Abstract

Quantum computation is slowly becoming mainstream, as research on it is picking up pace, but can it really become part of our everyday life given how much our society depends on classical computation? This paper will discuss what quantum computation is and the effects it can have on the way our society works.

Introduction

Quantum computation is a new domain of computation techniques that has been slowly setting its roots in the world of science over the past few decades. Rather than improve upon what already exists, it is a completely new domain that works on several new principles. Since it will directly affect the societies we live in, it is important to consider just how it would do so.

How will quantum computation bring change to the society we live in?

Before delving into what quantum computation is, and what it is capable of, we must understand what classical computation is and what advancements have come to light since its first instance.

Classical Computation

Classical computation is the computation done through means termed “classical” as they have been used for quite some time. Classical computation is quite limited in physical terms. As classical computation is done using discrete states i.e., which can either be on or off, we cannot do everything with a limited set of states unless we increase the number of states.

If we use finite automata to compute something then we can only do so till our physical limitations allow us to i.e., we cannot have an infinite number of states. The idea of Turing Machines came from this concept, as that gives us an infinite tape on which to carry out the computations. However, it is infinite only in theory as it cannot physically exist. So, in order to make classical computation more powerful and efficient, there have been several enhancements to it that have been modeled in interesting ways. These include the idea of reversibility and probabilistic logic. These ideas were still inherently limited and so came the concept of Quantum Computation.

Quantum Computation

Quantum Computation uses ideas such as superposition to implement computations in faster and more efficient ways. This is possible because it uses qubits rather than bits. Superposition is the idea behind these qubits, it states that a qubit, unlike a classical bit, can have the value 0, 1, or both simultaneously. This makes it react differently than classical states such as giving multiple outputs on the same propositional logic.

Having more than 1 solution makes the computation faster than the classical solution but it also makes it unpractical in most situations. This is the give and take with quantum computation, as such quantum computers are not yet part of the mainstream industry. Significant work has been done on them and it seems plausible that in the next few decades they will start to co-exist with classical computers.

Quantum Computation Basics

In the development of quantum computation, some basic properties have been established. It is important to understand them thoroughly as they are what enables a quantum computer to work the way it does.

Superposition

As discussed above, superposition lets a quantum computer exist in different classical states at the same time. Each state has a different weight (or probability) associated with it. A quantum gate called the H gate is used to convert a qubit into a superposition. It uses the following matrix to carry out the conversion:

Entanglement

The idea behind entanglement is that any two different quantum computers or parts will be connected to each other using methods that are incomprehensible in the domain of classical computation. So, if an entangled object is circular in nature then we would know that the object entangled with it would also be circular in nature.

Interference

Interference lets different superpositions combine and become one just like how waves can be added to each other. If they are positive and negative then they will be subtracted from each other, else if they are both of the same sign they will be added.

Possible Applications of Quantum Computers

Since a lot of work has been done on quantum computers they have been put to use in the form of some applications. These wouldn’t necessarily be in the best working condition yet as research is going on. These applications can also be either a positive implementation of quantum computation or a negative one.

Breaking Cryptography

Cryptography is using computers to create secure communication channels between two computers. It first encrypts information when it is sent out and then decrypts it when it is to be received. Cryptography is based on basic mathematical problems which are easy to compute but not easy to go back to i.e., to compute it in reverse.

Since quantum computing is so powerful and fast, it can break these cryptographic algorithms which are in the classical sense ‘unbreakable’; as even applying a great amount of brute force to them would take longer than the existence of the universe. To put this into perspective brute forcing RSA (one of the most secure public key cryptography algorithms) would take $5.95 \times 10^{211}$ years meanwhile the universe is $13.75 \times 10^{9}$ years old.

Peter Shor, an American mathematics professor devised his efficient Shor’s quantum algorithm to find the prime factors of large numbers in 1994. Since most cryptography algorithms are based on prime factors, this was a groundbreaking discovery as it could calculate the public key of algorithms such as RSA. If RSA is easily broken in this manner, then much of the computer systems we rely on to do basic stuff such as transfer money or receive calls can be easily taken into control by anyone who wants to misuse the power of quantum computation.

There exists a classical field of computation called post-quantum cryptography which is aimed at creating cryptographic algorithms which do not break even with a quantum computer working on breaking them. Similar to this, there exists quantum cryptography which utilizes the power of quantum computation to encrypt and decrypt data.

Search and Optimization

Since quantum computation solves problems fast, it also searches really fast. In many situations, large datasets need to be searched for whatever reason. Quantum computers can do this work in a significantly smaller time when compared with classical search techniques. These search algorithms are optimized using techniques such as simulated annealing and gradient descent in classical search. Alternatives to these also exist in the quantum realm of searching.

This idea extends to machine learning using quantum computers. Machine Learning is already really powerful when done using classical techniques, it has beaten expert players of popular board games. Since these machine learning techniques work on fitting a dataset to its predictive model, it basically optimizes the problem. As discussed above this is something quantum computers would excel at as they would decrease the time required to optimize the said problem.

Even though search and optimization would be made better using quantum computation the data that needs to be read and worked on would still have to exist in a classical state, this is where quantum computers will lack, as constantly changing the state of stored data to between classical and quantum states will be technologically very challenging.

Positives and Negatives of Quantum Computers

As we have gone over some applications of quantum computers, we can see that it is sometimes a good thing and sometimes a bad thing, and that is because of how powerful the form of computation is. Applications such as breaking cryptography is a very dangerous tool if given to the wrong hands.

Apart from the security aspects of it, quantum computation significantly improves the time required to do a lot of regular computations. This is a really good thing given how complicated most of the daily life computer tasks are becoming. Nowadays computers run multiple software simultaneously so it is important that their performance is improved. And if quantum computers become mainstream, then this optimization issue will be fixed.

Limitations of Quantum Computers

The biggest limitation of quantum computers is their unavailability to the public sector. There are very few companies such as IBM and D-Wave which create quantum computers. Even though access to them is relatively available, quantum computation is extremely sophisticated and as of now, it is out of bounds for any hobbyist who wants to get their hands on a real quantum computer.

One needs to be well versed with how quantum computers work in order to access them in the limited time they can get with these services. One hidden limitation is that since quantum computation is new it has a lot of errors in its computation. Errors like these are fixed in classical computers while they run, as a lot of research has gone into that. And the same has to occur with quantum computers if they are to become mainstream.

Conclusion

After careful analysis, it is clear that in the next few decades quantum computers will be abundant to some extent. This would mean that classical computers would slowly become obsolete. But before that happens there would be a time when some people who can commercially afford a quantum computer would have it and it would put others at risk as they could use it for illegal means such as breaking cryptography algorithms.

So, before it happens work needs to be done on fields such as post-quantum cryptography in order to future-proof the idea of quantum computers. As history has told us, development in computers will not stop at all costs so it is crucial that we make quantum computers safe to use for everyone.

Also published here.