# Quantum Future

The quantum vision of reality is strange and mesmerizing at the same time, as Michio Kaku once said : “Common sense has no place in Quantum Mechanics”.

Knowing it is a new and uncommon place, one can expect the quantum innovations to overcome anything we have seen before. We will see that the theory behind it enables some unseen capacities, but there exists some hurdles that slow down its unleashing to the real world.

By using the concepts of entanglement and superposition on quantum bits, a quantum computer can solve some problems faster than a classical computer would. For example, Quantum computers are pretty useful to solve NP-hard problems such as the Boolean satisfiability problem, known as the SAT problem. Using the Grover’s algorithm, the complexity of the evaluation of a boolean proposition of \$n\$ variables goes down from \$O(n2^{n})\$ to \$O(n2^{n/2})\$ by applying its quantum version.

A even more interesting more problem to solve is the Bernstein–Vazirani problem where given a function \$f\$ such as \$f(x)=x.s=x_{1}s_{1} + x_{2}s_{2} + x_{3}s_{3} + … x_{n}s_{n}\$, one has to find \$s\$. While the classical solution requires \$n\$ queries to find the solution, the quantum version requires only one query !

Photo by Jason Leung on Unsplash

Quantum computing proves very valuable for security issues. One interesting riddle it answers is the following : How can two communicating parties share a key to encrypt and decrypt their messages without any third party stealing it ?

A valid answer would be using Quantum Key Distribution, which is a method of communication that implements cryptographic protocols which involve quantum mechanics. This method rely on the following quantum principle : The measurement of a system generally disturbs it. Knowing that a third party would measure the quantum state thus disturbing them, the two communicating parties can therefore know if a communication is secure by establishing a threshold for eavesdropping.This method is used for securing bank transfers in China and for transferring ballot results in Switzerland.

However, there are some serious hurdles to the progress of quantum computing in order to match the requirements of an industrial scale use and deployment. First, quantum computers operate at temperatures near absolute zero since any heat in the system can introduce errors. Second, there exists a scalability issue for quantum chipsets. Knowing that there exists chips of the order of a thousand qubits, expanding to millions or billions of qubits for fully fault-tolerant, error-corrected algorithms will require significant work.

If one would like to tackle real life problems using quantum solutions, the best way to do it is to use a hybridization of classic and quantum algorithms using quantum hardware. This way, the part of the problem which can be solved faster using a quantum algorithm can be transferred to a quantum computer for processing. One example would be using a Quantum Support Vector machine for solving a classification problem, where the matrix exponentiation task is handled by the quantum computer.

There exists an initiative for contributing to the development of open source tools for quantum computing called Quantum Open Source Foundation. Its goal is to expand the role of open source software in quantum computing, focusing on the one using current or near-term quantum computing technologies. The foundation also offers links to open courses, papers, videos, development tools and blogs about quantum computing.

An interesting project it supports concerns quantum cryptography and is called OQS-OpenSSH. It aims to construct a public key cryptosystem that is believed to be safe even against quantum computing. Since it is still under development stage, it is recommended to make use of hybrid-cryptography using both quantum-safe public key and classic public key algorithms.

You can even some fun learning about quantum computing by playing Entaglion, a two players game made by IBM Research. The goal is to rebuild a quantum computer from scratch. The game is really instructive and could be a great way to introduce the youth to the quantum world.

All in all, the mysteries of the quantum world hasn’t stopped amazing us, and will surely continue on in the future. The exciting part is yet to come !