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- Philipp Ludewig

My learnings of the quantum computing course

Aloha,

I can't believe that i would ever write these words, but i would like to share my learnings with you from the first lection of the "Pratical introduction to quantum computing" course. This was my first touching point with quantum computing and i am ecstatic that the CERN put together a series of lections to teach the basics of quantum computing. The best part of this is that these lections are free. Yes really, i was also astonished when i found this. The speaker for the first lection is Elías F. Combarro and this guy knows his turf. He got not only several degrees in Mathematics and Computer Science, he also wrote a lot scientific papers around topics such as Computability Theory, Machine Learning, Fuzzy Measures and Computational Algebra. I didn't join the Zoom call to be there and to ask questions but you could attend if you wanted too. I didn't find the link for that till now so i am just fine with the recordings.

The first big learning of the course for me was that quantum computers are not faster than classical computers but they need less resources for the same workload. There you can see the adverts work on you. All these IBM and big tech company blubber told me that quantum computer are so much better as they get the stuff done in no time. You know the shiny future stuff we all dream about. I am looking at you Elon. The thing is that after the first lection i still can't definitely describe how a quantum computer works next to a classical 'Von Neuman' machine but let me try:

A quantum computer operates with probability and repeats a dice roll several times. Qubits are these dices which can assume an infinite amount of states between 0 and 1 like real numbers. The quantum gate determines if the state of the qubit is the result we are looking for. The gate combined with the state has to be 1 to be the correct result. The key difference between a classical computing and the quantum computing is the repetetive way to determine a state and then calculating the correcteness of this state. The clasical computer would run a chain of steps to determine the result while all decisions can only be 0 or 1. Besides that a similarity is that the NP Problem cannot be solved by either computing models.

Please don't quote me on that. My understanding of the concept is still very rough. I will try this in the next post again till i am satisfied with it. Ok now some stuff i learned about QC. Yeh i will write it now in short as quantum computing(QC) is to long to keep up with.

The main part of a Quantum Circuit:

  • Data is the state of a Qubits
  • Operations are done with Quantum Gates
  • Results are determined by measurments and the gates

Have you ever heard of Heisenberg or the rule with the same name? The rule states that in the moment you measure the state of system you change it and with QC its the same. You can measure the state of qubit but you will also erase it. Which brings me to Quantum Gates(QG). Do i love these fancy names? Oh yes i do. After writing this post i will enjoy a QUANTUM BEER. In my time at the university i missed the course about compilers and still thats what was my first assumption about these QG.Theres X, NOT, Z gate(invert) and a H gate(Hadamard). The last one is to measure the state i guess? I am not sure what it was about. I wrote down that all of these gates are represented as a matrix.

That's it for now. I will need to do my homework another time and i will come back for an update. Check out the course till then and drop a comment. :)

PS: As a side note I relearned how to effectively take notes. Some months or years ago I read an official tutorial of the MIT or Harvard or Stanford or whatever one of these prestige universities on how to take notes properly. I followed the rules and had a pleasent result. Unfortunately i couldn't find a link or a mentioning on hackerNews about this. It's easily explained. You would prepare a page and divide it in three spaces. On the left would be a space for comments (1/5 of the page), in the middle is the main space for notes and on the bottom should be enough space for questions. You know these question which come up and doesn't get explained right away(more homework).