∼t−θ(2) with θ(2)=3/16. Using the connection between the 2D...

[Phys. Rev. Lett. 121, 150601] Published Fri Oct 12, 2018

Author(s): Wei Sun, Bao-Zong Wang, Xiao-Tian Xu, Chang-Rui Yi, Long Zhang, Zhan Wu, Youjin Deng, Xiong-Jun Liu, Shuai Chen, and Jian-Wei Pan

We report the realization of a robust and highly controllable two-dimensional (2D) spin-orbit (SO) coupling with a topological nontrivial band structure. By applying a retro-reflected 2D optical lattice, phase tunable Raman couplings are formed into the antisymmetric Raman lattice structure, and gen...

[Phys. Rev. Lett. 121, 150401] Published Tue Oct 09, 2018

Author(s): Lijiong Shen, Jianwei Lee, Le Phuc Thinh, Jean-Daniel Bancal, Alessandro Cerè, Antia Lamas-Linares, Adriana Lita, Thomas Gerrits, Sae Woo Nam, Valerio Scarani, and Christian Kurtsiefer

We present a violation of the Clauser-Horne-Shimony-Holt inequality without the fair sampling assumption with a continuously pumped photon pair source combined with two high efficiency superconducting detectors. Because of the continuous nature of the source, the choice of the duration of each measu...

[Phys. Rev. Lett. 121, 150402] Published Tue Oct 09, 2018

Author(s): Hal Tasaki

We study S=1 quantum spin systems on the infinite chain with short ranged Hamiltonians that have a certain rotational and discrete symmetry. We define a Z2 index for any gapped unique ground state, and prove that it is invariant under a smooth deformation. By using the index, we provide the first ri...

[Phys. Rev. Lett. 121, 140604] Published Fri Oct 05, 2018

Author(s): J. Runeson, M. Nava, and M. Parrinello

We address the problem of the minus sign sampling for two-electron systems using the path integral approach. We show that this problem can be reexpressed as one of computing free energy differences and sampling the tails of statistical distributions. Using metadynamics, a realistic problem like that...

[Phys. Rev. Lett. 121, 140602] Published Wed Oct 03, 2018

Author(s): Ping Fang, Liyi Zhao, and Chushun Tian

The emergence of nonequilibrium phenomena in individual complex wave systems has long been of fundamental interest. Its analytic studies remain notoriously difficult. Using the mathematical tool of the concentration of measure, we develop a theory for structures and fluctuations of waves in individu...

[Phys. Rev. Lett. 121, 140603] Published Wed Oct 03, 2018

Author(s): Thimothée Thiery, François Huveneers, Markus Müller, and Wojciech De Roeck

We propose a multiscale diagonalization scheme to study disordered one-dimensional chains, in particular, the transition between many-body localization (MBL) and the ergodic phase, expected to be governed by resonant spots. Our scheme focuses on the dichotomy of MBL versus validity of the eigenstate...

[Phys. Rev. Lett. 121, 140601] Published Tue Oct 02, 2018

Author(s): Gonzalo Carvacho, Francesco Andreoli, Luca Santodonato, Marco Bentivegna, Vincenzo D’Ambrosio, Paul Skrzypczyk, Ivan Šupić, Daniel Cavalcanti, and Fabio Sciarrino

Quantum teleportation establishes a correspondence between an entangled state shared by two separate parties that can communicate classically and the presence of a quantum channel connecting the two parties. The standard benchmark for quantum teleportation, based on the average fidelity between the ...

[Phys. Rev. Lett. 121, 140501] Published Mon Oct 01, 2018

Author(s): R. Rossi, T. Ohgoe, K. Van Houcke, and F. Werner

We demonstrate that a summing up series of Feynman diagrams can yield unbiased accurate results for strongly correlated fermions even when the convergence radius vanishes. We consider the unitary Fermi gas, a model of nonrelativistic fermions in three-dimensional continuous space. Diagrams are built...

[Phys. Rev. Lett. 121, 130405] Published Thu Sep 27, 2018

Author(s): R. Rossi, T. Ohgoe, E. Kozik, N. Prokof’ev, B. Svistunov, K. Van Houcke, and F. Werner

A key quantity in strongly interacting resonant Fermi gases is the contact C, which characterizes numerous properties such as the momentum distribution at large momenta or the pair correlation function at short distances. The temperature dependence of C was measured at unitarity, where existing theo...

[Phys. Rev. Lett. 121, 130406] Published Thu Sep 27, 2018

Author(s): Manuel Gessner, Luca Pezzè, and Augusto Smerzi

We identify precision limits for the simultaneous estimation of multiple parameters in multimode interferometers. Quantum strategies to enhance the multiparameter sensitivity are based on entanglement among particles, modes, or combining both. The maximum attainable sensitivity of particle-separable...

[Phys. Rev. Lett. 121, 130503] Published Thu Sep 27, 2018

Author(s): Ezad Shojaee, Christopher S. Jackson, Carlos A. Riofrío, Amir Kalev, and Ivan H. Deutsch

The spin-coherent-state positive-operator-valued-measure (POVM) is a fundamental measurement in quantum science, with applications including tomography, metrology, teleportation, benchmarking, and measurement of Husimi phase space probabilities. We prove that this POVM is achieved by collectively me...

[Phys. Rev. Lett. 121, 130404] Published Wed Sep 26, 2018

Author(s): Shiqian Ding, Gleb Maslennikov, Roland Hablützel, and Dzmitry Matsukevich

Interaction among harmonic oscillators described by a trilinear Hamiltonian ℏξ(a†bc+ab†c†) is one of the most fundamental models in quantum optics. By employing the anharmonicity of the Coulomb potential in a linear trapped three-ion crystal, we experimentally implement it among three normal modes o...

[Phys. Rev. Lett. 121, 130502] Published Wed Sep 26, 2018

Author(s): S. Scherg, T. Kohlert, J. Herbrych, J. Stolpp, P. Bordia, U. Schneider, F. Heidrich-Meisner, I. Bloch, and M. Aidelsburger

We experimentally and numerically investigate the sudden expansion of fermions in a homogeneous one-dimensional optical lattice. For initial states with an appreciable amount of doublons, we observe a dynamical phase separation between rapidly expanding singlons and slow doublons remaining in the tr...

[Phys. Rev. Lett. 121, 130402] Published Tue Sep 25, 2018