Understanding The Wonders of Quantum Computing As A Layman
“NOT ONLY IS THE UNIVERSE STRANGER THAN WE THINK, IT IS STRANGER THAN WE CAN THINK!” ~ Werner Heisenberg
(The reader-friendly blog has been framed into independent chunks as far as possible, so that she/he may revisit later, if needed, and conveniently take away any required concept.)
Quantum- If you’re here reading this blog then I’m sure you must have been hearing this word and its derivatives- Quantum Cryptography, Quantum Internet, Quantum Electrodynamics and so on for quite a while now- especially since Google declared Quantum Supremacy on building its 54-qubit processor Sycamore; and since the Quantum war amongst the mega players Google, IBM, D-Wave, Rigetti etc began.
Well Quantum Computing has been under development for decades, yet catching the attention of young researchers and budding start-ups happened majorly after IBM open-sourced its 5-qubit Quantum Computer via IBM cloud in 2016.
A Glance at Origins
Quantum Physics has baffled the human brain innumerable times for more than a century. The curiosity-driven mind has always instigated an urge in itself for exploration and understanding of Natural Phenomena. With the advent of theoretical Physicists conducting thought experiments and changing the course of the subject altogether from classical to modern, an obvious need to experimentally justify the theories arose. Physicists began to feel the necessity of conducting extremely complex calculations; designing heavy experimental equipment like the LHC for extraordinary precision; and simulating natural and physical paradigms with ‘near-zero error’ accuracy in finite time, sustainably. Hence, the need for greater computational power had been in tremendous demand in multiple scenarios. Furthermore, it was the unexplained mysteries of nature, pondering upon which some of the elite scientists of the 20th century- Paul Benioff, Richard Feynman and Yuri Manin gradually understood the powerful implications that a computer based on Quantum Mechanics could have! That’s where Physicists and Engineers came together to join hands and began creating Quantum Computers! Later when the idea popularised, not just Physicists, but intellectuals in almost every field- Chemistry, pharmaceuticals, biology, finance, internet, artificial intelligence, cyber security and numerous more began to explore the marvels of Quantum Computing that could possibly have applications in their work in near future. And further what would you expect?
Education! Universities such as MIT, University of Waterloo etc and well-renowned online educational websites like EDx, Coursera etc began providing courses in QC and derived (concept/application-based) subjects.
Visualising the Sphere of Quantum Computing
Now that you’ve come this far, I guess you’d like to know a little about the technicalities. Let’s dive into the building blocks of this sphere then! (Assuming that there will be readers who have little or no knowledge of the subject, I’ll try to be as basic as I can.)
1. Quantum Superposition-
Got it? Cool.
No? Let’s try understanding another way :)
If you have a coin around, toss it once. Like always, you’re gonna wait till it gets down, right? Well in our case, just observe it while it’s flipping in the air. Is it heads or tails?
You’d say that doesn’t make sense, isn’t it? Until it gets down, it’s both heads and tails. Well that’s what quantum superposition is. Being in multiple states at the same time in different proportions! Nature works that way.
Another little example-
Forget gravity, buoyancy, air resistance or any force you can think of at the moment. Ideal scenario.
Now imagine a single pendulum oscillating between two vertically opposite points A and B. Its identity is defined by its position. Unless it is stopped at either of the two points (‘observed’ in terms of Physics), at variable instants of time it can be defined by both- 30%A and 70%B; 50–50; 75–25; 86.1–13.9; infinite combinations! That’s what ‘different proportions’ as I referred to in the previous example be understood as.
Analogous to ‘bits’ in classical computing, Quantum Computing is based on ‘Qubits’ — quantum bits. Why am I talking about qubits suddenly? Clearly, they’re bits following the principle of quantum superposition- 0 and 1 at the same time! Hence, in terms of computation, 1 qubit is equivalent to 2 classical bits; 2 to 4; 3 to 8 and so on. So, if you compare your PC to a QC, just raise ‘2’ to the power of ‘number of bits’ you’ve got!
Further, unlike classical computing, we do not have capacitors here. Therefore, the bits aren’t defined as 1 or 0 by mere presence or absence of charge. Qubits are basically electrons or nuclei with oscillating spins (quantum states).
To visualise the functionality, just replace the pendulum in Figure 2 with a constantly deflecting needle of a magnetic compass. Replace A and B with 1 and 0 respectively.
