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Physics
Video: David Gross: The Coming Revolutions in Theoretical Physics
Talks about force theory of unification, string theory and supersymmetry. And easy and entertaining watch.
Physics
Gyro Cube that would that never needs Euler-ed
Notice the low speed wheels that do the balance compensation.
The Cubli is a 15 × 15 × 15 cm cube that can jump up and balance on its corner. Reaction wheels mounted on three faces of the cube rotate at high angular velocities and then brake suddenly, causing the Cubli to jump up. Once the Cubli has almost reached the corner stand up position, controlled motor torques are applied to make it balance on its corner. In addition to balancing, the motor torques can also be used to achieve a controlled fall such that the Cubli can be commanded to fall in any arbitrary direction. Combining these three abilities — jumping up, balancing, and controlled falling — the Cubli is able to 'walk'.
Lead Researchers: Gajamohan Mohanarajah and Raffaello D'Andrea
This work was done at the Institute for Dynamic Systems and Control, ETH Zurich, Switzerland and was funded in part by the Swiss National Science Foundation (SNSF),
Quantum-Mechanics
The transition from Classical to Quantum Mechanical Physics
The top diagram shows a collection of particles on the left side of a divider. If you imagine removing the divider the motion in aggregate is going to be described by a decaying exponential with a real term in the exponent.
The lower diagram shows the same setup with only one particle. Since we intend on looking at it in particular it is obvious that a decaying exponential will not be sufficient. Once the particle manages to travel from the left half of the divider to the right half of the divider it has the same level of chance to return to the left side. Thus it requires some sort of imaginary term in the exponential if we assume that diffusion still reigns as the mechanism of transport
In the Feynman lecture on physics there is a derivation of the Schrodinger wave equation that assumes difusion of the type in the second image.
Quantum-Computing
Two Bit Quantum Computer online
Research Links
Once you understand the simulation you can ask permission to use the real thing. I guess that that will not be necessary because the simulation does the same thing.
Quantum-Mechanics
Video: Quantum Field Theory plus Course materials
Lecture 01 – Introductory remarks on quantum field theory and classical field theory
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David Tong: Lectures on Quantum Field Theory
Video Lectures on Quantum Field Theory
These are videos of the lectures given at the Perimeter Institute PSI programme in 2009. Each video is in wmv format and somewhere around 130 Mb. More formats are available for download at the Perimeter Institute webpage here. http://pirsa.org/index.php?p=speaker&name=David_Tong
The lectures follow the printed notes which are available on the main quantum field theory webpage. http://www.damtp.cam.ac.uk/user/tong/qft.html
David Tong: Lectures on Quantum Field Theory
Video Lectures on Quantum Field Theory
These are videos of the lectures given at the Perimeter Institute PSI programme in 2009. Each video is in wmv format and somewhere around 130 Mb. More formats are available for download at the Perimeter Institute webpage here. http://pirsa.org/index.php?p=speaker&name=David_Tong
The lectures follow the printed notes which are available on the main quantum field theory webpage. http://www.damtp.cam.ac.uk/user/tong/qft.html
Quantum-Computing
Video: Quantum Computation simulations using Mathematica and Free Quantum Computing Add On
This calculations are available at: http://homepage.cem.itesm.mx/lgomez/quantum/v7phase.pdf
Shor's Factoring Algorithm is very important because it showed that a Quantum Computer will be more efficient than a normal computer when solving some important, practical problems (Factorization is important in the secure transmision of electronic data, like credit card numbers). This video shows briefly how Shor's algorithm can be simulated in Mathematica using the free Quantum add-on. Quantum is available at: http://homepage.cem.itesm.mx/lgomez/quantum/
Quantum-Mechanics
Double Quantum dots and electron spin control
The terminology makes it appear as if he is talking about a FET with source, drain and gate.
A lecture explaining Double Quantum Dots during the 2011 Undergraduate School on Experimental Quantum Information Processing (USEQIP) at the Institute for Quantum Computing.
Series of USEQIP 2011 series of videos
For more:
http://iqc.uwaterloo.ca/conferences/useqip2011
iqc.uwaterloo.ca
www.facebook.com/QuantumIQC
Twitter: @QuantumIQC
Physics
Video: Erann Gats explanation of quantum entanglement, measurement and interpretations
Using transmissive polarized sheets
Polarizer material experiment @ see 15:00 to 16:00 into the video below
—– 0 deg | —- 90 deg | = nothing comes out.
—– 45 deg | —– 0 deg | —– 90 deg | = ~nothing comes out. I am calling the leakage "0"
—– 0 deg | —– 90 deg | —– 45 deg | = ~nothing comes out.
—– 0 deg | —– 45 deg | —– 90 deg | = 1/4 intensity
1/4 intensity is due to electric field vector being diminished 2 times by square root of 2. Electric field is thus 1/2 and intensity will be the square of this at a value of 1/4.
Later in the talk Garrett uses a polarization rotator. This takes the output of one orthogonal polarizer and spins it 90 degrees so that it aligns with the second polarizer giving no relative loss to a single sheet of polarizer material. A single sheet of course has a loss of 1/2 when fed with unpolarized light. See image below.
David Mermin's "Stuff Left Behind" in terms of Von Neuman entropy.
It is highly recommend you watch David Mermin's "Stuff Left Behind" presentation before you watch this presentation. Mermin's work is like chapter 1 and this is like chapter 2.
Ron Garrett aka Erann Gat quantum video on quantum mechanics. It helps make quantum mechanics more clear by using very accessible experiments that use light as the test subject.
Research Links
- David Mermin's "Stuff Left Behind" presentation
- Erann Gat Website
- Ron-Garret-QM – local copy in case removes PDF version of the presentation done in 2001
- Quantum Eraser Experiment
- Double Slit Quantum Eraser – Walborn et al –
- Wikipedia: Von Neumann Entropy
- Local Copy: Quantum Mechanics of Measurement N. J. Cerf, C. Adami – Original location
- Quantum Entanglement of Photons demonstrated in relatively low cost set up – The presentation included here has simple explaination and experimental setup.
- Boojums All the Way Through is a collection of essays that presents the dilemma of communicating modern physics to both physicists and nonphysicists
- Home Made Quantum Eraser Experiment Using Laser 2 Slits Polarizer Material
- Two Slit Experiment with Quantum Eraser Realized with RF Components
Von Neumann Entropy
Where lambda are eigenvalues of the system. Very similar to Shannon entropy but I suppose with complex values.
Notes
- The polarizer experiments that he shows are quite interesting.
- This presentation builds on David Mermin presentation is like a second chapter to that
- The 3 particle correlation shown near the end is the David Mermin "Stuff Left Behind" presentation