How and Why Quantum Computing Can Change Astrophysics Forever
Outer space is a big place.
When studying the endless expanse of the universe, limits in our technology and understanding are always being broken. In fact, astrophysical pursuit has been the pioneer for many new innovations, from GPS to memory foam.
The edges of our power are once again being pushed by the complexities of space. Thankfully, there is an emerging technology that could very well be the key to unlocking much more of the universe than we could imagine.
Enter, quantum computing.
Quantum computing is a brilliant new innovation that shows incredible potential for improving existing research systems and being used to build new ones. The powerful computational power of quantum computers could help us explore the hostile environments of black holes, accurately map out and analyse dark matter, collect more accurate data from further back in time and space, and so much more.
Brief Overview of QC:
Before we get too ahead of ourselves, we should address the elephant in the room.
What exactly is quantum computing, and what makes it so promising?
According to IBM, the leading company in quantum computing, “Quantum computing is a rapidly emerging technology that harnesses the laws of quantum mechanics to solve problems too complex for classical computers”. The way that it does this is through qubits.
Qubits are to quantum computers what bits are to classical computers. However, instead of presenting data in stages of either 1 or 0, qubits represent that data in 1s, 0s, and everything in between. The process of having a particle represent multiple states of information at the same time is called superposition, and only occurs on the quantum level. Once the superpositioned quantum particle is measured, however, it snaps to a binary result and is taken out of the superposition state.
Think of a coin. When lain at rest, the coin is either heads or tails (1 or 0). But, if you spin the coin on its side, then it is impossible to say that it is either heads or tails at any moment. While spinning, its value is every possibility in between and including. Only when you stop and observe the coin, does it show a reading of heads or tails.
Superposition is also the phenomenon described in the famous Schrodinger’s Cat thought experiment.
Is the cat dead or alive? Until the box is opened, one may assume it is both, at the same time.
Due to this superposition, any number of qubits can run exponentially more calculations than the same value of classical bits. A mere 300 qubits can produce more states of information than there are particles in the observable universe.
This sort of power is what makes astrophysicists very excited about this new technology. Being able to compute and analyse so much information in such short amounts of time makes quantum computers true frontiers.
They can be used to:
- simulate complex natural environments — black holes and neutron stars
- render out linear and quadratic solutions — orbital paths
- create and digitally test new materials and compounds — improved impact and heat-resistant materials for space travel
Physically, qubits are charged-up electrons that are held in place by being contained in silicon and other conductive metals. This allows scientists to directly communicate with singular qubits by sending them microwaves and detecting the waves sent back. This works very well due to the sensitivity of qubits, however, it’s also their weakness.
The Problem:
Whilst quantum computing is limitless in terms of potential, in practice, we are currently limited by the sensitivity of the qubits. This issue is referred to as quantum decoherence.
Qubit decoherence refers to any time when external forces or particles, such as sound waves, gamma rays, x-rays, photons, etc. Such interference can prematurely switch a qubit's state, taking it out of superposition and disabling it from making calculations. They also limit the amount of time which a qubit can retain the information it has in a quantum state, which even regularly is currently only a few seconds.
Such unwanted interference also adds to the problem of scalability. When one qubit is interfered with through external forces, the data from other qubits is inhibited. The more qubits you have, the more likely it is for a single error to majorly disrupt information.
Qubit decoherence is the ultimate hurdle to get over in quantum computing since error-correcting will make the computers fully reliable for their aforementioned incredible uses.
Research and Solutions:
In terms of overcoming this large problem, there’s good news and bad news.
Bad news: There is no current working solution. Quantum computers are stored in near absolute-zero vacuums, but interference still makes its way through the metal chamber walls.
Good news: Companies and research teams are very heavily invested in tackling quantum decoherence in a variety of ways. The most integral of these is a process called quantum error correction. Error correction in general is not that difficult of a task; it’s essentially programs that are run to fix any mistakes in application and processing that can come about in computational hardware. In classical computing, error correction is implemented in the case of bits accidentally flipping from 1 to 0, or vice versa.
In quantum computing, the problems are much trickier than that, and so are the solutions.
Many major technology companies and institutions are currently in the process of coming up with ways to get us to error-corrected quantum computers that are capable of being scaled up. There are currently multiple ways this is being looked after, through the software of error-correcting codes, and the hardware of logical gates.
Quantum error-correcting codes (QECs) are as they sound, codes that are put into qubits to improve their capability to store and process information more accurately over a longer period.
Logical qubits (LQs) are essentially regular qubits but with built-in QEC code. This code is spliced in between layers of physical, compact qubits. They are most sought after to replace qubits with silicon encasing. Some of the companies developing these logical qubits are the front-runners in the QC race — Google and IBM. Logical qubits work with scalability as it has been shown that a LQ made of 49 qubits was able to beat out one made of 17. However, the hardware is the easy part.
Both Google and IBM are working on their own quantum error-correcting code that can be implemented in logical qubits. The implications of what logical qubits can help with in terms of quantum decoherence and scalability are huge. QEC codes work by silently correcting errors in qubits without further interfering with their quantum information or changing their underlying state.
There are still some issues with QEC and their implementation through logical qubits. QEC codes are being worked on for their aspect of scalability, as it currently seems that the most effective way to use them on a small number of qubits, won’t work in more complex systems.
Even further with QECs and LQs, companies such as Xanadu, a Canada-based QC research company, are developing photonic qubits. These are qubit chips that work by having micro-lasers shoot individual photons through tubes where they are erased of outside noise and put into quantum superposition states to present information. The advantages of using these photonic chips are immense.
They:
- Work at room temperature
- Are easy to scale up
- Simple to manufacture
- Have built-in error-codes
There are also other solutions being worked on by smaller-scale research teams, such as nuclear computing, direct coding, and abstract qubits. These massive strides in error correction and decoherence are not only presenting solutions to the current QC problems but also bringing forth innovation of new ways of advancing this emerging technology.
Conclusion:
Quantum computing is an emerging technology that seems almost like magic. A new brand of machine harnessing the powers of quantum mechanics to propel information processing and simulation. With so many applications, it makes sense why companies, research teams, and government agencies alike are competing to fix its issues and bring it to its fullest potential.
Issues with decoherence and scalability have been barricading us from further progress since the time of QC's conception, but with every passing day, we get closer to overcoming those obstacles.
With the work of researchers in error-correcting, logical qubits, photonic qubits, and other non-contemporary routes, there is no doubt a boom of quantum computational advancement in the near future.
Even as someone who is more invested in physics than the computer science of quantum computing, I am very excited to see how QC will be utilized in the future. Progress is being made fast, and I sit excited to see where this technology will take us — both in existing fields, and applications we couldn’t even dream of.