You may have studied about transistors based on metal oxide semiconductors (MOSFETs) which form the basis of multiple electronic devices today, including the one you’re using to read this blog. Remember Moore’s Law which suggested that the number of transistors in a dense IC doubles every two years? Growing at that rate, we’ve reached the scale of single digit nanometer-sized transistors! But does research ever stop? Not until nature is explored to zenith, and well that day is yet too far. It’s time to update Moore’s Law and welcome Neven’s; let’s grow at the scale of “doubly exponential” as we reach the Angstrom level.
Let’s enter the Quantum Realm!
2. Quantum Entanglement-
Wait. Do you like pizza? Imagine a friend comes over and orders two pizzas online, one for each of you. Your choices are different but both are equally hungry. Few minutes later, the pizza boxes are delivered, but they’re unlabelled. How do you know which one is yours? They look identical! Clearly, you’ll have to open either one and check. Now, here’s the catch. It might seem of negligible importance in this scenario, but astounds if curiously thought upon! The moment you recognise the pizza in the box you open first, you become sure about the other (provided the valet or restaurant didn’t make a mistake :p).
This information transfer took absolutely no time! And that’s how, in simple terms, Quantum Entanglement can be understood.
Two particles in space separated by any imaginable or unimaginable distance are said to be entangled when the properties of either of them cannot be described independently; you know the closed box contains Signature Double Cheese as soon as you find your Supreme Exotica in the opened one!
Also, when two particles are entangled, the change in state of one affects that of the other. Ever watched twin kids? If one cries, there’s a high probability that the other one will either cry or laugh after watching her, even from a distance.
Let’s get a bit more technical now.
When talking about Quantum Entanglement, it’s not possible to avoid the EPR Paradox. It formed the controversial basis of the subject where Albert Einstein referred to entanglement as “Spooky action at a distance”. However, measurement of properties like- momentum, spin, polarization, position etc for many particle pairs- photons, neutrinos, electrons and in some cases large molecules, even when a pair was considerably separated apart, yielded satisfactory results justifying the idea of quantum entanglement.
Taking into account, all factors- information transfer, distant measurement, inverse wave function collapse (can happen when a property is “measured” and disturbs the entire entangled particle pair system) etc, the advantages of Quantum Entanglement are considered true, but with the strong-held notion that the Theory of Relativity is not defied by it- no information or logic transfer occurs at a speed greater than that of light.
One important application of Quantum Entanglement, as you probably may have guessed by now, is Quantum Internet!
3. Quantum Tunneling-
Do you like magic? Ever read/watched any fictional story wherein a person simply walks across a wall? You might have.
These magic tricks aren’t necessarily illusions. They’re realistic possibilities built on the brilliance of Quantum Tunneling!
In technical terms- when a subatomic-particle traverses across a potential barrier (let’s say an electron (as a wave) tries to move across a concrete wall), such that its probability disappears at the starting point and appears at a point across the barrier, without appearing anywhere at all inside the barrier during its journey- it is said to have undergone Quantum Tunneling. In other terms, a particle with energy levels less than that of a barrier, is able to cross it.
This teleportation-like phenomenon is currently limited to subatomic particles only. Yet, let’s see what the future beholds.
Remember the discussion about transistors? Electronics engineers, be ready for a mental hassle (more than you already have :p). If the size of classical transistors is reduced further, the electrons will be able to tunnel across, disturbing all current flow directions and V-I calculations!
The phenomenon isn’t available in classical Physics. Quantum Computers thus have an edge over classical ones, i.e., there exist certain problems which only the former can solve.
Applications of Quantum Computing
Having discussed the basics, let’s have a look at some applications and the current trends in Quantum Computing across the globe.
1. Quantum Machine Learning-
Last two decades have seen an exponential rise in the interest levels of engineers and entrepreneurs for Artificial Intelligence, majorly since movies like The Matrix! A desire that indwells in every human who loves exploration cannot refrain from pushing himself towards building better computational designs and algorithms to delve deeper into the mysteries of nature and the Universe. Artificial Intelligence, as the term clearly portrays, is the ‘smart’ behaviour of machines when they act like, or in a way try to imitate human beings in mental aspects and decision making processes. Machine Learning is simply the way to create and enhance that intelligence, analogous to human learning for human intellect. Research based on theoretical methods followed by heuristics (Deep Learning) has been on a rise since decades. From Naive Bayes to Neural Nets, the machine learning arena, as a whole, has experienced exponential growth- be it in terms of data acquisition, development of algorithms or computational power.
There has been a tremendous rise in interest levels of students and industrial R&D to explore and implement quantum-engineered solutions to enhance computation.
