## SystemX Seminar presents The Promise of AR & New Challenges for Silicon

TBA

Topic:

The Promise of AR & New Challenges for Silicon

Abstract / Description:

TBA

Date and Time:

Thursday, October 25, 2018 - 4:30pm

Venue:

Huang 018

Topic:

Uncoupled isotonic regression and Wasserstein deconvolution

Abstract / Description:

Isotonic regression is a standard problem in shape-constrained estimation where the goal is to estimate an unknown nondecreasing regression function f from independent pairs (x_i,y_i) where đť”Ľ[y_i]=f(x_i), i=1,...n. While this problem is well understood both statistically and computationally, much less is known about its uncoupled counterpart where one is given only the unordered sets {x_1,...,x_n} and {y_1,...,y_n}. In this work, we leverage tools from optimal transport theory to derive minimax rates under weak moments conditions on y_i and to give an efficient algorithm achieving optimal rates. Both upper and lower bounds employ moment-matching arguments that are also pertinent to learning mixtures of distributions and deconvolution.

Date and Time:

Friday, October 26, 2018 - 1:15pm

Venue:

Packard 202

Topic:

Ten Arguments for Deleting Your Social Media Accounts Right Now and other thoughts about Internet

Abstract / Description:

TBA

Date and Time:

Wednesday, October 24, 2018 - 4:30pm

Venue:

Gates B03

Topic:

How to Build a Processor for Machine Learning

Abstract / Description:

Compute, data, and algorithms have combined to power the recent huge strides in machine intelligence. But there is still plenty of scope for improvement, and hardware is finally coming to the fore. Machine intelligence is the future of computing, so what needs to happen at a hardware level to make it faster and more energy- and cost-efficient?

This talk will outline the key considerations in how to build an efficient processor for machine intelligence both for today's state of the art networks and also to more rapidly and more flexibly support future innovations in algorithms and model structures.

Date and Time:

Tuesday, October 23, 2018 - 1:30pm

Venue:

Gates B12

Topic:

Quantum Electrodynamics of Superconducting Circuits

Abstract / Description:

The demand for rapid and high-fidelity execution of initialization, gate and read-out operations casts tight constraints on the accuracy of quantum electrodynamic modeling of superconducting integrated circuits. Attaining the required accuracies requires reconsidering our basic approach to the quantization of the electromagnetic field in a light-confining medium and the notion of normal modes. I will discuss a computational framework based on the Heisenberg-Langevin approach to address these fundamental questions. This framework allows the accurate determination of the quantum dynamics of a superconducting qubit in an arbitrarily complex electromagnetic environment, free of divergences that have plagued earlier approaches. I will also discuss the effectiveness of this computational approach in meeting the demands of present-day quantum computing research.

Academic year 2018-2019, please join us at Spilker room 232 every Monday afternoon from 4 pm for the AP 483 & Ginzton Lab, and AMO Seminar Series.

Refreshments begin at 4 pm, seminar at 4:15 pm.

Date and Time:

Monday, December 3, 2018 - 4:15pm

Venue:

Spilker 232

Topic:

TBA

Abstract / Description:

Academic year 2018-2019, please join us at Spilker room 232 every Monday afternoon from 4 pm for the AP 483 & Ginzton Lab, and AMO Seminar Series.

Refreshments begin at 4 pm, seminar at 4:15 pm.

Date and Time:

Monday, November 26, 2018 - 4:15pm

Venue:

Spilker 232

Topic:

When quantum-information scrambling met quasiprobabilities

Abstract / Description:

We do physics partially out of a drive to understand essences. One topic whose essence merits understanding is the out-of-time-ordered correlator (OTOC). The OTOC reflects quantum manybody thermalization, chaos, and scrambling (the spread of quantum information through manybody entanglement). The OTOC, I will show, equals an average over a quasiprobability distribution. A quasiprobability resembles a probability but can become negative and nonreal. Such nonclassical values can signal nonclassical physics. The OTOC quasiprobability has several applications: Experimentally, the quasiprobability points to a scheme for measuring the OTOC (via weak measurements, which refrain from disturbing the measured system much). The quasiprobability also signals false positives in attempts to measure scrambling of open systems. Theoretically, the quasiprobability links the OTOC to uncertainty relations, to nonequilibrium statistical mechanics, and more strongly to chaos. As coarse-graining the quasiprobability yields the OTOC, the quasiprobability forms the OTOC's essence.

