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“ The saddest aspect of life right now is that science gathers knowledge faster than society gathers wisdom. ”
- Isaac Asimov
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Physics Conference Room, SB B326
Coffee starts at 12:00 PM and talk starts at 12:15 PM
11
Feb '19
Alireza Marandi  -  Monday, February 11, 2019
ABSTRACT: Our life in today’s fast evolving information age is tied to overwhelming technological challenges related to how we capture information on one hand, and, on the other, how we process it. Nonlinear photonic systems are among the growing technologies promising solutions for these challenges by offering paths toward efficient sensing systems for capturing information, and alternative computing platforms for processing it. One example of nonlinear optical processes is half-harmonic generation, which is splitting photons into pairs of photons at half the input frequency that happens in optical parametric oscillators (OPOs) at degeneracy; its intriguing characteristics such as intrinsic phase and frequency locking as well as possibility of generating quantum states of light have opened up unique opportunities for practical and scalable photonic techniques for molecular sensing and non-classical computing.
 
In this talk, I will overview the concept of half-harmonic generation and present the results of realizing efficient sources of femtosecond frequency combs in the mid-infrared based on it [1]. These coherent broadband sources in the molecular fingerprint region of the optical spectrum enable direct sensing of several molecular species simultaneously; a capability that has potential applications in areas such as analysis of greenhouse gases and medical breath analysis.
 
Moreover, I will discuss how half-harmonic generation has enabled development of a novel photonic computing platform, namely the optical Ising machine. Various combinatorial optimization problems in biology, medicine, wireless communications, artificial intelligence and social network that are not easily tractable on conventional computers can be mapped to the Ising problem, and hence the optical Ising machine offers a scalable path for tackling these problems. I will overview a sequence of experiments on development of these half-harmonic-generation-based Ising machines, from their first demonstration in 2014 [2], to a recent large-scale realization that can be programmed to arbitrary Ising problems [3], and one-to-one comparisons with the D-Wave quantum annealer. 
 
I will conclude the talk by presenting our ongoing work on chip-scale implementation of half-harmonic generation and paths toward quantum photonic engineering.
 
