### 12/01/2022: Prof. Nai Phuan Ong

TITLE: Berry Curvature effects in topological quantum matter

OVERVIEW: I will provide a simple introduction to the Chern number and Berry Curvature in crystalline solids. These topological features can result in surprising effects in transport experiments. A recent example is the planar thermal Hall conductivity observed in the Kitaev magnet a-RuCl_{3}.

### 10/28/2022: Prof. Cristiano Galbiati

TOPIC: Hunting for the invisible at LNGS (Laboratori Nazionali del Gran Sasso)

OVERVIEW: How the Princeton group managed to produce the first measurements of neutrinos the two complete cycles of fusion that powers the Sun and how they are planning to discover dark matter with two large apparatuses one mile underground.

### 4/8/2022: Prof. **Mihalis Dafermos**

TITLE: __Is classical physics deterministic?__

ABSTRACT: We are all taught that quantum mechanics suffers from lack of determinism. But classical, i.e. non-quantum, physics is supposedly deterministic: complete knowledge of initial conditions in the present uniquely determines the future. This notion of determinism is often associated with the name of Laplace and finds a mathematical realisation in the standard existence and uniqueness theorems for differential equations. But is it really true that the classical equals of mathematical physics uphold this notion? This talk will explore one of the most spectacular ways that Laplacian determinism can in fact fail.

This talk is hosted by PSPS and Math club.

### 3/18/2022: Prof. David Huse

Professor Huse’s work resides in the fields of quantum information and many-body physics. A few topics his work is based on include: measurement-induced phase transitions, many-body localization, and superconductivity. In his talk, Professor Huse will be talking about his current research. As an example, he will discuss a recent project he did with Professor Bakr’s, which you can read more about here: https://journals.aps.org/prx/pdf/10.1103/PhysRevX.10.011042

### 11/12/2021: Prof. Shinsei Ryu and Prof. Leslie Schoop

PSPS & PUCS Jointly Presents: From Quantum Theory to Quantum Materials

We are hosting a research talk this Friday, November 12th at 2 pm EST in Frist Multipurpose Room with Professor Shinsei Ryu and Professor Leslie Schoop in collaboration with Princeton University Chemical Society. Professor Shinsei Ryu’s talk will be about “Topological and dynamical phenomena in quantum many-body physics from the point of view of quantum entanglement” and Professor Leslie Schoop’s talk will be about “How principles from inorganic chemistry can be used to discover new quantum materials”.

### 9/30/2021: Prof. Juan Maldacena

TITLE: The various entropies of black holes, entanglement, and spacetime geometry.

ABSTRACT: In the 70’s, Bekenstein proposed that the entropy of a black hole should be proportional to its area. More recently a new formula for black hole entropy was proposed which depends on the geometry of the black hole interior. We will discuss them, and explain their implications for how we should view black holes in the full quantum theory of gravity.

### 4/29/2021: Prof. Lawrence Cheuk

TITLE: Laser cooling of molecules for quantum science

ABSTRACT: In the past few decades, tremendous progress has been made in controlling atoms. In particular, laser cooling of atoms have provided atomic samples at ultra cold temperatures, where quantum mechanics take center stage. This has opened up many applications ranging from precision tests of fundamental physics, realizing the most precise clocks ever made, and quantum simulation of idealized models of real materials. Compared to atoms, molecules provide additional features that provide new possibilities such as quantum simulation of a larger variety of quantum many-body Hamiltonians and new quantum information processing platforms using molecular qubits. Despite these promises, because of the additional degrees of freedom in molecules compared to atoms, they are much more challenging to control. In this talk, I will introduce a recent development in the field – laser cooling of molecules. I will discuss how this brings a similar level of control in molecules as has been achieved with atoms, and our plans on creating a new quantum science platform based on laser-cooled molecules in rearrangeable optical tweezer arrays.

### 4/10/2021: Prof. Silviu Pufu

There will be an exciting informal talk by Professor Silviu Pufu, reflecting on his journey through Princeton as an undergraduate, graduate student and finally Professor!

