Quantum Entanglement - PowerPoint Presentation

Slide1

Quantum Entanglement

Modern Physics

5/10/11

Spring 2011

Ben Miller, Alexander

DeCarli

, Kevin ShawSlide2

What is it?Slide3

How do particles become Entangled?Slide4

Parametric Down Conversion

A laser (usually ultraviolet for its high frequency) sends a photon through a nonlinear crystal such as Beta Barium Borate

The photon bumps an electron to an excited state

When the electron comes back down and releases its photon, there is a chance it will split

If it splits, the two photons are equally half of the energy

These two photons are entangled

The overlapping of the cones represents the entanglement

The two photons are also polarized opposite of one anotherSlide5

Einstein called this "

Spooky

action at a distance."

Slide6

What is the “spookiness?”

Bell-state Quantum Eraser

The split photons are opposite in polarization

The double-slit selectively filter between polarizations (e.g. right slit allows clockwise)

A filter in front of Detector A for polarizations as well

If the A filter restricts the polarized light, then the polarization entering the double-slit is known and no interference

If the A filter allows all light, then polarization entering the double-slit is not known and interference shows up in both detectors.

How do photons at B know that polarization is no longer restricted at A?Slide7

History

Quantum Entanglement comes from the ERP paradox paper.

The paper was written by Albert Einstein, Nathan Rosen and Boris

Podosky

in 1935.

ERP is a topic in physics concerned with measuring and describing microscopic systems.

The three men felt that quantum mechanical theory was incomplete.

By incomplete, they were talking about entanglement but did not have a name for it.

Slide8

More History

Erwin Schrodinger read this paper and wrote to Einstein talking about the idea and called it “entanglement.”

Schrodinger later wrote a paper that defined the idea of entanglement.

Both Einstein and Schrodinger were dissatisfied with the idea.

In 1964 entanglement was tested and disproved by John Bell because it violated certain systems but since then other experiments have proved it to be true.

Each experiment had its flaws though. Slide9

Applications

Quantum Communication

Quantum Teleportation

Quantum Cryptography

A quantum system in an entangled state can be used as a quantum information channel to perform tasks that are faster than classical systems.Slide10

Macroscopic observation

Typically

, entanglement experiments involve entangling pairs of photons and observing the changes in one effecting the changes in the

other

Italian

physicists thought of an idea where the effects of entanglement could be easily

detected

A

pair of photons could be entangled and then separated. One of the photons could then be amplified into a shower of thousands of other photons, all entangled to the lone other

photon

Nicolas Gisin from the University of Geneva in Switzerland decided to test this with humans

.

The

beam of macro

photons

could be shown in one of two positions on a wall depending on the polarization of the lone microscopic photon, which defined the group

.

The

human tests were successful and matched with the results of a photon

detector

A

flaw was discovered in which detection of the photon would still occur after the entanglement connection was supposedly broken, suggesting a flaw in amplification and the inherent flaws in any

detector

This

flaw also hints that this particular experiment may not have been a micro-macro entanglement condition, but work is being done to enhance amplification with

lasers

Clearly

, humans can not be

usedSlide11

Communication

"

Superdense

coding"

We

typically use bits in

computer

processing, or in this case, classical bits

In

Quantum Mechanics, information can be stored using qubits, which describe a quantum state

Information

can be obtained via measurement of the

qubit

In

theory,

qubits

can contain other

dimensions

of information, but the predictability of determining information is only completely effective on a 1:1 scale of information from classical to quantum

This

means that effectively, a

qubit

can only reliable store as much as a classical bit

Useless

? Not with entanglement.

Qubits

can be entangled in pairs and therefore two classical bits per

qubit can be reached.

This

is a doubling of efficiency known as "

superdense coding"Slide12

Teleportation

- Has to do with transmitting a

qubit

from one location to another without the

qubit

being moved through free space

  - This can be used in the idea of a quantum computer, which would take advantage of changes in quantum states in order to rapidly send and process data

  - With the

qubit's

use of other dimension, more advanced algorithms can be used, in theory, to solve specific problems significantly faster and more effective than any classical computer

  - However, it is important to note that a classical computer can simulate a quantum one, therefore a quantum computer would not be able to solve a problem that a classical computer could not.  - Typically, qubits

are used to define and alter particle spinSlide13

Your Welcome

Ben Miller

Alexander

DeCarli

Kevin ShawSlide14

Sources

http://www.davidjarvis.ca/entanglement/quantum-entanglement.shtml

http://www.technologyreview.com/blog/arxiv/24797/

http://en.wikipedia.org/wiki/Quantum_entanglement

http://plato.stanford.edu/entries/qt-entangle/

http://www.blogcdn.com/www.engadget.com/media/2007/02/d-wave-quantum-2.jpg

http://discovermagazine.com/2007/may/quantum-leap/d-wave_processor2_lg.jpg

http://www.cpfreviews.com/Photon-Proton/DCP_5238_Proton_Beam_McKinl.jpg

http://lightzombies.com/store/images/Photon%20II%20Beam%20%20NVG.jpg

http://focus.aps.org/files/focus/v24/st11/freq_doubler.jpgSlide15

Article

on quantum entanglement at high temperatures.

http://www.technologyreview.com/blog/arxiv/24797/