*References*

â€˘ NYH, Phys. Rev. A 95, 012120 (2017). https://journals.aps.org/pra/abstract/10.1103/PhysRevA.95.012120

â€˘ NYH, Swingle, and Dressel, Phys. Rev. A 97, 042105 (2018). https://journals.aps.org/pra/abstract/10.1103/PhysRevA.97.042105

â€˘ NYH, Bartolotta, and Pollack, arXiv:1806.04147 (2018). https://arxiv.org/abs/1806.04147

â€˘ GonzĂ lez Alonso, NYH, and Dressel, arXiv:1806.09637 (2018). https://arxiv.org/abs/1806.09637

â€˘ Swingle and NYH, Phys. Rev. A 97, 062113 (2018). https://journals.aps.org/pra/abstract/10.1103/PhysRevA.97.062113

â€˘ Dressel, GonzĂ lez Alonso, Waegell, and NYH, Phys. Rev. A 98, 012132 (2018). https://journals.aps.org/pra/abstract/10.1103/PhysRevA.98.012132

Academic year 2018-2019, please join us at Spilker room 232 every Monday afternoon from 4 pm for the AP 483 & Ginzton Lab, and AMO Seminar Series.

Refreshments begin at 4 pm, seminar at 4:15 pm.

Date and Time:

Monday, November 12, 2018 - 4:15pm

Venue:

Spilker 232

Topic:

Conductivity of a perfect crystal

Abstract / Description:

Dissipation of electrical current in typical metals is due to scattering off material defects and phonons. But what if the material were a perfect crystal, and sufficiently stiff or cold to eliminate phonons -- would conductivity become infinite? We realize an analogous scenario with atomic fermions in a cubic optical lattice, and measure conductivity. The equivalent of Ohm's law for neutral particles gives conductivity as the ratio of particle current to the strength of an applied force. Our measurements are at non-zero frequency (since a trapping potential prevents dc current flow), giving the low-frequency spectrum of real and imaginary conductivity. Since our atoms carry no charge, we measure particle currents with in-situ microscopy, with which both on- and off-diagonal response is visible. Sum rules are used to relate the observed conductivity to thermodynamic properties such as kinetic energy. We explore the effect of lattice depth, temperature, interaction strength, and atom number on conductivity. Using a relaxation-time approximation, we extract the transport time, i.e., the relaxation rate of current through collisions. Returning to the initial question, we demonstrate that fermion-fermion collisions damp current since the lattice breaks Galilean invariance.

Refreshments begin at 4 pm, seminar at 4:15 pm.

Date and Time:

Monday, October 29, 2018 - 4:15pm

Venue:

Spilker 232

Topic:

New opportunities with old photonic materials

Abstract / Description:

Lithium niobate (LN) is an "old" material with many applications in optical and microwave technologies, owing to its unique properties that include large second order nonlinear susceptibility, large piezoelectric response, and wide optical transparency window. Conventional LN components, including modulators and periodically polled frequency converters, have been the workhorse of the optoelectronic industry. They are reaching their limits, however, as they rely on weakly guiding ion-diffusion defined optical waveguides in bulk LN crystal. I will discuss our efforts aimed at the development of integrated LN platform, featuring sub-wavelength scale light confinement and dense integration of optical and electrical components, that has the potential to revolutionize optical communication networks and microwave photonic systems, as well as enable realization of quantum photonic circuits. Good example is our recently demonstrated integrated LN electro-optic modulator that can be driven directly by a CMOS circuit, that supports data rates > 200 gigabits per second with > 90% optical transmission efficiency. I will also discuss our work on ultra-high Q LN optical cavities (Q ~ 10,000,000) and their applications, as well as nonlinear wavelength conversion using different approaches based on LN films.

Diamond is another "old" material with remarkable properties! It is transparent from the ultra-violet to infrared, has a high refractive index, strong optical nonlinearity and a wide variety of light-emitting defects of interest for quantum communication and computation. In my talk, I will summarize our efforts towards the development of integrated diamond quantum photonics platform aimed at realization of efficient photonic and phononic interfaces for diamond spin qubits.

Refreshments begin at 4 pm, seminar at 4:15 pm.

Date and Time:

Monday, October 22, 2018 - 4:15pm

Venue:

Spilker 232

Topic:

Dynamic photonic structures: non-reciprocity, gauge potential, and synthetic dimensions.

Abstract / Description:

We show that dynamic photonic structures, where refractive index of the structure is modulated as a function of time, offers a wide ranges of possibilities for exploration of physics and applications of light. In particular, dynamic photonic structures naturally break reciprocity. With proper design such photonic structure can then be used to achieve complete optical isolation and to completely reproduce magneto-optical effects without the use of gyrotropic materials. Moreover, the phase of the modulation corresponds to an effective magnetic gauge potential for photons, through which one can explore a wide variety of fundamental physics effects of synthetic magnetic field using photons. Finally, such dynamic photonic structure can be used to explore physics, especially topological physics, in dimensions that are higher than the physical dimension of the structure, leading to intriguing possibilities in manipulation of the frequencies of light in non-trivial ways.

Refreshments begin at 4 pm, seminar at 4:15 pm.

Date and Time:

Monday, October 15, 2018 - 4:15pm

Venue:

Spilker 232