There will be time for interacting with Professor Pufu and asking him any questions you might have on his course of studies, his experience or Physics at Princeton in general.

**3/4/2021: Prof. Biao Lian**

**3/4/2021: Prof. Biao Lian**

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**2/15/2021: Prof. Sam Cohen, PPPL**

**2/15/2021: Prof. Sam Cohen, PPPL**

*via*the mainstream approach. In the last decade, based on the improved physics understanding, fusion reactor concepts, divergent from the mainstream, have emerged, ones suitable for a distributed power grid because they are compact. In this talk I shall describe one effort, the Princeton Field Reversed Configuration (PFRC), that explores a reactor designed to be relatively small and clean (low radioactivity). As such it would be suitable for a variety of applications including spacecraft propulsion and terrestrial power generation. The plasma physics of the PFRC strongly differs from that of the mainstream fusion reactor designs, hence is attractive and challenging.

**11/20/2020: Prof. Michael Romalis, PHY**

**11/20/2020: Prof. Michael Romalis, PHY**

**11/13/2020: Prof. Peter Meyers, PHY**

**11/13/2020: Prof. Peter Meyers, PHY**

**11/06/2020: Prof. Bob Austin, PHY**

**11/06/2020: Prof. Bob Austin, PHY**

**10/29/2020: Prof. Herman Verlinde, PHY**

**10/29/2020: Prof. Herman Verlinde, PHY**

**Black Holes, Firewalls and Quantum Computing**

**10/16/2020: Prof. Hakan Türeci, ELE**

**10/16/2020: Prof. Hakan Türeci, ELE**

**10/1/2020: Prof. **Dan Marlow, PHY

**10/1/2020: Prof.**Dan Marlow, PHY

TITLE: Galactic Exploration with Invisible Light

**9/24/2020: Prof. William Jones**, PHY

**9/24/2020: Prof. William Jones**, PHY

Title: Using the Universe as a Laboratory for Fundamental Physics; Observations of the Cosmic Microwave Background, and using clusters of galaxies to probe the nature of Dark Matter.

Abstract: I’ll discuss the ways in which we cosmologists use the Universe as a laboratory for probing fundamental physics that cannot be accessed in terrestrial labs. In particular, I’ll focus on activities in my lab, including i) the study of the statistical properties of the Cosmic Microwave Background – which can inform us about the constituents and evolution of our Universe, can probe theories of Cosmic Genesis, and have the potential to reveal a quantum theory of gravity, and ii) using measurements of the weak- and strong-gravitational lensing of galaxy clusters to probe the nature of dark matter, and the consistency of LCDM cosmologies at high- and low-redshift.

**9/17/2020: Prof. ****Jeff Thompson, ELE**

**Jeff Thompson, ELE**

TITLE: New platforms for quantum science with atoms

ABSTRACT: Atomic systems are at the frontier of many areas of quantum science and technology, including sensing and metrology, quantum simulation and quantum information processing. In this talk, I will present our work on developing novel atomic systems to advance these applications.

In the first part, I will discuss our work with rare earth atom defects in solid crystalline hosts, in particular Erbium (Er^{3+}). In comparison to color centers such as the NV center, rare earth atoms have a number of unique advantages including a high degree of isolation from the solid-state environment, telecom-wavelength photon emission and compatibility with a broad range of host materials. However, owing to their weak photon emission, individual Erbium atoms have never been directly observed. We overcome this challenge by engineering their optical transitions with silicon nanophotonic circuits. Based on this platform, we have demonstrated the first atomic source of single photons in the telecom band, as well as the first high-fidelity single-shot readout of an individual rare earth electron spin. Furthermore, we have demonstrated optical manipulation and single-shot readout of multiple atoms with spacings below the diffraction limit of light, using a novel frequency-domain super-resolution technique, which is promising for eventually manipulating dense atomic arrays with strong spin-spin interactions. Lastly, we have demonstrated reliable incorporation of Er^{3+} into several novel host crystals using ion implantation, including several with low magnetic noise from nuclear spins. These are promising steps towards realizing quantum technologies such as telecom-band quantum networks, as well as controllable, coherent strongly-interacting spin systems.