References:
[1] A. Marandi et al., Optica 3 (3), 324-327 (2016).
[2] A. Marandi et al., Nature Photonics 8 (12), 937-942 (2014).
[3] P. McMahon*, A. Marandi* et al., Science 354 (6312), 614-617 (2016)
25
Feb '19
Leonardo Ranzani  -  Monday, February 25, 2019
ABSTRACT: Parametric amplifiers increase the measurement fidelity of quantum circuits and are crucial to observe quantum phenomena at microwave as well as optical frequencies. The most common implementation of a lumped-element amplifier is a single nonlinear resonator driven on resonance by a strong electromagnetic pump. In this talk I am going to discuss a more general class of parametric devices consisting of multiple resonant modes coupled via parametric drives. By suitably controlling the amplitude and phases of different parametric processes we can effectively implement new system Hamiltonians, that provide different signal processing functions, such as nonreciprocal signal routing and directional amplification. I will also discuss an implementation of a superconducting multimode parametric circuit on a single chip that can be programmed in situ via a set of microwave drives.
25
Feb '19
David Tannor  -  Monday, February 25, 2019
PDFDownload PDF location309 Remsen Hall
12
Mar '19
Emil Prodan  -  Tuesday, March 12, 2019
18
Mar '19
Mariangela Lisanti  -  Monday, March 18, 2019
Dark matter in disequilibrium
Princeton University
1
Apr '19
Amir Arbabi  -  Monday, April 1, 2019
ABSTRACT: Miniaturized optical systems with planar form factors and low power consumption have many applications in wearable and mobile electronics, health monitoring devices, and as integral parts of medical and industrial equipment. Flat optical devices based on dielectric metasurfaces introduce a new approach for realization of such systems at low cost using conventional nanofabrication techniques. In this talk, I will present our work on dielectric metasurfaces that enable precise control of both polarization and phase with large transmission and high spatial resolution. Optical metasurface components such as MEMs tunable lenses, efficient wave plates, and components with novel functionalities will be discussed. I will also introduce a vertical on-chip integration platform enabled by cascading multiple metasurfaces and active optoelectronic components, and present optical systems such as cameras and spectrometers that have been implemented using this platform. This vertical integration scheme introduces a new architecture for the on-chip integration of conventional optical systems, and enables the unprecedented realization of massively parallel optical systems for computation, data storage, and biomedical sensing applications.
29
Apr '19
Matthew Sfeir  -  Monday, April 29, 2019
Manipulating exciton dynamics for energy conversion applications
Advance Science Research Center and Graduate Center, CUNY
6
May '19
German Kolmakov  -  Monday, May 6, 2019
ABSTRACT: In collaboration with Argonne National Lab (S. Gray, M. Otten, X. Ma), we studied the effects of quantum entanglement in two physical realizations of the excitonic systems: (a) plasmonically coupled quantum dots in an optical cavity and (b) quasi-two-dimensional CdSe/CdS nanoplatelets (NPLs).  Cavity quantum electrodynamics calculations show that upon optical excitation by a femtosecond laser pulse, entanglement of the quantum dot excitons occurs, and the time evolution of the g(2)  pair correlation function of the cavity photons is an indicator of the entanglement. We also show that the degree of entanglement is conserved during the time evolution of the system. Furthermore, if coupling of the photonic cavity and quantum dot modes is large enough, the quantum dot entanglement can be transferred to the cavity modes to increase the overall entanglement lifetime. This latter phenomenon can be viewed as a signature of entangled, long-lived quantum dot exciton-polariton formation. The preservation of total entanglement in the strong coupling limit of the cavity/quantum dot interactions suggests a novel means of entanglement storage and manipulation in high- quality optical cavities. We also find that, due to formation of biexcitons in an NPL and their subsequent decay, the emitted pairs of cavity photons are entangled at temperatures below 20 K. Under favorable conditions the photon pair can be nearly maximally entangled with the relative photon pair population ~0.5. Finally, we discuss possible experiments, in which the NPL generated photon pair entanglement can be observed, as well as potential applications in integrated quantum photonics.
13
May '19
Ana Asenjo-Garcia  -  Monday, May 13, 2019
16
Sep '19
Arkady Plotnitsky  -  Monday, September 16, 2019
ABSTRACT: Bohr never explained what he specifically meant, apart from the fact that complementarity reflects the fundamental difference between quantum physics and classical physics, based on the classical concepts of causality and determinism, closely connected to each other. This talk will introduce the concept of “quantum causality,” which divorces the idea of causality from determinism and explains why one may indeed be see complementarity in this way. This concept, however, is more general and allows one to offer a new perspective on the nature of quantum phenomena and the role of temporality and the arrow of time there, also in connection with quantum information theory, where similar conceptions of causality have been introduced in recent years in the work of C. Brukner, L. Hardy, and G. M. D’Ariano.
23
Sep '19
7
Oct '19
Paul Bourgade  -  Monday, October 7, 2019
ABSTRACT: I will survey properties of eigenstates of large random matrices, both in the Hermitian and non-Hermitian settings. In the Hermitian case, in the past few years universality of eigenvectors statistics (including delocalization) has been established, including for some models with short-range interactions. In the non-Hermitian case, our knowledge is much more limited so we will only consider the "integrable" Ginibre ensemble, exhibiting new statistics for the eigenvectors' overlaps.
21
Oct '19
Volker Sorger  -  Monday, October 21, 2019
ABSTRACT: Photonic technologies are at the forefront of the ongoing 4th industrial revolution of digitalization supporting applications such as virtual reality, autonomous vehicles, and electronic warfare. The development of integrated photonics in recent years enabled functional devices and circuits through miniaturization. However, fundamental challenges such as the weak light-matter integration have limited silicon and III-V-based devices to millimeter-scale footprints demanding about a million photons-per-bit.Overcoming these challenges, in the first part of this talk I will show how nanoscale photonics together with heterogeneous integration of emerging materials into foundry-based photonic chips enables strong nonlinearity, which we use to demonstrate attojoule and compact optoelectronics. Here I will discuss our recent devices demonstrating ITO-based MZI modulators, 2D-material excitonic photodetectors, and exotic epsilon-near-zero modes empowering record-efficient phase shifters for applications in data-comm, LiDAR, and photonic neural networks (NN). Further, I will show that the usually parasitic Kramers-Kronig relations of altering the optical index can be synergistically exploited delivering new modulator operations.

