quantum tunneling n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Quantum Tunneling PowerPoint Presentation
Download Presentation
Quantum Tunneling

Loading in 2 Seconds...

play fullscreen
1 / 24

Quantum Tunneling - PowerPoint PPT Presentation


  • 102 Views
  • Uploaded on

Quantum Tunneling. Free Wave Packet Tunneling through a Barrier Tunneling over a Well Example: Tunneling Microscope Tunnel Transistor a -particle decay. Quantum Tunneling. Postulates Maybe in lab. Quantum Tunneling. Time Dependent Wave Equation.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Quantum Tunneling' - rex


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
quantum tunneling

Quantum Tunneling

Free Wave Packet

Tunneling through a Barrier

Tunneling over a Well

Example: Tunneling Microscope

Tunnel Transistor

a-particle decay

quantum tunneling1
Quantum Tunneling

Postulates

Maybe in lab

quantum tunneling2
Quantum Tunneling

Time Dependent Wave Equation

What is the assumption Junior?

quantum tunneling3
Quantum Tunneling

Free Wave Packet in One Dimension

For one-dimension we have

Recall we make up a wave packet using Fourier analysis.

quantum tunneling4

E

E

Quantum Tunneling

Potential Step Barrier

The energy can be greater or less than the potential barrier.

E > U0

E < U0

quantum tunneling5

Lets first try to guess the wavefunction!

Quantum Tunneling

Potential Step Barrier

First we will consider E < U0

Region I U(x)=0

Region II U(x)=U0

Boundary Conditions

quantum tunneling6

but

Quantum Tunneling

E < U0

Potential Step Barrier

Reflection Coefficient

Transmission Coefficient

quantum tunneling7

Lets first try to guess the wavefunction!

Quantum Tunneling

Potential Step Barrier

Next we will consider E > U0

Region I U(x) = 0

Region II U(x) = U0

Boundary Conditions

quantum tunneling8
Quantum Tunneling

E < U0

Potential Step Barrier

Reflection Coefficient

Transmission Coefficient

quantum tunneling9

Lets first try to guess the wavefunction!

Quantum Tunneling

Potential Barrier for E < U0

Region I U(x) = 0

Region II U(x) = U0

Boundary Conditions

Region III U(x) = 0

quantum tunneling10
Quantum Tunneling

Potential Barrier E < U0

Solving these four equations

you find

quantum tunneling11
Quantum Tunneling

Wave Packet Impinging on A Step

Simulations

For E > U0

http://phet.colorado.edu/new/simulations/sims.php?sim=Quantum_Tunneling_and_Wave_Packets

quantum tunneling12
Quantum Tunneling

Tunneling Microscope

quantum tunneling13
Quantum Tunneling

Tunneling Microscope

quantum tunneling14
Quantum Tunneling

a-particle Decay

quantum tunneling15
Quantum Tunneling

Ammonia NH3 MASER

quantum tunneling16
Quantum Tunneling

Quantum Tunneling (Esaki) Diode

A tunnel diode or Esaki diode is a type of semiconductor diode which is capable of very fast operation, well into the microwave frequency region, by using quantum mechanical effects.

quantum tunneling17
Quantum Tunneling

Quantum Tunneling Transistor

Will replace MOPSET’s

ECE Headline News

High-speed signal mixer demonstrates capabilities of transistor laser

By James E. Kloeppel, U of I News BureauMarch 26, 2009

Single electron transistor (SET)

quantum tunneling18
Quantum Tunneling

Scattering: Potential Well E > U0

50 eV

Lets guess the wavefunction!

Lets look at the simulation.

Is this a homework problem?

quantum tunneling19
Quantum Tunneling

Next time…..

What if the potential is ?

…. called the finite square well.

quantum tunneling20
Quantum Tunneling

Simulations

A great Java tunneling simulation

http://phet.colorado.edu/new/simulations/sims.php?sim=Quantum_Tunneling_and_Wave_Packets

Have file phet tunneling????

Also has good tunneling simulations

http://www.cs.unm.edu/~dstrain/sem/results.html

http://phys.educ.ksu.edu/vqm/html/qtunneling.html

quantum tunneling23

P2(As2)

TMIn

50nm

0.6 eV

Ec

InP

InP

InAs

InAs

InAs

Quantum Tunneling

Growth via Chemical Beam Epitaxy (CBE)

A contacted InAs/InP nanowire

Quantum Dots: Harvard Wire Research

InAs/InP Heterostructured Nanowires

Energy landscape

TEM photo of InAs/InP nanowire