There are two aspects- benefitting of AI from Quantum Computing and vice-versa.
- Talking of the former, Quantum Computers have an ability to perform superfast Linear Algebra- which forms the basis for Machine Learning algorithms. These quantum accelerated calculations are performed on a state space that grows exponentially with qubits! This is the 1st generation of Quantum Machine Learning(QML). Supervised and Unsupervised Learning applications like principle component analysis, k-means clustering and recommendation systems are encompassed within this first generation. These algorithms perform exponentially faster on quantum data. To perform computations on classical data, it needs to be embedded into quantum states first. The 2nd generation of QML has also emerged with the availability of Noisy Intermediate-Scale Quantum (NISQ) processors, and is based on heuristic methods. Their empirical study is possible with the heavy computational capability of Quantum Hardware. Just like Deep Learning was a development in the Machine Learning arena, this second generation is analogous to it in the field of Quantum Machine Learning. Are you expecting Quantum Neural Networks here? If yes, well you’re right. QNNs form the basis of models’ development, training strategies and inference schemes in QML. Google’s TensorFlow Quantum White Paper is the most wonderful resource I’ve found on the internet to work in QML. The aforementioned information is based on its reference.
- Quantum Computers originally came into development in order to explore and simulate the marvels of Nature/Physics, remember? They’re now going to enhance AI as well. When prodigies in QC and AI coalesced, the idea of simulating Natural paradigms emerged. Simulation of certain phenomena like intermolecular bonding, ionic interactions, radioactive decay, nuclear reactions, satellite communication and numerous more like Combinatorial Optimization which would’ve taken years if done using classical computers, can be done within hours, rather minutes with Quantum Computing hardware using Quantum Machine Learning Algorithms.
2. Post Quantum Cryptography
Current cryptographic techniques, based on algorithms like RSA are responsible for providing security in today’s Cyberspace.
Networking, information transfer, real-time communication, online financial transactions etc are protected by them.
Encryption techniques are based on two aspects- keys and encryption algorithms. Imagine a number which is a product of two prime numbers. Let’s say- 35. Here, the encryption algorithm is simple multiplication and the keys are the prime factors of the number — 5 and 7 in this case. This process forms the basis of RSA algorithm. Pretty easy right? But here was just a two digit number for understanding purpose. What if there’s a 7-digit number with just two prime factors? Would you still be able to produce the answer that quick? In real world cyber-security, RSA uses numbers of a magnitude that large (2048 bits), that present classical computers cannot break it within a normal human’s lifetime! Hence, our RSA encrypted data is pretty safe from security breaching by hackers.
But, what if Quantum Computers try to break it? Though current ones aren’t yet capable of doing so, we may have superior ones (better algorithms, hardware and greater number of qubits) within three decades, as per the growing trends (for eg- this paper on breaking RSA encryption in 8 hours), which could be.
This is henceforth a threat to the prevailing security systems from Quantum Computers.
And to tackle it, Post Quantum Cryptography(PQC) comes into picture. Now encryptions based on PQC will be unbreakable by even Quantum Computers!
PQC is based on information carrying polarized photons’ transfer. It yields millions of possibilities for the eavesdropper, hence making it near-impossible to break.
Understanding PQC in detail is itself an entirely different story. So, maybe sometime later?
Major Highlights of The Pre-Quantum(Current) Era
Emergence of Start-ups- Realising the immense capability of Quantum Computing, numerous entrepreneurs have come forward and built start-ups based on its technicalities in multiple arenas- Storage, Security, Cloud, Research etc. An exhaustive list can be found here.
- Market Size- https://thequantumdaily.com/2020/04/15/mckinsey-forecasts-quantum-computing-market-could-reach-1-trillion-by-2035/
Development of Open-Source Research Tools and Communities-
- https://github.com/rigetti/pyquil — Python library for quantum programming using Quil. (By Rigetti Computing)
- https://www.tensorflow.org/quantum — TensorFlow Quantum (TFQ) is a quantum machine learning library for rapid prototyping of hybrid quantum-classical ML models. (By Google)
- https://qiskit.org/ — Qiskit is an open-source quantum computing software development framework for leveraging today’s quantum processors in research, education, and business. (By IBM)
- https://qiskit.slack.com/#/ — Qiskit Community Slack Channel
Major Algorithms in Quantum Computing:
Well, this is it! I hope I was able to provide a good learning experience. Feel free to communicate!
See ya :)
