A few days ago, IBM made several significant announcements about their research efforts and marketing plans for quantum computing for the next few years. These announcements may mean that IBM has now achieved a level of quantum hardware sophistication that exhibits a quantum supremacy over classical computers, meaning quantum hardware of a sufficient level that can perform calculations that cannot even be attempted on classical computers in practical terms.
For details see:
The IBM Quantum State of the Union (Nov 16, 2021)
https://www.youtube.com/watch?v=-qBrLqvESNM
Here is a briefer synopsis:
This Insane Quantum Computer is IBM's Last Chance
https://www.youtube.com/watch?v=Cix4O4X9In4
For more on quantum supremacy, see this Wikipedia article:
Quantum Supremacy
https://en.wikipedia.org/wiki/Quantum_supremacy
So it appears that quantum computing might finally be with us in just a few short years. In Quantum Software, Quantum Computing and the Foundations of Quantum Mechanics, The Foundations of Quantum Computing and Quantum Computing and the Many-Worlds Interpretation of Quantum Mechanics, I alluded to why quantum mechanics might be of interest to IT professionals because I figured that someday they might have to work with quantum computers. I took my very first course in quantum mechanics at the University of Illinois at Urbana in 1971, and I learned from that experience that working with quantum computers would not be easy unless a good deal of abstraction was used to hide the details of quantum mechanics. That is because quantum systems are very difficult to understand philosophically. As my first professor in quantum mechanics told us, "Nobody really understands quantum mechanics, you just get used to it.". Then in the fall of 1972, I took the Modern Physics Lab course at the University of Illinois. It was a five-hour course with no examinations. My grade depended solely on my lab reports for the assigned experiments and 50% was for a semester-long independent lab experiment on the Mössbauer effect. One of the assigned experiments dealt with the nuclear magnetic resonance of protons in water which required us to manipulate the quantum spin of protons. I found the experiment to be very difficult but I finally was able to make the spins of the protons to resonate with a great deal of difficulty. So I was quite surprised when the first MRI scan was performed on a human being in 1977. MRI stands for NMRI or Nuclear Magnetic Resonance Imaging. The "Nuclear" was later dropped because it was learned that patients fear all things that have to do with "nuclear" technology. I just could not believe that the fussy quantum nuclear magnetic resonance of protons could be put to a practical use! That is why I never wrote off the possibility of quantum computers coming to be.
My IT Job is Already Impossible - Do I Really Need to Learn About Quantum Computers Too?
Most likely, you will never have to learn the confusing details of quantum mechanics because you will only be making calls to Cloud-based quantum microservices. For more on that see:
Don’t employ quantum computing experts? Just head to the cloud
https://www.protocol.com/manuals/quantum-computing/quantum-computers-cloud-aws-azure
The reason that most IT professionals will not need to learn about how quantum computers work will be the same reason that most IT professionals know nothing about CPU instruction sets or how to write a compiler for them. All of that will likely be abstracted away for you. The main thing you will need to know is that quantum computers will be able to do certain things for you much faster and some things that are actually impossible on classical computers. The reason why is that quantum computers take advantage of two things that have been bothering physicists ever since they invented quantum mechanics in 1926.
1. Superposition - A quantum bit, known as a qubit, can be both a 1 and a 0 at the same time. A classical bit can only be a 1 or a 0 at any given time.
2. Entanglement - If two qubits are entangled, reading one qubit over here can immediately let you know what a qubit over there is without even reading it.
Figure 1 – Superposition means that a qubit really does not know if it is a 1 or a 0 until it is measured. The qubit exists in a superposition of states meaning that it is both a 1 and a 0 at the same time.
Superposition is important because a classical computer with 127 bits of memory can be in only one of:
2127 = 1.701 x 1038 = 170,100,000,000,000,000,000,000,000,000,000,000,000 states.
But a quantum computer with 127 qubits of memory like the just-announced IBM Eagle processor can be in 170,100,000,000,000,000,000,000,000,000,000,000,000 different states all at the same time!
Entanglement is important because when two qubits are entangled, they can instantly affect each other no matter how far apart they are.
Figure 2 – When qubits are entangled, neither one knows if it is a 1 or a 0. But if you measure one qubit and find that it is a 1, the other qubit will immediately become a 0 no matter how far apart they are.
