---
title: 'Testing your intuition for quantum computing'
source: 'https://youtube.com/watch?v=XX8mjBXBqz8'
video_id: 'XX8mjBXBqz8'
date: 2026-08-08
duration_sec: 101
---

# Testing your intuition for quantum computing

> Source: [Testing your intuition for quantum computing](https://youtube.com/watch?v=XX8mjBXBqz8)

## Summary

This video presents a quiz designed to test the viewer's intuition about quantum computing, specifically how many queries are needed to find a marked item in an unstructured search. The host explains the classical approach, which takes O(N) time on average, and then challenges the audience to guess the quantum equivalent. The video also mentions a follow-up, full-length explainer on quantum computing fundamentals.

### Key Points

- **The Classical Search Problem** [00:00] — The video introduces a function that returns true for exactly one special input among the first N numbers. The only way to find it is by trying inputs one by one, which on average takes N/2 attempts, or O(N) in big-O notation.
- **The Quantum Question** [00:29] — The host poses the equivalent question for a quantum computer: given a function in a certain state, how many times would you need to use it to find the special input? The quiz options are O(√N), O(log N), O(log log N), and O(1).
- **Quiz Responses and Coherence** [00:56] — The host notes that the question is not coherent without specifying the context of quantum computing. They mention that responses from YouTube and other presentations varied, and they have created a full video explaining the quantum answer.
- **Answer and Full Video** [01:12] — The host directs viewers to jump to timestamp 3:50 for the quiz answer, and mentions that a half-hour explainer on quantum computing fundamentals, including a specific algorithm, is available for those who want a deeper dive.

### Conclusion

The video is a teaser that challenges the viewer's intuition about quantum computing, promising a detailed explanation in a follow-up video. It highlights the difference between classical and quantum search complexity, setting the stage for a deeper exploration of quantum algorithms.

## Transcript

Imagine I have a function and there's going to be one special number where if you input it to the function it returns true, but on all other inputs it returns false. And let's say you know that special input is somewhere among the first n numbers.
allowed to do with this function is to simply try it out on inputs, On average, this would take N halvesteps and following the CS convention
of disregarding constants like that 1/2 people would call this a runtime of big O of n. Now here's your for the equivalent version of this question. But in a quantum computer where you're given a function that is in a certain
how many times would you have to use this mystery function to be able to find I threw this quiz up as a YouTube post giving the options of O of square root of N,
O of log of N, O of log of log of N and O of one. would look like in that context, the question is not really coherent. In the responses on YouTube and also many other times that I've presented
I just put up a full video describing how quantum If you just want the answer to this quiz, you can jump to the timestamp 3:50.
content on your phone mood right now, but if at some point you want a half-hour explainer for the fundamentals of quantum computing walking you through a specific algorithm, well, that full video will be there waiting for you.