If you want to really make your application stand out, you could try reading this book and then simulating a basic quantum computer. There’s a good YT video of the same name, which is a better introduction to the topic. I can DM you my own project if you want to have a look :)
I haven't entirely read this book, but I remember that it explains Grover's algorithm well. It might be what you are looking for because it states that it's target audience is undergraduate computer science students.
Don't get discouraged, it's possible to get to a reasonable understanding with some sustained effort. However, you need to get the following into your head as quickly as possible:
Popular level explanations of anything quantum are a waste of your time.
Go back and read that again. You will never get close to understanding the field if you rely on someone else managing to "find the right metaphors" for you. Quantum computing is a mathematical field, and if you want to understand a mathematical field, you need to do mathematics. This sounds super scary, but it's actually no problem! Math is not what you think it is, and is actually a lot of fun to learn. You just need to put some work in. This just means maybe doing an hour or so of learning every day before you go to work, or afterwards.
Let's look at a little bit of a roadmap that you can follow to get to a reasonable understanding of quantum computing / quantum information. This is pretty much the path I followed, and now I am just about to submit my PhD thesis on quantum computational complexity. So I guess it worked out OK.
1) You can get really far in quantum computing with some basic understanding of linear algebra. Go to Khan Academy and watch their fantastic introduction.
If Sal asks you to do an exercise, do the exercise.
2) Now you know what a vector is, can kind of grasp what a vector space is, and have some good intuition on how matrix-vector and matrix-matrix multiplication works, then you can probably make a reasonable start on this great intro book: https://www.amazon.co.uk/Quantum-Computing-Computer-Scientists-Yanofsky/dp/0521879965
Start from the start, take it slowly, and do all of the exercises. Not some of the exercises, do all of the exercises. If you don't know a term, then look it up on wikipedia. If you can't do an exercise, look up similar ideas on Google and see if you can muddle your way through. You need to get good at not being scared of mathematics, and just pushing through and getting to an answer. If there is an explanation that you don't understand, look up that concept and see if you can find somebody else's explanation that does it better. Do the first few intro chapters, then dip in to some of the other chapters to see how far you get. You want to get a pretty good coverage of the topics in the book, so you know that the topics exist and can increase your exposure to the math involved.
3) If you manage to get through a reasonable chunk of the book from point 2), then you can make a start on the bible: Quantum information and computation by Nielsen and Chuang (https://www.amazon.co.uk/Quantum-Computation-Information-10th-Anniversary/dp/1107002176/ref=pd_lpo_sbs_14_img_1?_encoding=UTF8&psc=1&refRID=S2F1RQKXKN2268JJF3M2). Start from the start, take it slowly, and do all of the exercises.
Nielsen and Chuang is not easy, but it's doable if you utilise some of the techniques I mention in point 2): Google for alternative explanations of concepts that the book explains in a way that confuses you, do all of the exercises, and try to get good coverage throughout the whole book. Make sure you spend time on the early linear algebra and basic quantum chapters, because if you get good at that stuff then the world is your oyster.
Edit:
Just remembered two more excellent resources that really helped me along the way
A) Quantum mechanics and quantum computation, a video lecture course by Umesh Vazirani (YouTube playlist here) is fantastic. Prof. Vazirani is one of the fathers of the field of quantum computing, with a bunch of great results. His lecture course is very clear, and definitely worth devoting serious attention to. Also, he has a wonderful speaking voice that is very pleasant to listen to...
B) Another lecture course called "Quantum Computing for the determined", this time given by Michael Nielsen (YouTube playlist here). In my opinion Nielsen is one of the best scientific communicators alive today (see also his unrelated discourse on neural networks and machine learning, really great stuff), and this series of videos is really great. Communicating this sort of stuff well to non-practitioners is pretty much Nielsen's whole jam (he quit academia to go on and write about science communication ), so it's definitely worth looking at.
As for Quantum Cryptography, in practice it's not really a new kind of cryptography but a way to exchange keys with a physical theorem ensuring that if anybody snoops in you can detect it, throw away your keys and try again. And it needs a quantum medium such an optical fiber cable between the peers (with some limitations). After that it's just regular cryptography.
However, if transferring an extra amount of data at least as long as your message is acceptable, then nothing prevents you from sharing data first from a real random source (quasars, lava lamps...) and using it to xor your message. It turns out that xoring messages with random data only known to the interested peers is unbreakable because every possible message has the same probability of being correct. And since you can detect if anyone saw your key exchange before sending your encrypted data, then you have the advertised unbreakable encryption.
If you want to learn more about the subject I'd recommend you taking a look to this book. While it does talk about algorithmic complexities most of its content just requires good understanding of complex numbers and linear algebra.
And of course, good luck with your future start-up idea. I'm in no way trying to discourage you, just trying to help dispelling the veil of hype so you can get a better picture of what's behind it.
I you are coming from a computer science-y background, I might recommend Quantum Computing for Computer Scientists by Yanofsky and Mannucci, which I've heard good things about.
Another good book whatever your background is Quantum Computing and Quantum Information by Nielsen and Chuang, which is sort of the standard introductory textbook in the field — I've generally found it quite well explained, and it goes all the way from explaining the necessary prerequisites in Linear Algebra and Computer Science, through to explaining various quantum algorithms, quantum error-correcting codes, and some quantum information theory. This is also just a good reference book to have, if you get further into the field.
Also, if you are interested in getting started with programming quantum computers, then it might be worth learning to use a quantum computing language. For example qiskit (IBM's python quantum computing library) has quite a lot of good learning materials such as the qiskit textbook, which teaches the fundamentals quantum computing as well as of the language, or alternatively the lectures from their course Introduction to Quantum Computing and Quantum Hardware, which covers similar topics, and also explains some of the physics of super-conducting quantum computers.
I hope this is helpful — if you have any questions, feel free to ask me here, or pm me :)