Superposition and Entanglement have both been experimentally verified many times even if they do not make much sense. In
Quantum Computing and the Foundations of Quantum Mechanics and Quantum Computing and the Many-Worlds Interpretation of Quantum Mechanics, I covered two popular explanations for these phenomena known as the Copenhagen Interpretation and the Many-Worlds Interpretation of quantum mechanics. I also covered the Transactional Interpretation which behaves a bit like TCP/IP. The Copenhagen Interpretation maintains that when a quantum system is observed, it collapses into a single state so that a qubit that is in a superposition of being a 1 and a 0 at the same time collapses into a either a 1 or a 0. Entangled qubits collapse in pairs. The Many-Worlds Interpretation maintains that a qubit in a superposition of being a 1 and a 0 at the same time is actually two qubits in two different universes. You are a being composed of quantum particles and when you measure the qubit, you are not really measuring the qubit, you actually are measuring in which universe your quantum particles are entangled with the qubit. In one universe you will find a 1 and in the other you will find a 0. The same thing happens when you measure entangled qubits. In one universe the qubits are 1 and 0 and in the other universe they are 0 and 1. The Many-Worlds Interpretation may sound pretty nutty, but it actually is a much simpler explanation and does not need anything beyond the Schrödinger equation that defines all of quantum mechanics. Plus, as David Deutsch has commented, if a quantum computer can perform the calculations of a million computers all at the same time, where exactly are all of those calculations being performed if not in Many-Worlds? For more on that see Quantum Computing and the Foundations of Quantum Mechanics.
So How Does a Quantum Computer Work?
The details are quite complex using quantum algorithms that use quantum gates for logical operations, but you should be able to get an intuitive feel just based on the ideas of Superposition and Entanglement. Remember, a quantum computer with 127 qubits of memory can be in 170,100,000,000,000,000,000,000,000,000,000,000,000 different states all at the same time and many of those qubits can be entangled together into networks of entangled qubits. This allows people to essentially write quantum algorithms that can process all possible logical paths of a given problem all at the same time!
Figure 3 – Imagine a large network of entangled qubits processing all possible logical paths at the same time producing massive parallel processing.
Bensen Hsu has some really great YouTube videos on quantum computers:
What is a quantum computer? Superposition? Entanglement? Simply explain with a coin!
https://www.youtube.com/watch?v=KRECGZxzP9k&list=PLpZnenmughqWZFQZ6igZW3Y264U9mrggm&index=1
Superconducting qubit, the tuning fork of a quantum computer
https://www.youtube.com/watch?v=qmeE8OCVtaY&list=PLpZnenmughqWZFQZ6igZW3Y264U9mrggm&index=2&t=1s
Trapped-ion qubit, the maglev train of a quantum computer
https://www.youtube.com/watch?v=YrNrR92ql9s&list=PLpZnenmughqWZFQZ6igZW3Y264U9mrggm&index=3
How to build a quantum computer?
https://www.youtube.com/watch?v=zzGfSgEabUw&list=PLpZnenmughqWZFQZ6igZW3Y264U9mrggm&index=4
Bensen Hsu also has some great YouTube videos on possible quantum computer applications:
Tired of stereotyped new iPhones? Let quantum computer help!
https://www.youtube.com/watch?v=rOCl8XfsdJ8&list=PLpZnenmughqXm0LZdIgAjAoxM7KBdQzFL&index=3
The NEW era for AI! How could Quantum Computing change Artificial Intelligence?
https://www.youtube.com/watch?v=HkIQBia3zDs&list=PLpZnenmughqXm0LZdIgAjAoxM7KBdQzFL&index=2
A new way to predict future prices? Why are financial giants rushing into quantum computing?
https://www.youtube.com/watch?v=L_I1fRCfrLg&list=PLpZnenmughqXm0LZdIgAjAoxM7KBdQzFL&index=1
Quantum Computers 40 Years Later
It has now been 40 years since Richard Feynman first proposed using quantum computers to simulate physical systems. This is another example of the value in doing original research that does not pay off until many decades later. Below are a few of the original papers that got it all started.
Simulating Physics with Computers (1981)
Quantum Mechanical Computers (1985)
by Richard Feynman
http://physics.whu.edu.cn/dfiles/wenjian/1_00_QIC_Feynman.pdf
Quantum theory, the Church–Turing principle and the universal quantum computer (1985)
by David Deutsch
https://royalsocietypublishing.org/doi/abs/10.1098/rspa.1985.0070
Comments are welcome at scj333@sbcglobal.net
To see all posts on softwarephysics in reverse order go to:
https://softwarephysics.blogspot.com/
Regards,
Steve Johnston
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