since Jun 18, 2003

Biography

Ph.D. in Math; M.S. in Computer Science; Professor of Computer Science and Mathematics at Drew University in Madison, NJ; Author of Java For Dummies, Java Programming for Android Developers for Dummies, and other books.

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Madison, New Jersey, USA

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"Superposition of different possibilities" is a nice way of thinking about it. Imagine a calculation that's so large that it would take classical computers millennia to solve. In a quantum computer, all the possibilities could be represented at once by being superposed over one another. You can have one qubit whose possibilities are both 0 and 1 at the same time. So, ten qubits represent 2^10 = 1024 possibilities at the same time. With only ten qubits, you can be calculating on over 1000 possibilities. Imagine what you can do with 10,000 qubits!

The difficult part of quantum computing algorithms is getting the quantum computer to sift out the correct possibility among all 1000 of them or of all 2^10000 of them. That's where you encounter very cleverly conceived quantum computing algorithms. A quantum computing algorithm takes 2^10000 calculations and, somehow, filters out all the incorrect ones.

Unfortunately, quantum computing algorithms aren't easy to understand without lots of background or lots of help. That's why I wrote the book. (Well, actually, I wrote the book because I'm fascinated by the subject, but that's another story.)

The difficult part of quantum computing algorithms is getting the quantum computer to sift out the correct possibility among all 1000 of them or of all 2^10000 of them. That's where you encounter very cleverly conceived quantum computing algorithms. A quantum computing algorithm takes 2^10000 calculations and, somehow, filters out all the incorrect ones.

Unfortunately, quantum computing algorithms aren't easy to understand without lots of background or lots of help. That's why I wrote the book. (Well, actually, I wrote the book because I'm fascinated by the subject, but that's another story.)

5 months ago

Laptops won't support quantum key distribution. But two quantum computers (one at ABC company and the other at XYZ company) can agree on a private key and then relay the private key to their companies' classical computers.

There's also post-quantum cryptography -- schemes being developed and tested that are resistant to eavesdropping by agents with quantum computers.

There's also post-quantum cryptography -- schemes being developed and tested that are resistant to eavesdropping by agents with quantum computers.

5 months ago

Babies books or not, there are ways to understand complicated physics concepts (perhaps on a very shallow level) that don't involve a lot of technical background. I can explain some ideas about superposition and entanglement without doing any math. True, the listener will get the wrong ideas about some aspects of superposition and entanglement (many aspects, maybe) but they'll also get some general idea of what's going on and it might encourage them to learn more.

5 months ago

Hi Don,

A quantum simulator will work to simulate a small number of qubits. The one I commonly use simulates a quantum computer with 32 qubits. But 32 qubits is "nothing" compared to the number of qubits you need in order for a quantum computer to have advantages over classical computation. One estimate says that it takes a quantum computer with 10000 qubits to factor two large prime numbers and crack RSA encryption. Engineers and physicists believe that we'll have quantum computers with large numbers of qubits in a few years. But simulators can never run with large numbers of qubits. That's because the amount of information you can wield with a true quantum computer grows exponentially with the number of qubits. The amount of info in a simulator doesn't grow exponentially.

So simulators are good for doing proof-of-concept, but they won't be able to solve practical problems with quantum computing techniques. A practical program that a large quantum computer will be able to solve in minutes or seconds would take billions and billions of years to run on a simulator.

(Footnote: The Java Strange library is good stuff even though it runs only on a simulator for now.)

A quantum simulator will work to simulate a small number of qubits. The one I commonly use simulates a quantum computer with 32 qubits. But 32 qubits is "nothing" compared to the number of qubits you need in order for a quantum computer to have advantages over classical computation. One estimate says that it takes a quantum computer with 10000 qubits to factor two large prime numbers and crack RSA encryption. Engineers and physicists believe that we'll have quantum computers with large numbers of qubits in a few years. But simulators can never run with large numbers of qubits. That's because the amount of information you can wield with a true quantum computer grows exponentially with the number of qubits. The amount of info in a simulator doesn't grow exponentially.

So simulators are good for doing proof-of-concept, but they won't be able to solve practical problems with quantum computing techniques. A practical program that a large quantum computer will be able to solve in minutes or seconds would take billions and billions of years to run on a simulator.

(Footnote: The Java Strange library is good stuff even though it runs only on a simulator for now.)

5 months ago

I've never read one of the "For Babies" books. I imagine that they have some value for some audience.

5 months ago

Hi Vijitha,

I don't know enough about LLMs to answer that question. Does anyone else on this forum have any thoughts?

I don't know enough about LLMs to answer that question. Does anyone else on this forum have any thoughts?

5 months ago

Hi Marcello,

The D-Wave company is already selling quantum computers that do quantum annealing. Quantum machine learning also looks very promising, but I don't know of any commercial applications yet.