In the second part of my talk, I will discuss a new platform for laser-cooled atoms in optical tweezers based on Ytterbium (Yb). Alkali atoms in optical traps are a workhorse platform for quantum simulation, and recent work has shown that excitations to strongly-interacting Rydberg states can be used to realize controllable, high-fidelity quantum logic operations. We have extended these ideas to alkaline earth atoms, which should enable significantly improved performance through their unique electronic structure. I will discuss these ideas as well as the experimental approach we have used to create 144-site arrays of individually trapped Yb atoms. In addition, I will present novel spectroscopy of previously un-observed Yb Rydberg series, and recent results on Rydberg excitation of single Yb atoms in optical tweezers and trapping of Yb Rydberg states using the Yb^{+} ion core. I will conclude with an outlook towards implementing high-fidelity multi-qubit gates in the nuclear spins of ^{171}Yb, and if time permits, discuss prospects for a radically different approach based on circular Rydberg states.

**2/28/2020: Prof. Josh Winn, AST**

Title: The Transiting Exoplanet Survey Satellite

We all know that 8 planets — or maybe 9 — orbit the Sun. Did you

also know that astronomers have identified 4,000 planets orbiting

stars elsewhere in the Galaxy? Most of them were discovered by a

space telescope called Kepler that stopped operating last year. Now,

a new space telescope is continuing the search: the Transiting

Exoplanet Survey Satellite, or TESS. I will describe the reasons why

TESS was launched, and the results that have been achieved to date.

**2/14/2020: Prof. Andrew Leifer, NEU and PHY**

Title: Worm Brains: Neural dynamics and behavior of a small biological neural network

**11/15/2019: Prof. Igor Klebanov, PHY (Slides)**

**11/08/2019: ****Dr. Sabrina Pasterski (Slides)**

**11/05/2019 Prof. Salvatore Torquato, CHM (Slides)**

Title: Exotic Hyperuniform States of Matter

Abstract: Hyperuniform states of matter are characterized by an anomalous suppression of density fluctuations at large length scales [1,2]. Hyperuniform systems include all perfect crystals, perfect quasicrystals, and special disordered systems. Disordered hyperuniform many-particle systems are exotic amorphous states that reside at “inverted” critical points, which behave more like crystals in the manner in which they suppress large-scale density fluctuations, and yet are also like liquids and glasses because they are statistically isotropic structures with no Bragg peaks. Such singular amorphous states can be obtained via equilibrium or nonequilibrium routes, and come in both quantum-mechanical and classical varieties. Due to “hidden” order at large length scales, disordered hyperuniform materials are endowed with novel physical properties, including desirable photonic, transport and mechanical characteristics. I will provide an overview of the hyperuniformity concept and its generalizations. Topics covered include how optimal hyperuniform point configurations can be posed as energy-minimization problems; rank order of crystals, quasicrystals and disordered hyperuniform systems via a hyperuniformity index; classical ground states that are disordered, hyperuniform and highly degenerate; Fermionic point processes; zeros of the Riemann zeta function, and directional hyperuniformity. I will also discuss how the hyperuniformity concept motivated a recent study [3] that has uncovered previously unknown multiscale order in the prime numbers.1. S. Torquato and F. H. Stillinger, “Local Density Fluctuations, Hyperuniform Systems, and Order Metrics, Physical Review E, 68, 041113 1-25 (2003).2. S. Torquato, “Hyperuniform States of Matter,” Physics Reports,745, 1 (2018).3. S. Torquato, G. Zhang, and M. de Courcy-Ireland, “Hidden Multiscale Order in the Primes,” J. Physics A: Mathematicaland Theoretical, 52 135002 (2019).

