Ginzton Lab

AP483, Ginzton Lab, & AMO Seminar Series

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
• NYH, Phys. Rev. A 95, 012120 (2017). https://journals.aps.org/pra/abstract/10.1103/PhysRevA.95.012120
• NYH, Swingle, and Dressel, Phys. Rev. A 97, 042105 (2018). https://journals.aps.org/pra/abstract/10.1103/PhysRevA.97.042105
• NYH, Bartolotta, and Pollack, arXiv:1806.04147 (2018). https://arxiv.org/abs/1806.04147
• Gonzàlez Alonso, NYH, and Dressel, arXiv:1806.09637 (2018). https://arxiv.org/abs/1806.09637
• Swingle and NYH, Phys. Rev. A 97, 062113 (2018). https://journals.aps.org/pra/abstract/10.1103/PhysRevA.97.062113
• Dressel, Gonzàlez 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

AP483, Ginzton Lab, & AMO Seminar Series presents Conductivity of a perfect crystal

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.


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, October 29, 2018 - 4:15pm
Venue: 
Spilker 232

AP483, Ginzton Lab, & AMO Seminar Series

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.


 

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, October 22, 2018 - 4:15pm
Venue: 
Spilker 232

AP483, Ginzton Lab, & AMO Seminar Series presents Dynamic photonic structures

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.


 

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, October 15, 2018 - 4:15pm
Venue: 
Spilker 232

New Directions in Management Science & Engineering: A Brief History of the Virtual Lab

Topic: 
New Directions in Management Science & Engineering: A Brief History of the Virtual Lab
Abstract / Description: 

Lab experiments have long played an important role in behavioral science, in part because they allow for carefully designed tests of theory, and in part because randomized assignment facilitates identification of causal effects. At the same time, lab experiments have traditionally suffered from numerous constraints (e.g. short duration, small-scale, unrepresentative subjects, simplistic design, etc.) that limit their external validity. In this talk I describe how the web in general—and crowdsourcing sites like Amazon's Mechanical Turk in particular—allow researchers to create "virtual labs" in which they can conduct behavioral experiments of a scale, duration, and realism that far exceed what is possible in physical labs. To illustrate, I describe some recent experiments that showcase the advantages of virtual labs, as well as some of the limitations. I then discuss how this relatively new experimental capability may unfold in the future, along with some implications for social and behavioral science.

Date and Time: 
Thursday, March 16, 2017 - 12:15pm
Venue: 
Packard 101

Claude E. Shannon's 100th Birthday

Topic: 
Centennial year of the 'Father of the Information Age'
Abstract / Description: 

From UCLA Shannon Centennial Celebration website:

Claude Shannon was an American mathematician, electrical engineer, and cryptographer known as "the father of information theory". Shannon founded information theory and is perhaps equally well known for founding both digital computer and digital circuit design theory. Shannon also laid the foundations of cryptography and did basic work on code breaking and secure telecommunications.

 

Events taking place around the world are listed at IEEE Information Theory Society.

Date and Time: 
Saturday, April 30, 2016 - 12:00pm
Venue: 
N/A

Ginzton Lab / AMO Seminar

Topic: 
2D/3D Photonic Integration Technologies for Arbitrary Optical Waveform Generation in Temporal, Spectral, and Spatial Domains
Abstract / Description: 

Beginning Academic year 2015-2016, 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, February 29, 2016 - 4:15pm to 5:15pm
Venue: 
Spilker 232

Ginzton Lab / AMO Seminar

Topic: 
Silicon-Plus Photonics for Tomorrow's (Astronomically) Large-Scale Networks
Abstract / Description: 

Beginning Academic year 2015-2016, 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, February 22, 2016 - 4:15pm to 5:15pm
Venue: 
Spilker 232

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