The effect of applying Hadamard gates to multiple qubits is rather subtle and is used in many quantum algorithms. Consider $latex n$ input qubits, $latex |u_1 u_2 u_3 \cdots u_n\rangle$. What will be the output if we apply the Hadamard gate to each of the qubit? Note that a Hadamard gate maps $latex |0\rangle$ to…
It appears that YouTube occasionally hiccups on some ogv files and produces green screen. The following may not be the best solution. But it almost always solves the problem by first transcoding the video to avi. In linux, it can be done by mencoder as follows mencoder input.ogg -ovc xvid -oac mp3lame -xvidencopts pass=1 -o…
Let say Alice wants to pass her qubit to Bob. By no cloning theorem, we know that Alice cannot duplicate her qubit to Bob. However, she can “teleport” her qubit to Bob if they share a Bell state . First, Alice will apply CNOT gate from to her qubit in the shared Bell state. This…
I’m still studying the online course on quantum computing where Prof. Vazirani went through the no cloning theorem. It is very interesting to see that something that can lead to some very subtle consequence can also have a very simple proof. Below is a summary. Basically, the theorem states that no quantum state can be…
I have a JVC HD camcorder to video tape some presentations. The webcam is not bad but the AC in our room is just too noisy. As I mentioned in a previous post, one can easily remove noise using Audacity. However, the video from the my camcorder has the annoying MTS format. It took me…
I am studying the online class on quantum computing (coursera). I did a quantum mechanic course more than a decade ago but I didn’t go into the detail of the Bell’s experiment then. The explanation from Prof. Vazirani is great and I feel that I finally understand the setup after all these years! Here, I…
I am considering to buy an investment home recently and so am trying to really understand mortgage. As an engineer, I thought it should be very simple. Indeed, it is quite simple but it eventually spent me couple hours figuring it out on my own. It is a simple high school math problem but I…
Ubuntu has very convenient function to generate screencast. My favorite is gtk-recordMyDesktop. However, my mic isn’t very high quality and my screencast always ends up with annoying background noise. Actually, this noise can be easily removed by denoising tools such as Audacity. One just needs to exact the audio track, denoise it with Audacity, and…
There is an excellent article on how to resize an virtualbox disk.
This is something old. I “fixed” this several times and it happens again. I just include the solution here (original from this link) so that I don’t need to look for it again. $sudo chmod +s `which mount.cifs` ### <- that’s as a super user