QUROPE Quantum Information Processing and Communication in Europe

Author(s): Tatsuma Nishioka

In this review the entanglement and Renyi entropies in quantum field theory are described from different points of view, including the perturbative approach and holographic dualities. The applications of these results to constraining renormalization group flows are presented effectively and illustrated with a variety of examples.

[Rev. Mod. Phys. 90, 035007] Published Mon Sep 17, 2018

Author(s): Luca Pezzè, Augusto Smerzi, Markus K. Oberthaler, Roman Schmied, and Philipp Treutlein

Entanglement is the basis of quantum technologies aimed at revolutionizing measurements, computing, and communications. This article reviews methods to improve measurement precision and sensitivity by harnessing entangled states of many atomic probe particles. The achievements of different experimental entanglement schemes are presented with theoretical analyses of their fundamental and practical limits, discussing prospects for applications in clocks, frequency standards, and measurements of forces and fields.

[Rev. Mod. Phys. 90, 035005] Published Wed Sep 05, 2018

Author(s): Daniel Braun, Gerardo Adesso, Fabio Benatti, Roberto Floreanini, Ugo Marzolino, Morgan W. Mitchell, and Stefano Pirandola

Entangled quantum states can enhance measurement precision. But quantum mechanics harbors other possibilities for enhancing precision, including some that have nothing to do with entanglement. This review surveys various strategies with unentangled probes by which measurements have been improved. Among the approaches considered are those that rely on particle statistics and correlations in highly mixed states. Often nonentangled states are more robust, and these approaches are feasible in current experiments: here the current states of research are shown in cold atoms, nonlinear optics, and nanomechanical oscillators.

[Rev. Mod. Phys. 90, 035006] Published Wed Sep 05, 2018

Author(s): Martin Freer, Hisashi Horiuchi, Yoshiko Kanada-En’yo, Dean Lee, and Ulf-G. Meißner

In most nuclei, protons and neutrons are smoothly distributed throughout the nuclear volume. Exceptions to this rule are molecularlike states, especially in light nuclei, where light nuclear clusters such as alpha particles are present. The most prominent example is the 7.65 MeV Hoyle state in carbon-12 that plays an essential role in the production of carbon in stars in the triple-alpha process. This work reviews progress and prospects in the studies of nuclear clustering, including molecular states in alpha-conjugate and neutron-rich systems.

[Rev. Mod. Phys. 90, 035004] Published Tue Aug 28, 2018

Author(s): Seogjoo J. Jang and Benedetta Mennucci

Photosynthetic bacteria, algae, and plants convert solar energy into biochemical fuel via light-harvesting complexes comprised of proteins and pigments. Pigments absorb photons by exciting electron-hole pairs that move readily to other pigments. How biology utilizes such quantum processes at room temperature to achieve efficiency of energy transfer is of interest to physicists. This article reviews computational and spectroscopic advances in understanding the energy conversion and energy transport of such a magnificent nanorectenna.

[Rev. Mod. Phys. 90, 035003] Published Tue Aug 21, 2018

Author(s): Evelyn Tang and Danielle S. Bassett

Biological networks are notoriously complex to understand and hence challenging to control. The brain is possibly the most sophisticated network in nature and only recently have we started to comprehend the mechanics of its operation and control. This Colloquium reviews the latest theoretical and technological developments in this emergent and exciting area of research.

[Rev. Mod. Phys. 90, 031003] Published Tue Aug 14, 2018

Author(s): M. C. Downer, R. Zgadzaj, A. Debus, U. Schramm, and M. C. Kaluza

Plasma-based electron accelerators rely on excitation of light-speed plasma density waves and associated ultrahigh electric fields to accelerate electrons to ultrarelativistic energy. Intrinsic time and length scales of these plasma waves are typically a few tens of femtoseconds and micrometers and result in ultrashort electron bunches with often even smaller temporal and spatial dimensions. In this article the progress and challenges of diagnosing the plasma waves, the excited fields, and ensuing particle bunches are reviewed.

