School of Humanities and Sciences
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Sean Hartnoll
Associate Professor of Physics
BioI am a theorist working on problems in gravitational, high energy and condensed matter physics. In recent years the holographic correspondence, the physics of quantum entanglement and quantum field theory more generally have led to strong connections between central concerns in these different fields.
For example, I am interested in understanding the emergence of spacetime from large N matrix quantum mechanics models. These can be thought of as the simplest models of holographic duality, and will likely hold the key to understanding the emergence of local physics as well as black holes. The most basic object in these theories is the ground state wavefunction. Understanding this wavefunction is a manybody problem and I am interested in using modern ideas from condensed matter theory  such as topological order  to characterize it.
Another example has to do with dissipation. How quickly can a quantum mechanical system thermalize itself? From this perspective, there are remarkable similarities between strongly quantum mechanical systems such as the quarkgluon plasma and high temperature superconductors and the dynamics of black holes in classical gravity. This may suggest that a fundamental limitation imposed by quantum statistical mechanics is at work in these systems. I have pursued this possibility from many angles, including variational principles for entropy production, the LiebRobinson bound on velocities in quantum systems and bounds on the magnitude of quantum fluctuations near thermal equilibrium.
In parallel to a ''bird's eye'' approach to quantum statistical mechanics, I am also increasingly interested in specific scattering mechanisms in unconventional materials that may give a relatively simple explanation of transport behavior that has otherwise been considered anomalous  using this approach my collaborators and I have 'demystified' aspects of transport in quantum critical ruthenate materials. I am currently interested, for example, in the role of phonons in strongly correlated electronic systems.
I have recently worked on black hole interiors in classical gravity. Black hole interiors are extremely rich mathematically, but their physical interpretation  for example in a holographic context  remains obscure. To start to address this question I have shown how important dynamics of the interior, such as the instability of the singularity and of Cauchy horizons, can be triggered in a relatively simple holographic setting.
Lists of my publications and of recorded talks and lectures can be found following the links on the right. 
Patrick Hayden
Stanford Professor of Quantum Physics and Professor, by courtesy, of Computer Science
BioProfessor Hayden is a leader in the exciting new field of quantum information science. He has contributed greatly to our understanding of the absolute limits that quantum mechanics places on information processing, and how to exploit quantum effects for computing and other aspects of communication. He has also made some key insights on the relationship between black holes and information theory.

Leo Hollberg
Professor (Research) of Physics
BioHow can we make optimal use of quantum systems (atoms, lasers, and electronics) to test fundamental physics principles, enable precision measurements of spacetime and when feasible, develop useful devices, sensors, and instruments?
Professor Hollberg’s research objectives include high precision tests of fundamental physics as well as applications of laser physics and technology. This experimental program in laser/atomic physics focuses on highresolution spectroscopy of lasercooled and trapped atoms, nonlinear optical coherence effects in atoms, optical frequency combs, optical/microwave atomic clocks, and high sensitivity trace gas detection. Frequently this involves the study of laser noise and methods to circumvent measurement limitations, up to, and beyond, quantum limited optical detection. Technologies and tools utilized include frequencystabilized lasers and chipscale atomic devices. Based in the Hansen Experimental Physics Laboratory (HEPL), this research program has strong, synergistic, collaborative connections to the Stanford Center on Position Navigation and Time (SCPNT). Research directions are inspired by experience that deeper understanding of fundamental science is critical and vital in addressing realworld problems, for example in the environment, energy, and navigation. Amazing new technologies and devices enable experiments that test fundamental principles with high precision and sometimes lead to the development of better instruments and sensors. Ultrasensitive optical detection of atoms, monitoring of trace gases, isotopes, and chemicals can impact many fields. Results from welldesigned experiments teach us about the “realities” of nature, guide and inform, occasionally produce new discoveries, frequently surprise, and almost always generate new questions and perspectives.