Quantum physics is definitely interesting, with all its quirks and contradictions, but its usefulness is limited. One of the biggest applications of this science in quantum computing, the next generation of problem solving machine. In this month’s blog post, I discuss what these new computers are, the basics of how they work, and current efforts in their development.
What Is A Quantum Computer?
A quantum computer is a machine that makes use of quantum properties to perform calculations faster than traditional computers.
How Does It Work?
Qubits have 3 states: 1, 0, and 1/0 simultaneously. This simultaneous property allows the qubit to run all the permutations at the same time, instead of one by one like a classical computer. This allows it to cut down time needed for problems involving checking many different possibilities, such as solving mazes. A quantum computer can check all possibilities at the same time and thus solve the problem faster.
While there is uncertainty in the qubit system, we can still use the information by making use of entanglement. When particles or qubits are entangled, changing the state of one automatically influences the other. In this way, even if it is uncertain to the outside observer, it can still relay useful information within the computer using entanglement to perform useful calculations. This entanglement between the different qubits means that the more connections between qubits, the more powerful the computer becomes. This allows quantum computers to become more powerful at an exponential rate as more qubits are added, as supposed to the linear rate of traditional computers.
How Does It Compare?
Sure quantum computers have the potential to perform way more calculations than the traditional computer by making use of superposition, but where would this actually be useful?
As mentioned when explaining the basic mechanics, quantum computers are able to check a different possibilities faster than traditional computers by checking multiple at the same time. One of the major applications of this property is in data security and encryption. Current encryption technology makes use of the RSA algorithm, which encodes numbers by manipulating prime numbers. It is very secure because it is hard for traditional computers to break large numbers down into the original primes. However, with quantum computers, checking possibilities becomes a lot easier.
Because quantum computers threaten our most common form of cyber security, efforts have been made to beef up encryptions, and find a quantum computer proof method. IBM has already developed a system making use of lattice problems that will supposedly thwart quantum computers. The basic premise is to add certain numbers in a public set together, and that to break the encryption, you would need to determine which numbers were added together.
Current Developments:
Scientists still have lots of hurdles to overcome before they can harness the full potential of these systems. However, they have made a lot of progress in the last few years.
Quantum Supremacy
One of the biggest original goals of quantum computer development was something called quantum supremacy, which was the time when a quantum computer could compute something the best supercomputers can’t compute. In 2019, Google announced that it had hit this milestone with Sycamore, a 53 qubit quantum computer. Sycamore used loops of wire that could have a combination of currents of 2 different energy levels. This allows each wire to become a qubit. Google used this computer to run a certain calculation that it estimated would take 10,000 years for 100,000 traditional computers, in only around 3 and a half minutes.
The calculation itself is actually very straightforward. It requires computers to describe a certain random state of many quibits. The reason a quantum computer can perform so much better than a traditional one, is that each pair of qubits can hold 4 bits worth of info. This means the 53 quibit calculation would take 2^53 regular bits to compute.
Recently (on July 15th, 2021), Physicists in China have used their 66 qubit quantum computer to confirm the results from Sycamore in 2019. In this calculation, they only used 56 qubits to make the test more similar to the 53 qubits that Google had.
Google has also made progress on Sycamore. On July 14th, Google published a paper talking about an experiment they did with their quantum computer. The results showed that using more qubits to preserve a piece of information or data dramatically decreases the error. This gives hope for future quantum computers, where they have enough qubits to not have to worry about random error or interference.
Quantum Companies
A few days ago, on July 14, Quantum Computing Inc was put on Nasdaq. This company seems to allow clients to use a quantum computing system called Qatalyst to solve logistical and computational problems. While this isn’t the most state of the art application of quantum computing technology, it is interesting to see this new technology begin to branch out and actually find real world applications.
You can read more about this company here: https://www.zdnet.com/article/quantum-computing-inc-to-list-on-nasdaq-expand-qatalyst-visibility/
Desktop Sized Quantum Computers?
Not exactly.
On July 2nd, Cambridge came out with a project to develop a operating system for quantum computers, called “Deltaflow.OS”. Think of it like Windows or IOS, but for the generation of computers. Its job is to allow scientists to manage the computing power of qubits a lot easier.
The end goal for this system is to allow the same quantum software to be run on many different quantum computing systems, allowing computers to be scaled down and commercialized. While it is only a single chip now, the potential of this idea may power the next technological revolution.
Important vocab:
- Qubit: A unit of info or data that can be a 1, 0, or 1/0 simultaneously; usually a subatomic particle that forms the basic building blocks of the quantum computer.
- Decoherence: The main issue with quantum computing is the delicacy of the machine. Qubits want very specific conditions, otherwise they may lose the uncertainty that makes them so powerful. This phenomenon of losing uncertainty is called decoherence.
- RSA Algorithm: One of the most common encryption methods that manipulates prime numbers to allow only the sender and reciever to decode the info. You can read more about the RSA algorithm here: https://www.abc.net.au/news/science/2018-01-20/how-prime-numbers-rsa-encryption-works/9338876
- Lattice Problems: A new way to encrypt data that makes use of a process quantum computing is not good at cracking. You can read more about this here: https://www.scientificamerican.com/article/new-encryption-system-protects-data-from-quantum-computers/
You too can experience quantum computing!
While we can’t really use a real quantum computer right now, we can still experience the magic. IBM has developed a game called Hello Quantum that simulates properties of quantum computers in video game form. Read up about this here: https://www.ibm.com/blogs/research/2018/07/hello-quantum/
Extra Resources And References:
While Quantum computing is progressing by leaps and bounds, there is still a lot to be done. Most current quantum computers still have high amounts of error, or need to have specific environments and temperatures to prevent decoherence. However, there is no doubting that the quantum revolution is just on the horizon. We will just have to wait a few years before we can get our hands on a qubit powered system of our own.