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Physics Conference Room, SB B326
Coffee starts at 12:00 PM and talk starts at 12:15 PM
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.
[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)
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.
Feb '19
David Tannor  -  Monday, February 25, 2019
PDFDownload PDF location309 Remsen Hall
Mar '19
Emil Prodan  -  Tuesday, March 12, 2019
Mar '19
Mariangela Lisanti  -  Monday, March 18, 2019
Dark matter in disequilibrium
Princeton University
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.
Apr '19
Matthew Sfeir  -  Monday, April 29, 2019
Manipulating exciton dynamics for energy conversion applications
Advance Science Research Center and Graduate Center, CUNY
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.
May '19
Ana Asenjo-Garcia  -  Monday, May 13, 2019
Sep '19
Oct '19
Paul Bourgade  -  Monday, October 7, 2019
Oct '19
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.
Oct '19
Martin Bojowald  -  Monday, October 28, 2019
Penn Stae
Nov '19
Morrel Cohen  -  Monday, November 11, 2019
Nov '19
Gabriele Grosso  -  Monday, November 18, 2019
Dec '19
Shy Shoham  -  Monday, December 9, 2019
NYU, Langone