**10/04/2019: Prof. Lyman Page, PHY**

**09/27/2019: Prof. Sanfeng Wu, PHY**

Title: 2D Quantum Matter: a platform for creating fundamentally new particles and future quantum devices

Abstract: In this talk, I will introduce the principle of emergence in physics and discuss its remarkable outcomes in condensed matter systems with several examples. I will then focus on describing the current experimental search for a kind of fundamentally new quantum particles, whose quantum property is distinct from all known elementary particles but allowed by the principle of emergence. This kind of particles could be used for storing and processing quantum information without decoherence.

**04/26/2019: Prof. Stanislav Shvartsman, CBE**

Title: Embryogenesis: a cascade of dynamical systems

Abstract: I will discuss our work on the design and experimental tests of mathematical models of embryogenesis. While the foundation of this research is based on models of isolated developmental events, the ultimate challenge is to formulate and understand dynamical systems encompassing multiple stages of development and multiple levels of regulation. These range from specific chemical reactions in single cells to coordinated dynamics of multiple cells during morphogenesis. Examples of our dynamical systems models of embryogenesis – from the events in the Drosophila egg to the early stages of gastrulation – will be presented. Each of these will demonstrate what had been learned from model analysis and model-driven experiments, and what further research directions are guided by these models.

**04/19/2019: Prof. Herman Verlinde, PHY**

Title: Black holes, Entropy and Quantum Chaos

Abstract: We now have direct observational evidence that black holes exist. However, there are still many things we do not know about them. What are black holes made of? What happens when you fall into a black hole? In this talk I will describe some recent insights into these questions, with special focus on the relation between black holes and quantum chaos, and more generally, between gravity and entropy.

**04/12/2019: Prof. Waseem Bakr, PHY**

Title: Quantum gas microscopy of ultracold fermions in optical lattices

Abstract: The normal state of high-temperature superconductors exhibits anomalous transport and spectral properties that are poorly understood. Cold atoms in optical lattices have been used to realize the celebrated Fermi-Hubbard model, widely believed to capture the essential physics of these materials. The recent development of fermionic quantum gas microscopes has enabled studying Hubbard systems with single-site resolution.

In this talk, I will describe experiments that use quantum gas microscopy to probe various phases of the Hubbard model. I will discuss site-resolved imaging of Mott insulators and antiferromagnets and transport measurements that reveal strange metallic behavior. Finally, I will describe our recent development of angle-resolved photoemission spectroscopy (ARPES) for Hubbard systems and its application to studying pseudogap physics in attractive Hubbard systems across the BEC-BCS crossover. This sets the stage for future studies of the pseudogap regime in repulsive Hubbard systems. (* RSVP*)

**04/05/2019: Prof. Mihalis Dafermos, MAT (Slides)**

Abstract: The celebrated “black hole” spacetimes of Schwarzschild and Kerr play a central role in our current understanding of Einstein’s general theory of relativity. Are these spacetimes stable, however, as solutions to the Einstein vacuum equations, in their exterior region? And what fate awaits physical observers who en- ter inside a “generic” black hole? It turns out that these two questions are intimately related and the answer to the second may be more disturbing than previously thought. This talk will try to explain how so.

**03/29/2019: Prof. Steven Gubser, PHY**

Title: 2-adic numbers and fast scrambling

Abstract: I will explain how a cold atom apparatus with sparse non-local interactions is expected to exhibit signs of fast scrambling. The fastest scrambling in this setup seems to occur halfway between a coupling pattern approximating linear geometry and a different one approximating 2-adic geometry.

**03/08/2019: Prof. Daniel Marlow, PHY**

Title: Physics at the Large Hadron Collider

Abstract:An overview of the current physics program at the LHC is given. The experiments are busy completing the analysis of data from LHC Run 2, which ran from 2015 through 2018, and preparing for the resumption of data taking in 2021. The large datasets being acquired will allow us to carry out precision studies of the properties of the Higgs boson and to search for signatures of new physics from beyond the standard model. The conceptual underpinnings of these analysis projects will be described. A key ingredient in any LHC physics analysis is the determination of the luminosity, which is a measure of how many proton-proton collisions have been observed. Techniques for measuring the luminosity will be discussed.

