Quantum Logic Q&A for EngineersThis is an active QC simulator, which provides a programming interface, as well as a programmer's visual model, for QC operations. It's not finished yet, but you're welcome to browse. Please give feedback to qc@machinelevel.com!©20002016 All rights reserved. For more information, please send email to qc@machinelevel.com 
1.1 Quantum Coins Here's a program which flips any number of (nonentangled) quantum coins, and prints the result. (When you run the program, a set of quantum logic gates should be constructed, along with a circlechart which shows the probability of different states in the quantum system. It's more important to play with these than to understand them at this point.) Things to try:


(You can also just use shiftenter in the code window)  
output: 

(You can also just use shiftenter in the code window)  
More things to try:



1.2 Quantum Entangled Coins Here's a program which demonstrates entanglement of two qubits. Try this:



output: 

Here's the same thing, but where the qubits are read at different times. 


output: 


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More Reading:



1.5 Preselecting Basis In the paper this question is originally about, my understanding is that one of the things they're trying is preselecting the measurement basis. Coins won't actually help understand this, but polarized photons will. I should insert a discussion here about photon polarization, but am about out of time, so here's the scrappy version: Choosing the 'basis' in this case refers to whether or not you hold the polarizing filter by 45 degrees. If I send you a verticallypolarized photon, and put it through a vertical filter, it'll get through. If you rotate your filter by 45 degrees, you'll get a random bit, because it'll have a 50/50 chance of getting through. ...so unlike a coin toss where we can only ask one question, real quantum states give us the ability to choose which question we ask. By randomly preselecting the basis (before outside of the entanglement's light cone), the experiment attempts to show that then entangling event couldn't have encoded enough information to produce the entangled results classically. Note: This is just my rough quicksketch interpretation of the general gist of this experiment. It's not exhaustive, or even correct. Still, it's fun. Try this:



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That's it for this one. If you've got more questions or feedback, please send them on to me at qc@machinelevel.com.  ej 