NYU Arts & Science
Physics Colloquia
February 1, 2018 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Andrew de Gouvea
Northwestern University

TBA



February 8, 2018 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Amir Yacoby
Harvard University

A New Spin on Superconductivity

Nearly a hundred years after its discovery, superconductivity remains one of the most intriguing phases of matter. In 1957 Bardeen, Cooper and Schrieffer (BCS) presented their theory of superconductivity describing this state in terms of pairs of electrons arranged in a spatially isotropic wave function with no net momentum and a spin singlet configuration. Immediately thereafter, a search began to find materials with unconventional superconductivity where pairing deviates from conventional BCS theory. One particular class of unconventional superconductors involves pairs arranged in triplet rather than singlet configurations. Such superconductors may enable dissipationless transport of spin and may also give rise to elementary excitations that do not obey the conventional Fermi or Bose statistics but rather have non-Abelian statistics where the exchange of two particles transforms the state of the system into a new quantum mechanical state. In this talk I will describe some of our recent work that explores the proximity effect between a conventional superconductor and a semiconductor with strong spin-orbit interaction. Using supercurrent interference, we show that we can tune the induced superconductivity continuously from conventional to unconventional that is from singlet to triplet. Our results open up new possibilities for exploring unconventional superconductivity as well as provide an exciting new pathway for exploring non-Abelian excitation.


February 22, 2018 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Katharina Ribbeck
MIT

TBA



March 1, 2018 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Paul McEuen
Cornell

The Future of Small

Fifty years ago, the Nobel Prize-winning physicist Richard Feynman claimed that a revolution was underway where information, computers, and machines would be shrunk to impossibly small dimensions. History has proven him mostly right: Moore’s law has brought Feynman’s dreams to fruition in the realms of data and computing, giving us cell phones, the internet, and artificial intelligence. But the third leg of Feynman’s dream, the miniaturization of machines, is only just getting underway. Can we create functional, intelligent machines at the smallest scales? And if so, how? In this talk, I’ll take a look at some of the approaches being explored, including our group’s forays into combining electronics, paper arts, and functional 2D materials to create a new generation of smart, active micromachines.


March 22, 2018 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Steven Gubser
Princeton University

TBA



March 29, 2018 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Leslie Atkins Elliott
Bosie State University

TBA



April 5, 2018 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Massimiliano Di Ventra
University of California, San Diego

MemComputing: A Brain-inspired Topological Computing Paradigm

Which features make the brain such a powerful and energy-efficient computing machine? Can we reproduce them in the solid state, and if so, what type of computing paradigm would we obtain? I will show that a machine that uses memory to both process and store information, like our brain, and is endowed with intrinsic parallelism and information overhead - namely takes advantage, via its collective state, of the network topology related to the problem - has a computational power far beyond our standard digital computers [1]. We have named this novel computing paradigm “memcomputing” [2, 3]. As examples, I will show the polynomial-time solution of prime factorization, the search version of the subset-sum problem, and approximations to the Max-SAT beyond the inapproximability limit using polynomial resources and self-organizing logic gates, namely gates that self-organize to satisfy their logical proposition [4]. I will also demonstrate that these machines are described by a Witten-type topological field theory, and they compute via an instantonic phase, implying that they are robust against noise and disorder [5]. The digital memcomputing machines that we propose can be efficiently simulated, are scalable and can be easily realized with available nanotechnology components, and may help reveal aspects of computation of the brain.

[1] F. L. Traversa and M. Di Ventra, Universal Memcomputing Machines, IEEE Transactions on Neural Networks and Learning Systems 26, 2702 (2015).
[2] M. Di Ventra and Y.V. Pershin, Computing: the Parallel Approach, Nature Physics 9, 200 (2013).
[3] M. Di Ventra and Y.V. Pershin, Just add memory, Scientific American 312, 56 (2015).
[4] F. L. Traversa and M. Di Ventra, Polynomial-time solution of prime factorization and NP-complete problems with digital memcomputing machines, Chaos: An Interdisciplinary Journal of Nonlinear Science 27, 023107 (2017).
[5] M. Di Ventra, F. L. Traversa and I.V. Ovchinnikov, Topological field theory and computing with instantons, Annalen der Physik 1700123 (2017).



April 12, 2018 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Steve Girvin
Yale University

Schrödinger Cats, Maxwell’s Demon and Quantum Error Correction

A ‘second quantum revolution’ is underway based on our new understanding of how information can be stored and manipulated using quantum hardware. Even more remarkable than the concept of quantum computation is the concept of quantum error correction. We know that measurement disturbs a quantum state. Nevertheless, it is possible to store an unknown quantum state and if it develops errors due to imperfect hardware, we can measure and correct such errors to recover the original (and still unknown) quantum information. Recent experiments at Yale have successfully demonstrated quantum error correction that reaches the break-even point for the first time in any platform. This talk will present an elementary introduction to the field as well as an overview of recent experimental progress.
Reference: ‘Extending the lifetime of a quantum bit with error correction in superconducting circuits,' Nissim Ofek, et al., Nature 536, 441445 (2016).


April 19, 2018 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Vicky Kalogera
Northwestern University

TBA



April 26, 2018 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Andrew Geraci
Northwestern University

TBA



May 3, 2018 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Priyamvada Natarajan
Yale University

TBA