[Rev. Mod. Phys. 90, 035002] Published Wed Aug 08, 2018

Author(s): D. E. Chang, J. S. Douglas, A. González-Tudela, C.-L. Hung, and H. J. Kimble

Quantum optics has advanced tremendously over the past two decades by combining ultracold atoms with diverse optical systems. However, fundamental and technical issues place constraints that limit further advances. This Colloquium examines new paradigms for strong quantum interactions of matter and light by way of atoms and photons in nanoscopic dielectric lattices, including novel quantum phases of atoms, photons, and phonons.

[Rev. Mod. Phys. 90, 031002] Published Wed Aug 01, 2018

Author(s): Andrea Giammanco and Reinhard Schwienhorst

The top quark was discovered and extensively studied in strong interactions that produce top-antitop pairs. The companion process in which a single top quark is produced in electroweak interactions offers many complementary insights into top quark production and properties that are sensitive to a variety of possible nonstandard model interactions.

[Rev. Mod. Phys. 90, 035001] Published Wed Jul 18, 2018

Author(s): Miguel A. Muñoz

Close to a transition between different phases a substance can show universal behavior that is independent of the microscopic details and is characterized by power law correlations and critical exponents. In this Colloquium the concepts of criticality and universality are discussed when applied to biological systems and suggest that in some cases these systems can extract functional advantages close to criticality.

[Rev. Mod. Phys. 90, 031001] Published Tue Jul 10, 2018

Author(s): M. S. Safronova, D. Budker, D. DeMille, Derek F. Jackson Kimball, A. Derevianko, and Charles W. Clark

Advances in atomic physics, such as cooling and trapping of atoms and molecules and developments in frequency metrology, have added orders of magnitude to the precision of atom-based clocks and sensors. Applications extend beyond atomic physics and this article reviews using these new techniques to address important challenges in physics and to look for variations in the fundamental constants, search for interactions beyond the standard model of particle physics, and test the principles of general relativity.

[Rev. Mod. Phys. 90, 025008] Published Fri Jun 29, 2018

Author(s): Lorenzo Mino, Elisa Borfecchia, Jaime Segura-Ruiz, Cinzia Giannini, Gema Martinez-Criado, and Carlo Lamberti

The Moore’s law trajectory of hard x-ray spatial resolution extrapolates to a few nanometers within the next few years, thereby promising critical space-resolved structural, electronic, and compositional nanoscale characterizations for a wide variety of materials. This review addresses the capabilities and advantages of x-ray microbeam and nanobeam techniques compared to photon, electron, neutron, and ion probes through selected applications including semiconductors, superconductors, metals, and nanostructured devices.

[Rev. Mod. Phys. 90, 025007] Published Thu Jun 28, 2018

Author(s): A. Kashlinsky, R. G. Arendt, F. Atrio-Barandela, N. Cappelluti, A. Ferrara, and G. Hasinger

While the cosmic microwave background originates from the very early Universe, the cosmic infrared background contains the cumulative emission of sources from the earliest epochs to the present time. It is generated from nucleosynthetic sources and gravitational sources. The source-subtracted spatial fluctuations of the cosmic infrared background provide information on the brightness and clustering of sources too faint to detect individually. Among these are the very first stars in the Universe and an unexpectedly large fraction of black holes. Observational and theoretical efforts at decoding the cosmic infrared background are presented together with possible future tests and prospects.

[Rev. Mod. Phys. 90, 025006] Published Tue Jun 19, 2018

Author(s): Megan Connors, Christine Nattrass, Rosi Reed, and Sevil Salur

The hottest matter that existed in the early Universe after the big bang, the quark-gluon plasma, is created in ultrarelativistic collisions of heavy nuclei. By studying narrow streams of fast-moving particles coming from the collisions, nuclear physicists learn about properties of this hot, dense medium. This work reviews current experimental evidence and related theoretical descriptions of the plasma’s constituents and properties.

[Rev. Mod. Phys. 90, 025005] Published Tue Jun 12, 2018

Author(s): Florian Fröwis, Pavel Sekatski, Wolfgang Dür, Nicolas Gisin, and Nicolas Sangouard

Schrödinger’s thought experiment of a cat in superposition of being dead and alive.

[Rev. Mod. Phys. 90, 025004] Published Thu May 31, 2018