Until recently, the von Neumann entropy and its generalizations (Renyi) were the principal quantitative characterizations of entanglement. A richer characterization, first developed here at Princeton, is becoming the tool of choice for investigating topological (and conventional) order in quantum ground states of condensed matter systems. A…

The plant kingdom is rich with examples of tissues, organs and entire organisms that uniquely showcase elegant mathematical and physical principles. These principles frequently reflect the interplay between functional necessity and developmental constraints. We discuss two examples that showcase how plants utilize intricate topological and…

The snail-shaped mammalian cochlea houses a narrow strip of sensory tissue that separates compartments of salty water. Sound stimulation launches a mechanical traveling wave down the cochlea that peaks in a tonotopic manner: high/low frequencies peak in the cochlear base/apex. Sensory hair cells respond to the motion with intracellular current…

A quantum system subject to the infinitely-strong measurement of textbook physics undergoes a discontinuous, random state collapse. All phase information in a superposition of the eigenstates of the measurement apparatus is then suddenly erased from the system under observation. However, in practice, measurements often involve a finite-strength,…

Many states of matter, including ferromagnets and superfluids, are ultimately described by a classical order parameter despite being composed of quantum particles. However, recent experiments have impelled us to look for new forms of emergence that are intrinsically quantum mechanical. These include topological insulators and quantum spin liquids…

Abstract: I will present our experimental work on Bose-Einstein condensates, systems of ultra-cold charge neutral atoms at a temperature of about 100 nano-Kelvin: one billion times colder than room temperature. These condensate—quantum gases—are nearly perfect quantum mechanical systems, and here we will demonstrate a technique by which these…

Abstract: From wildebeest herds to biological molecules and every scale in between, how individuals self-assemble into large, spatially complex groups is a key problem in understanding collective behavior, development, multicellularity, and cellular function. I will discuss recent measurements we have made that explore the molecular origin of…

Fermions, particles with half-integer spin such as electrons, protons and neutrons, are the building blocks of matter. When fermions strongly interact, complex behavior emerges that is often difficult to understand theoretically, for example in high-temperature superconductors, neutron stars or the quark-gluon plasma of the early universe. …

Abstract: ``We review recent breakthroughs in understanding some general features of the Renormalization Group and of Quantum Field Theory. We discuss some applications of these new results and their deep connection to the entanglement of the Quantum Field Theory vacuum.''

Jim Olsen On July 4 the CMS and ATLAS experiments operating at the Large Hadron Collider (LHC) near Geneva, Switzerland, announced the discovery of a new particle with a mass of 125 GeV. From its observed decay to two photons, we know this particle has intrinsic spin equal to 0 or 2, and must therefore be a boson. There is also strong…

By 2016 there is a good chance that the Advanced LIGO and VIRGO gravitational wave (GW) detectors, now in their final hardware upgrade phase, will have made the first direct detection of GWs, and regular detections will follow soon afterwards. These first events are likely to result from merging neutron stars, merging black holes, and possibly…

National and global energy challenges involve security, competitiveness, and reduction in environmental impacts. Yet structural factors in energy systems retard the pace of energy change. I will discuss the technology, policy, and economic levers that can be used to accelerate the pact of energy transformation

Insights from black hole physics and string theory suggest that gravity is an emergent phenomenon. The analogy between the Einstein equations and thermodynamics and the dualities between open en closed string theories give important clues towards the underlying mechanism. Motivated by our current understanding of M-theory, I propose a microscopic…

What do the laws of thermodynamics look like when applied to microscopic systems such as optically trapped colloidal particles, single molecules manipulated with laser tweezers, and biomolecular machines? In recent years it has become apparent that the fluctuations of small systems far from thermal equilibrium satisfy a number of strong and…

Building the most precise atomic clocks in the world by studying many-body physics About 60 years ago, the second was defined by the Earth’s rotation. However, with the discovery of quantum mechanics it became clear that atomic clocks could be significantly more accurate and more precise. Thus, in 1967 the second was redefined in terms of an…

"Measuring the Spins of Black Holes and Applying the Results"

Self-Assembly and Evolution of Color Producing Nanostructures of Birds and Insects In addition to molecular pigments, many organisms create colors for communication and camouflage using optical nanostructures. Color production by interference from thin films and diffraction gratings has been easily understood, but understanding color…