The Pleasure of Finding Things Out Deborah Berebichez, Ph.D. Optical Society of America July, 2009
Nov 13, 2014
The Pleasure of Finding Things Out
Deborah Berebichez, Ph.D.
Optical Society of America
July, 2009
"An honest man, the outstanding intuitionist of our age, and a prime example of what may lie in store for anyone who dares to follow the beat of a different drum" - Dr. Julian Schwinger
The ideal physics professor. Utterly brilliant and engaging, he was an inspiration.
Feynman, Photonics and Communications
“I find it odd when an introduction mentions that I
play the bongo drums it rarely finds it necessary to
mention that I also do theoretical physics. It shows that we have more respect
for the arts than for science.” Richard Feynman
Problem with science is that a lot of people don’t find it interesting or relevant
“Don't blindly accept the word of authority. Test it for yourself! And this is what science does. It tests and it tests again, and it doubts and it doubts—always.”
Feynman
Feynman’s Open Questions
“There is Plenty of Room at the Bottom” 1959 Feynman challenged physicists to write the entire Encyclopedia Brittanica on the head of a pin
He was predicting nanotechnology
Feynman examines Bill McLellan’s motor, 1960
Charles Dickens’ A Tale of Two Cities:12 characters per micron. (Stanford University)
We actually did it!
And the Story Continues…
The S U Hologram
Fabricating these tiny objects is not easy…
•Photonic crystals are periodic optical nanostructures that are designed to affect the motion of photons
•They work by affecting the propagation of electromagnetic waves (EM)
•Photons (waves) propagate through the structure - or not - depending on their wavelength. Wavelengths of light that are allowed to travel are known as models
What are Photonic Crystals?
•The repeating regions of high and low dielectric constants have to be of ~200 nm (blue) to 350 nm (red) . This makes the fabrication of optical photonic crystals cumbersome and complex.
•By making point defects in a photonic crystal, light can be localized, trapped in the defect.
Trapping Light in Photonic Crystals
Let me tell you why it matters…
Quantum computers will harness the power of atoms and molecules to perform memory and processing tasks 10X faster than silicon based ones
Recent research shows promise in trapping light in crystals to build waveguides, or to replace electron storage for computer logic
Modeling the trapping of light in crystals
Courant Institute, NYU and Department of Applied Physics and Applied Mathematics,
Columbia University
Let me tell you how we helped…
Optimization of Scattering ResonancesJournal of Mathematical OptimizationP. Heider D. Berebichez R.V. Kohn M.I. Weinstein
Simulating Physics with Computers
Physics is the act of modeling the world
Waves are everywhere!
More Waves: Communications
Wireless communications with desired usersStanford University
Time-Reversal for Focusing Waves
It is reversing the order in which a series of waves arrive at a defined position
It can compress signals and focus them on a desired target, ex: lithotripsy, targeted ads,
secure communications
WHAT IS TIME-REVERSAL?
WHY IS IT IMPORTANT?
Conventional waves disperse when traveling through a medium
Focusing waves has applications in several areas such as secure wireless communications
Communicating with time reversal
IMAGINE THE FOLLOWING SCENARIO…
Using time-reversal, when sending a secret message, the sender could ensure that only one location would receive the message. Interceptors at other locations would only pick up noise due to unfocused waves.
source
detector2.59m
2.4m
2.8m
Time Reversal explained
t0 T
T – t0
FWD phas
e
BWD phas
e
1 2
3 4
A picture of what happens in space
Spatial Focusing to within /2
Temporal Compressionof the Acoustic Waveto the Initial Pulse
The Two Main Results of TR
1.29 cmred: original
blue: after TR
From original =2.6 cm
From a State of Multiple Scattering…From Long Time-Dispersion…
With TR The Bit Stream is Recovered
We Recover the Bit Stream: { 0, 1, 1 }
-1 +1
+1
Recompressed signal after TR obtained at Rx
1.Spatial Focusing Only the Intended Receiver Gets the Message
2.Temporal Compression Bit Streams can be Recovered with Fidelity and Relatively Low Interference
Conclusions on TR Communications
Rx
Tx
TR works without line of sight
Message focuses at desired location
Experimental TR: Measurement locations
LOCATION A
LOCATION B
LOCATION C
1.2km
2.6km
2km
29 floors (5, 19, 28)
Balconies SW & NE
28 floors (19, 29)
7 floors (roof)
SECURE WIRELESS COMMUNICATIONS THAT REACH ONLY THE INTENDED RECEIVER AND CANNOT BE INTERCEPTED
COMMUNICATIONS IN INDOOR BUILDINGS (UWB)
Antisubmarine warfare and underwater communications that benefit from targeted signaling
UNDERWATER ACOUSTIC COMMUNICATIONS
IN THE BATTLEFIELD: LOCATING SOLDIERS AND FINDING TANKS IN
COMPLICATED FOLIAGE SCENARIOS
•Since spatial focusing can deliver focused energy at the intended receiver it can have applications also in homeland security and military communications. SPONSORS: NSF, ONR, DOE, DARPA, Intel UWB
But: People get discouraged at a young age to be analytical, scientific or
technologically oriented
Science is fun!
We can change that!
Why Now?
• We’re not growing enough scientists, especially compared to India and China
• The Problems that need solving need science: Energy, Climate, Genetics, Medicine, IT
• Good Citizens need to understand scientific issues to be informed, good voters
•Kid’s should be excited about science!
The Science of Everyday Life
It’s good to see a
coolWoman doing science
I want to study science and biology
-Ana, age 14
I enjoy being in the lab
thank you for showing me that A Woman
Can do Science
Ximena, age 16
Thank You for your Attention