With Moore’s law and Dennard scaling now being limited by fundamental physics, the trend in processor heterogeneity suggests the possibility for special-purpose photonic processors such as NNs or RF-signal & image filtering. Here unique opportunities exist, for example, given by algorithmic parallelism of analog computing enabling non-iterative O(1) processors, thus opening prospects for distributed nonvan Neumann architectures. In the second part of this talk, I will share our latest work on analog photonic processors to include a) a feed-forward fully-connected NN, b) mirror symmetry perception via coincidence detection of spiking NNs, c) a Fourier-optics based convolutional processor with 1 PMAC/s throughputs at nanosecond-short delays for real-time processing, d) a photonic residue arithmetic adder, and e) mesh-based reconfigurable photonic & metatronic PDE solvers. In summary, heterogeneous photonics connects the worlds of electronics and optics, thus enabling new classes of efficient optoelectronics and analog processors by employing the distinctive properties of light.
28
Oct '19
Martin Bojowald  -  Monday, October 28, 2019
ABSTRACT: The big bang is often presented as the beginning of the universe. However, this statement, based on general relativity, follows from an extrapolation of the theory beyond its range of validity because it implies that the density and temperature of matter are infinite at the big bang.  Modern attempts to amend the theory by quantum space-time effects have led to alternative scenarios in which the universe may bounce back after a phase of collapse before the big bang. The physics involved, combining ultra-high density with abstract space-time properties, has not been constrained yet by observational tests, but it is subject to strong conceptual consistency conditions. This talk presents a possible physical picture of the big bang, based on several unexpected properties of space and time in quantum physics.
4
Nov '19
US/Middle East Conference on Photonics  -  Monday, November 4, 2019
Conference
ASRC - The Graduate Center, CUNY
PDFDownload PDF locationASRC Conference Room talk time9:00 am
ABSTRACT: This conference seeks to strengthen engagement between U.S., European, and Middle Eastern scientists by providing a forum for discussion of cutting edge photonics research.


Conference Outline

The conference will take place from Monday-Wednesday, November 4-6 at the Advanced Science Research Center (ASRC) on the campus of City College. Scientific sessions with invited talks will be held over the course of all three days.

On the first night of the conference (Monday, November 4), there will be a reception, early-career scientist symposium, and panel at The Graduate Center, CUNY:

Photonics 3.0: A Worldwide Quest for the Next Technology Revolution

6:30 p.m.

Participants: Nader Engheta (University of Pennsylvania), Mordechai Segev (Technion), and Federico Capasso (Harvard University).
Moderator: Andrea Alù (ASRC/The Graduate Center, CUNY)

Topics covered at the conference include:

› Metamaterials
› Topological insulators
› Biophotonics
› Plasmonics
› Nanooptics
› Integrated photonics
› Quantum optics
› Microwave photonics
› Random media
› Sensing
› Imaging
› Nonlinear optics
› Ultrafast spectroscopy
› Non-Hermitian photonics
11
Nov '19
Morrel Cohen  -  Monday, November 11, 2019
Looking back at seven decades in condensed matter physics
Rutgers University (Physics and Astronomy) and Princeton University (Chemistry and Chemical Biology)
ABSTRACT: I started research in solid state physics in 1950. I have witnessed it evolve into contemporary condensed matter physics over the ensuing seven decades. This talk focusses on several of the key events in the first three of those decades, the ‘50s, ‘60s, and ‘70s, that were fundamental to the emergence of many of the currently exciting areas active today. Being a theorist, I’ll emphasize the theoretical advances. Among those that I’ll of necessity touch on briefly are the introduction of topological reasoning, the growing role of spin-orbit coupling, explaining superconductivity, the discovery of disorder-induced localization, and the evolution of powerful electronic structure computation methods. Looking backward, 1950 was a time of great opportunity. Looking forward, 2019 is a time of even greater opportunity. Condensed matter physics has provided an excellent illustration of Vannevar Bush’s 1945 thesis “Science the Endless Frontier”.
18
Nov '19
Gabriele Grosso  -  Monday, November 18, 2019
2
Dec '19
Amir Ghetmiri  -  Monday, December 2, 2019
Si-based GeSn devices for mid-infrared optoelectronics
University of Arkansas at Pine Bluff
4
Dec '19
Mary Lanzerotti  -  Wednesday, December 4, 2019
PDFDownload PDF locationSB B326 coffee time12:00 pm talk time12:15 pm
ABSTRACT: This talk presents observations of the bursting of thick liquid films of molten steel following illumination of a thin vertical steel plate by a 1075-nm continuous-wave 1000W Ytterbium fiber. Molten steel formed in the illuminated region persists as a molten disk before a hole forms. Gravity is responsible for the formation of a dimple in the upper part of the molten disk and a bulge in the lower part. Images of the initial hole captured by a high-speed digital camera at room temperature conditions show that the hole enlargement is quite sudden, like a soap film popping. Following this, a single drop of molten forms and falls under the influence of gravity below the height of the laser beam, leaving behind a hole in the plate. Images of the initial hole captured by a high-speed digital camera show that the hole forms first in the top portion of the molten disk, not in the center.

The molten steel is modeled as liquid contained within a hoop with size of the final hole. 3D images produced by Surface Evolver, an interactive program for modelling liquid surfaces, indicate the presence of a dimple within the molten region near the location of first appearance of the hole, and a bulge in the molten region near the lower portion for a liquid with density and surface tension taking on values near the melting point of iron.