We’ve Got Quantum Problems

Quantum computing is both a major threat and a panacea for the long-term future of public blockchains.

As people, it can be easy to see the world in binary. The light is on or the light is off. You succeeded or you failed. You like cats or you like dogs.

It should therefore be no surprise that our initial design of computer systems reflects this fairly simplistic take on the world. Each bit is a 1 or each bit is a 0. Now, this isn’t a dig on the power of classical computers. There are several reasons why binary patterns are incredibly powerful. They are easy to understand, easy to program, and most importantly, they are incredibly reliable. Errors can be traced back systematically to certain points along the system and when fixed, are certain to not happen again. The implications of this are massive. Our world is increasingly reliant on this logic and everything from payment processing to landing airplanes is built with these binary technological assumptions in mind.

However, what if this wasn’t the only way a computer could operate? It isn’t.

Let us start by reminding ourselves what the purpose of a computer is. Ultimately, computers are just data processors. They can prep data for storage (often in the form of 1s and 0s), they can extract stored data, they can alter data and they can perform operations on data. Now, through experimentation, we have found great ways to perform all of these functions in modern computers. Billions of tiny capacitors are charged and drained of electrons systematically by your laptop as your computer reads and writes data to perform various tasks. How do we get the computer to do this better? Well, maybe we can add a second computer or a third, or a computer with more capacity. In the blockchain, we link together hundreds or thousands of computers, all coordinating various actions across the chain, acting as one single unit.

This binary technology is impressive and always improving, but it has one great limitation. It is too logical.

Let’s start with a maze. This is a simple maze with only one path that can effectively take you from the start to the end. In addition to the one correct path, there are two incorrect paths. These incorrect paths lead to a dead end. Asking a standard computer to solve this is easy. The computer will test the first path. If the path results in a dead end the computer will try the second path. If the second path is the correct path it will stop and return it as a result. Simple.

Now, let’s take that maze but make it massive. Massive as in truly huge, the size of an entire stadium with billions or trillions of possible paths all of which lead to dead ends except for one. The binary computer tries the first path. No luck. Then it tries the second path. Still no luck. The computer will keep guessing path after path after path, intent on finding the proper route. This problem is no longer an easy solve. Instead, it could take days, weeks, or even years for your laptop. Maybe a supercomputer could solve it faster but as the size of the maze grows, the computational challenge does too.

Enter quantum computing.

 
Quantum computers are not bound by this binary thinking. Instead, they exist at a unique intersection of computer science and quantum physics, harnessing the unique properties of atomic states as they become very small and very cold. In quantum mechanics, particles do not need to exist in a single state at all. Instead, they can exist simultaneously in multiple states. For example, a photon does not need to have a positive charge or a negative charge. It can have both while it is in a state called superposition.

 
Quantum computing uses this property to replace bits with qubits, enabling extremely efficient computer properties. Because the subatomic state of the computer can exist in a realm of probabilities instead of hard 1s or 0s, the computer has no need to run through each path of the maze path by path. Instead, the computer can view the entire maze at once and near-instantaneously assess the proper route. A problem that might take a classical computer 10 years could take a quantum computer 10 minutes or less.

 
For cryptography, this is a major issue. Many of the algorithms that are built to ensure security across blockchains are constructed purely on the premise that deconstructing them would be too computationally expensive or challenging. In a world of quantum computers, this assumption could break. Bad agents could run a number of attacks on public ledgers including intercepting transactions to redirect them into their accounts and building infinitely long bad chains to steal funds. The underlying security features that currently make the blockchain as secure as it is would be compromised.

 
Now, it is important to note these issues would not be specific to blockchain technology. All kinds of internet protocols and security features would be compromised in this world. Computing as we know it would have to change. Now, some estimates say we are still a decade away from these issues becoming a reality. Current quantum computers are still unable to entangle as many subatomic particles as would be needed to run these kinds of calculations. Still, the threat looms.

 
Fortunately, the solution lies in the problem. Take the internet and the blockchain quantum. One of the most significant challenges facing cryptography today is the ability to create true randomness. In a world of binary instructions, telling a computer to create a real random number is an impossible task. Somewhere along the line, the computer had to process an instruction to create some string of bits. In a quantum world, this instruction could be decrypted and vulnerable. However, by nature of quantum computing’s probabilistic tendencies, blockchain technology could finally have a key to creating real randomness. According to many leading cryptographers, the challenge will not be creating post-quantum secure blockchain technology but actually enacting these updates under decentralized governance systems. Of course, the creation of private blockchains could ultimately fix this problem at the private enterprise level.

 
In practice, blockchain technology still represents one of the most secure methods of storing and governing data available today. While quantum computing represents a revolutionary change to computing power and a potential threat, it will also enable the enhancement of protocols to a level that is beyond what we currently think possible. In these ways, the long-term combination of quantum thinking and blockchain will serve to improve the use cases of this technology in the world.