Laser-cooled and trapped atomic ions are standards for quantum information science, acting as qubits with unsurpassed levels of quantum coherence while also allowing near-perfect measurement. When qubit state-dependent optical forces are applied to a collection of ions, their Coulomb interaction is modulated in a way that allows entanglement…

Within the past year and a half we have lost Val Fitch and Jim Cronin, two of Princeton’s greatest physicists. Their 1964 discovery of CP Violation in the decays of the long-lived neutral K meson, referred to at the time as “the Princeton Effect,” was a complete surprise, right out of the blue, that defied any and all explanation. The mystery…

The statistical mechanics of equilibrium systems is characterized by two fundamental ideas: that closed systems approach a late time thermal state and that of phase structure wherein such late time states exhibit singular changes as various parameters characterizing the system are changed. Recent progress has established generalizations of…

The laws of quantum mechanics have been known for nearly a century, and have passed every test that has been made of them. But knowing them does not mean that we understand all that they permit. Einstein noticed that a key prediction of quantum mechanics is that it permits states with what is now called long-range “entanglement;” in his …

The search for dark matter is among the most challenging in particle physics, because even the question of how to look for it relies on an idea of what it is. The past decade has brought tremendous new data constraining the most popular scenario - the Weakly Interacting Massive Particle or WIMP. We will consider the implications for this new…

*Please note this colloquium starts at 4:30 p.m.* The quantum Hall effect, discovered 35 years ago, is a bizarre phenomenon in which a 2D gapped system can nevertheless carry a current. Moreover, the transverse conductivity of the system is precisely quantized in units of e^2/h. Unfortunately, this behavior requires a strong perpendicular…

One hallmark of chaos is sensitive dependence to initial conditions, the “butterfly effect.” We will discuss recent advances in our understanding of the quantum butterfly effect and its connection to the quantum physics of black holes. We will discuss a universal bound on the rate of development of quantum chaos motivated by these developments…

With quantum gas microscopy we are now able to take the control of ultracold quantum gases in an optical lattice to the next and ultimate level of high fidelity addressing, manipulation and readout of single particles. In my talk I will first give an introduction to this field of research and present an overview of recent experiments. I will…

After 50 years, the gravitational radiation community announced the detection of a binary black hole merger. The radiation traveled through space for a billion years and registered in the LIGO interferometers on Sep. 14. I will describe what really went on in the few years before the detection, what the prospect is for getting daily black hole…

In this talk I will describe the recent detection of gravitational waves by the LIGO/Virgo collaboration. The main event heard, GW150914, is consistent with the emission of gravitational waves from the late inspiral, merger and ringdown of two heavy stellar mass black holes. Many aspects of this event are fortuitous and remarkable, and I will…

Non-zero neutrino mass brings with it new complexity in the neutrino sector, and major questions surrounding neutrino masses and mixing remain unanswered. Among the unknowns are the ordering of the neutrino masses, key details of flavor mixing, and whether neutrinos respect CP symmetry. NOvA, a long-baseline neutrino oscillation experiment…

A very close supernova explosion could have caused a mass extinction of life in Earth. In 1996, Brian Fields, the late Dave Schramm, and the speaker proposed looking for unstable isotopes such as Iron 60 that could have been deposited by a recent nearby supernova explosion. A group from the Technical University of Munich has discovered Iron 60…

Microscopy has played important roles in revealing new insight in diverse fields of research ranging from physics to biology. It likewise is an important component of controlling nano-scale structures in the semiconductor industry. I will trace my own path of adapting various forms of scanned probe microscopy to image vortices, electrons, and…

Friction is the basic, ubiquitous mechanical interaction between two surfaces that results in resistance to motion and energy dissipation. To test long-standing atomistic models of friction processes at the nanoscale, we have implemented a synthetic nanofriction interface using laser cooled ions subject to the periodic potential of an optical…

In specially designed solid microcavities, the photon properties can be altered to have effective mass and repulsive interactions; these new states are called "polaritons". The polaritons act like atoms, and because they are bosons, they can undergo Bose-Einstein condensation. The experiments on polariton condensation have shown truly…

Starting with the discovery of graphene, the Dirac equation has appeared in many different contexts in condensed matter physics. In this talk I will describe two recent developments: the effects of chiral anomalies in Weyl and Dirac materials, and the Dirac nature of the composite fermion in the many-body physics of the half-filled Landau…

Cosmic-ray antiprotons have been a valuable tool for dark matter searches since the 1970s. Recent years have seen increased theoretical and experimental effort towards the first-ever detection of cosmic-ray antideuterons, in particular as an indirect signature of dark matter annihilation or decay in the Galactic halo. In contrast to other…

A longstanding goal of violin research has been to establish objectively measurable parameters for violin quality. These would presumably substantiate one of the violin-world’s most passionately held beliefs: Violins made by Stradivari and his contemporaries in 18th Century Italy sound better than any made elsewhere or since. However, a team…

The colloquium talk that was scheduled for Thursday, Feb. 18 has been cancelled.
 

The importance of determining and interpreting the structures of atoms, crystals, and proteins was established long ago. I will discuss current efforts to extend this paradigm to the brain, focusing on new discoveries concerning the structure of the retina gained through 3D electron microscopy, computer vision, and crowdsourcing. I will also…