News & Events

Photo of Prof. Carlos Arguelles

The Department Welcomes a New Faculty Member: Carlos Argüelles

April 20, 2020

Carlos Argüelles is a neutrino physicist. His work explores properties of neutrinos using data from the IceCube Neutrino Observatory

The surprising discovery of neutrino mass and mixing leads to the obvious question: what other unexpected properties might neutrinos have? IceCube data provides a unique window on the highest energy neutrinos ever observed. It is an ideal place to search for new Beyond Standard Model effects.

The IceCube detector is buried in the Antarctic...

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Figure 1: a new refrigerator for molecules

Collisional Cooling of Ultracold Molecules

April 8, 2020
Fig. 1, right: A new refrigerator for molecules.  Sodium atoms (yellow spheres) collide with sodium-lithium molecules (combined-yellow-red spheres).  The atom-molecule mixture is trapped in an optical trap whose effective edge is shown as a white rim. As the trap is loosened (depicted as a dimmer rim), the most energetic sodium atoms leave the trap, providing evaporative cooling.  The cooling is transferred to the molecules via elastic collisions.  The frost on the molecules indicates that they...
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figure 1 from the article: Phase diagram of the 2D Rydberg Hamiltonian

Phases of a Two-Dimensional Rydberg Atom Array

March 31, 2020

The ability to fully control coherent quantum many-body systems is an exciting and rapidly developing frontier. Besides quantum information processing, controlled many-body systems can enable new insights into strongly correlated phases of matter. On this front, arrays of neutral atoms trapped in optical tweezers and interacting via controlled excitations into atomic Rydberg states provide an especially promising platform. In fact, their particular properties have allowed for the programmable realization and high-fidelity manipulation of a wide range of effective interacting spin models...

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Figure 1: Sample video, questions, and answers from our CoLlision Events for Video Representation and Reasoning (CLEVRER) dataset.

A Hybrid AI Model Lets It Reason about the World’s Physics Like a Child

March 6, 2020

A new data set reveals just how bad AI is at reasoning—and suggests that a new hybrid approach might be the best way forward.

Questions, questions: Known as CLEVRER, the data set consists of 20,000 short synthetic video clips and more than 300,000 question and answer pairings that reason about the events in the videos. Each video shows a simple world of toy objects that collide with one another following simulated physics. In one, a red rubber ball hits a blue rubber cylinder...

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Book cover for "The Second Kind of Impossible"

Harvard Science Book Talk: Paul Steinhardt, "The Second Kind of Impossible"

March 5, 2020

THE SECOND KIND OF IMPOSSIBLE tells one of the strangest scientific stories that you will ever hear – a thirty-five year quest for new forms of matter, known as quasicrystals, that violate scientific principles that had been established for centuries. The talk will describe the scientific odyssey that unfolds over the ensuing decades, first to prove the validity of the idea, and then to pursue Steinhardt's wildest conjecture: that nature made quasicrystals long before humans discovered them. Along the way, his team encounters clandestine collectors, corrupt scientists, secret...

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Schematic drawing of the resistivity of magic-angle graphene

Experiments on magic-angle graphene reveal a “strange metal” phase and transport behavior consistent with so-called Planckian dissipation

February 20, 2020

Magic-angle graphene captured the attention of condensed-matter physicists in 2018 when it was discovered that this material—made of two sheets of graphene with slightly misaligned lattice orientations—is a superconductor. Moreover, observations showed that the phase diagram of magic-angle graphene is similar to that of copper oxide high-temperature superconductors, with an insulating region next to a dome-shaped superconducting region. Now, Pablo Jarillo-Herrero from the Massachusetts Institute of Technology, Cambridge, and his colleagues report that magic-angle graphene...

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Photo of Prof. David Nelson

Nelson Awarded Niels Bohr Medal of Honour

December 10, 2019

Prof. David R. Nelson has been awarded the Niels Bohr Institute Medal of Honour for 2019. He is a world-renowned theoretical physicist of remarkable breadth and he has made seminal contributions to the field of statistical mechanics and what became known as soft condensed matter.

The Niels Bohr Institute Medal of Honour was established in 2010 to mark the 125th anniversary of Niels Bohr’s birth. The medal is awarded annually to a particularly outstanding researcher who is working in the spirit of Niels Bohr: International cooperation and exchange of knowledge.

To...

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A schematic figure of the quantum Rydberg central spin model. Credit: Ashida et al.

A New Theoretical Model to Capture Spin Dynamics in Rydberg Molecules

November 30, 2019

Rydberg molecules are giant molecules made up of tens or hundreds of atoms bound to a Rydberg atom. These molecules have a permanent dipole (i.e., a pair of oppositely charged or magnetized poles), as one of their atoms is in a highly excited state.

Physicists have been studying Rydberg molecules both theoretically and experimentally for several years. Most studies investigating these molecules, however, have only focused on situations that do not involve quantum spins, as the many-body nature of Rydberg molecules makes analyzing their spin dynamics particularly...

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