**03/01/2019: Prof. Howard Stone, PHY**

Title: The Dynamics of Complex Fluids: Intersections of biology, engineering, mathematics and physics.

Abstract: Prof. Stone will survey some research questions his group studies that utilize the principles of fluid mechanics (or soft condensed matter physics). He will try to highlight the way the experiments and theory can be used together to ask and answer new, timely research questions, especially that arise at the traditional boundaries of disciplines, and where the insights of physics are important.

**02/22/2019: Professor Neta Bahcall, AST**

Title: THE DARK SIDE OF THE UNIVERSE

Abstract: What is the Universe made of? Recent observations suggest surprising results: most of the content of the Universe is dark and unexpected; not only most of the matter in the Universe is dark and unconventional but, more surprisingly, the major component of the Universe may be in the form of ‘dark energy’ — a form of energy that opposes the pull of gravity and causes the expansion of the universe to accelerate. By combining recent observations of clusters and large-scale structure, distant supernovae, and the cosmic microwave background, we find evidence for a Universe that has only 5% normal baryonic matter, 20% non-baryonic dark matter, and 75% ‘dark energy’. The observations suggest a Universe that is lightweight, with only 25% of the critical mass-density needed to halt the Universal expansion; the Universe will likely expand forever. I will discuss the observations of the dark side of the Universe and their implications.

**2/14/19: Dr. Merritt Moore**

Title: Physics on Pointe – Navigating Physics and Dance with Merritt Moore

Abstract: Merritt Moore will discuss her journey as a physicist and professional ballet dancer. She will discuss why studying physics made her a better dancer, with a career spanning across the Zurich Ballet, Boston Ballet, English National Ballet, and Norwegian National Ballet, and why being a ballerina helped her graduate with a degree in physics from Harvard and with a PhD in Atomic and Laser Physics from Oxford.

Merritt was awarded Forbes 30 under 30 and featured in “Good Night Stories for Rebel Girls” Vol 2. She was one of the 12 selected astronaut candidates, out of thousands of applicants, to undergo rigorous astronaut selection on BBC Two “Astronauts: Do you have what it takes?”, and she continues to pursue the dream of becoming an astronaut, while pursuing a professional ballet and physics career. She will readily discuss all the “failures” and lessons she has learned along the way, share insights into the Quantum Optics research she pursued at Oxford, and perform a physics inspired piece.

**02/08/2019: Prof. Paul Steinhardt, PHY**

Title: The Second Kind of Impossible

Abstract: When is the impossible truly impossible, and when is it an opportunity for discovery? This talk will briefly discuss the improbable search for quasicrystals in the laboratory and in nature.

**11/30/2018: Prof. Claire Gmachl, ELE**

**11/16/2018: Prof. Roberto Car, CHM (Slides)**

Abstract: I will discuss how simulations allow us to solve complex many-body problems. I will discuss in particular two examples, one involving a realistic model of a non simple liquid (water) showing how we can compute its dielectric response (that involves correlation among molecular dipoles) and another example showing how simulations allow us to understand critical fluctuations in a simple Ising spin models

**09/28/2018: Prof. Frans Pretorius, PHY **(Slides)

Title: LIGO and the Extreme Side of Gravity (Slides)

**09/28/2018: Prof. Ravindra Bhatt, ELE**

Abstract: In this talk, I will trace the interplay of science and technology in the context of semiconductor heterostructures and the quantum-hall effect (QHE), culminating in the discovery of the fractional QHE, and unfolding of its complex, hierarchical structure. Following that, I will give an overview of the fascinating phenomena that QHE exemplifies. Finally, as time permits, I will briefly discuss some of the research in this field currently being pursued by several Princeton University groups as part of our unending quest to dig deeper into fundamental physics uncovered as a consequence of the surprising and unexpected discoveries made almost four decades ago.