Presentations

Basics

Importance of presentations

• Real world -- Often more important than: – quality of work done– importance of discovery or invention

• Major factor in:– salary– promotions– opportunities

Elements of technical presentations

• Must include sales pitch– Why should audience listen– Preferably also in title

• Must start out with excitement– All technical details come later

• Should be brief– Real-world -- 20 minutes is very long time

Sales pitch• Know your audience• Example -- presentation to boss

– find out background• highest degree, major, thesis title?• look up resume, publications, patents

– find out goals • examples: get rich quick, grow company

• Example -- presentation to customer– find out customer needs

• research details of customer business• past and current problems• anticipate future problems -- ex: competitors

Excitement

• Concentrate on important problem

• Example -- presentation to boss– sales trend over the past year

• Example -- presentation to customer– competitors latest advances

Technical details

• Describe new concepts by analogy– Example -- presentation to boss

• choose examples from boss’ field of expertise

– Example -- presentation to customer• choose examples from customers business

Detailed example• Presentation of design and performance of laser intensity servo• Audience: DVD manufacturer• Sales pitch:

– Want faster data rates? -- Use more stable laser.

• Excitement: – Ten-fold increase in data rate (projected)

• Technical details:– data rate limited by ability to recognize time-domain signal

– laser intensity noise:

» distorts signals, changes threshold levels, can give false signals

– laser intensity servo reduces noise by factor of 10 or more

» fixed data rate -- better bit error rate

» fixed bit error rate -- faster data rate

– project factor of 10 increase in data rate

• Choose title: Super-laser for ultra-fast DVD readout

Super-laser for ultra-fast DVD readout

• Stop!• Don’t put that noisy laser in your quiet DVD reader• Make your laser a “super-laser”

• Compatible with existing DVD designs• Field installable upgrade

Problem (including background info) • Fast DVD readout system

– discriminate among code words in a set

– faster than reading individual bits

– not simple threshold -- correlation

– intensity noise can distort

Code word recognition

idealactual

threshold

Resolved bits

ideal actual threshold

signal #1

intensitynoise

signal + noise

Compare to signal #2

Effects of intensity noise

signal #1

signal #2

Solution (note use of graphics)• Add-on intensity servo

• Suppresses noise factor of 10

• Ultra-high speed data

• Original noise prevents discrimination

• Reduced noise allows discrimination

High speed data

idealactual

Ultra high speed data

idealactual

Originalintensitynoise

Word #1

Word #2

Word #1

Word #2

Reducedintensitynoise

Design details (example customer knows)

• Put AOM in laser path• Undeflected beam:

– no change in alignment

– attenuated by increase in rf power

• Alternative: control current to laser diode– mode hops, frequency chirping ?

rf

reference

detector

Stable intensity

Laserdiode lens

DVD

readoutdetector

Back-scatter

deflectedAOM

Conclusion (take-away message)

• Super-laser performance w/o super laser– Add-on intensity servo

• Order or magnitude increase in data rate

• Field upgradable

• Technical details– exist, but not exciting

Second example

• Type II quantum computers– illustrated importance of inventing names

– audience will pay attention at least 3 min to find out what it means

– enough time for motivation

Type II quantum computing• Problem:

– Moore’s law in trouble• cannot continue to shrink existing technology

– But need Moore’s law to maintain superiority• commercial, military

• Solution:– See what a few atoms can do

• Scale up

– Quantum computing• Exponential speedup possible

Quantum computer types• Type I = standard quantum computer

– Shor’s, Grover’s, etc.

• Problem:– Must have 100’s of qubits to do anything real

– After 10 years -- experiments lucky to get 2• scalable design

– Will take too long to get to market• Technology area will die

• Solution:– Type II quantum computer

• Large array of small quantum computers (nodes)• Classical interconnects

– Even 2 qubits per node can do interesting problems• short-term product• upgradable -- each qubit per node doubles comp. power• directly scalable to Type I quantum computer

N QUBITS/NODE

M NODES

CLASSICALINTERCONNECTS

TYPE II QUANTUM COMPUTER

Implementation • Technical details

– Use spins in solids• Solid-state -- scalable

• Spins -- long lifetime

– Problem with spins • Isolated (long lifetime, difficult to excite)

– Solution -- use optical Raman dark states• Best of both worlds

– strong optical dipole coupling– no effect on spin lifetime

• Specifics– Use array of nitrogen-vacancy complexes in diamond (NV

diamond)

LASER ILLUM. LENS

PIXEL-REGISTEREDPHOTON COUNTER ARRAY

N-V ARRAY

Type II Q.C. in NV diamond

SAMPLEN-V DIAMOND ARRAY(J. MARTIN, ET.AL., APL 75, 1999)

Conclusion

• Type II Q.C. solves biggest problem w/ Q.C.– can get to market fast

• existing designs good enough to start

– can upgrade on qubit at a time (per node)

– can upgrade to Type I when technology ready

• Implement with NV diamond

Third example

• Ultra-slow and stopped light– illustrates importance of popular appeal

– applications existed, but foreshadowed by sci-fi factor• sounded like the impossible was now possible

Ultra-slow light

• Light speed: c = 186,000 mi/sec– strange things happen near v = c

• What if light moved at terrestrial speeds ?

• Light pulse slowed to speed of (racing) bicycle

Stopped light: Quantum storage• Moore’s law applies to memory too

– Memory will reach limit first: ~10YRS • Sign that the end is near

– Refrigerated hard drives• Quantum computers need memory

– Try running PC without RAM

MOORE’S LAW FOR INTEGRATED CIRCUITS

HARD DISK MEMORY BIT SPACING

Phy

sica

l spa

cing

, nm

100

10

1

Year 92 94 96 98 2000 02 04

Slow light basics• Group velocity is speed of information transfer

– Can be different than phase velocity

• Example: near steep refractive index dispersion– transparency has correct sign

PROBE DETUNING(arb. units)

0

0.5

1

AB

SO

RP

TIO

N

-0.5

0

0.5

RE

AL

PA

RT

of

Ultra-slow light in a solid

SIMPLIFIEDLEVEL DIAGRAM

17.3 MHz

10.2

4.64.8

±1/2

±1/2±3/2±5/2

±3/2

±5/2

3H4

1D2

COUPLING

PROBE

REPUMP

-1100%

0%

PR

OB

E T

RA

NS

.

PROBE DETUNING (MHz)-2 1 20

TRANSPARENCY

Pr: Y2SiO5

0 100 200 sec

Tra

nsm

itte

d P

robe

(%

)

0

12

Slowed lightIncomplete absorptionof probe

Input probe beam (x0.25)

SLOW LIGHT DEMO

• Delay = 100 sec = 33 m/s (70 mph)

Stopped light in a solid• Solid state material better for storage applications• Technical details:

– Control laser intensity determines light speed– Zero intensity stops the light pulse– Restore control laser to recover stopped light

Tra

nsm

issi

on (

%)

Delay Time (sec)3000 100 200 400

0

12

6Control laser

Slow light

Stopped light

Conclusion

• Ultra slow and stopped light– Works in a solid too

• Excellent potential for quantum storage