What I've learned from reading about quantum computing is that the development of new technologies isn't "all or nothing." I have two boxes that communicate with one another using quantum key distribution (QKD), but they were sold in 2004, and they seem to need Windows XP to run. Does that mean QKD was commercially available in 2004? Not really. British Telecom says it's rolling out QKD for commercial use in Europe, but I'm sure that it's being used mostly experimentally by British Telecom's customers.

There's definitely a theoretical advantage to quantum computing. But the percentage of practical uses over theoretical research is still very, very small. When people ask me how long it will take before we see real practical advantages, I always reply, "ten years." Honestly, the real reason why I say, "ten years" is because ten is a round number. No one knows for sure.

The D-Wave company is already selling quantum computers that do quantum annealing. Quantum machine learning also looks very promising, but I don't know of any commercial applications yet.

What I've learned from reading about quantum computing is that the development of new technologies isn't "all or nothing." I have two boxes that communicate with one another using quantum key distribution (QKD), but they were sold in 2004, and they seem to need Windows XP to run. Does that mean QKD was commercially available in 2004? Not really. British Telecom says it's rolling out QKD for commercial use in Europe, but I'm sure that it's being used mostly experimentally by British Telecom's customers.

There's definitely a theoretical advantage to quantum computing. But the percentage of practical uses over theoretical research is still very, very small. When people ask me how long it will take before we see real practical advantages, I always reply, "ten years." Honestly, the real reason why I say, "ten years" is because ten is a round number. No one knows for sure.

5 months ago

Hi Don,

Any encryption scheme that relies on factoring large numbers is vulnerable. Schemes that don't rely on factoring large numbers may be vulnerable. (Shor's factoring algorithm doesn't apply to schemes that don't rely on factoring. But other quantum algorithms may apply.) To approach this problem. the NIST agency in the United States has chosen four encryption schemes that are candidates for being resistant to quantum computing. It remains to be seen which of these four are resistant enough to be made into real standards.

Any encryption scheme that relies on factoring large numbers is vulnerable. Schemes that don't rely on factoring large numbers may be vulnerable. (Shor's factoring algorithm doesn't apply to schemes that don't rely on factoring. But other quantum algorithms may apply.) To approach this problem. the NIST agency in the United States has chosen four encryption schemes that are candidates for being resistant to quantum computing. It remains to be seen which of these four are resistant enough to be made into real standards.

5 months ago

Hi Celso,

Quantum computing is great for some problems and awful for some other problems. You'd never want to use quantum computing to do word processing, even if you could find a convoluted way to do it. So, no, quantum computing isn't destined to replace classical computing. In addition, when you use a quantum computer, you have to feed it instructions using a classical computer. So, in a sense, all quantum computing is really hybrid computing.

Quantum computing is great for some problems and awful for some other problems. You'd never want to use quantum computing to do word processing, even if you could find a convoluted way to do it. So, no, quantum computing isn't destined to replace classical computing. In addition, when you use a quantum computer, you have to feed it instructions using a classical computer. So, in a sense, all quantum computing is really hybrid computing.

5 months ago

Johan's Java library is a simulator. You write Java code to describe a quantum circuit, and the library goes through the motions of figuring out what that circuit would do. I've been encouraging Johan to write a compiler that translates the Java code into machine instructions that a quantum computer can execute.

5 months ago

There's a book called "Quantum Physics for Babies." Your 12-year-old isn't a baby, but the existence of such books is a good sign.

5 months ago

Hi Don,

Quantum computing is good at some problems and very bad for other problems, but there's no way to quickly summarize the good set and the bad set. The Traveling Sales problem is a good one, but it's nothing like the factoring problem. For the factoring problem to be useful, it has to yield an exact solution. (You can't decrypt an encrypted message with an approximate solution to the factoring problem. It has to be exact.)

However, the way quantum computing works, the meaning of the phrase "exact solution" isn't the same as what you might expect. If you factor 15 using quantum computing, you might get a result that's something like this:

With probability 93%, the factors are 3 and 5.

With probability 7%, the factors are 4 and 5.

For a quantum algorithm to be effective, you have to run it many times and look for a result whose probability is higher than all the others.

So is that an exact solution? In a way, it is. But probability is also involved.

Quantum computing is good at some problems and very bad for other problems, but there's no way to quickly summarize the good set and the bad set. The Traveling Sales problem is a good one, but it's nothing like the factoring problem. For the factoring problem to be useful, it has to yield an exact solution. (You can't decrypt an encrypted message with an approximate solution to the factoring problem. It has to be exact.)

However, the way quantum computing works, the meaning of the phrase "exact solution" isn't the same as what you might expect. If you factor 15 using quantum computing, you might get a result that's something like this:

With probability 93%, the factors are 3 and 5.

With probability 7%, the factors are 4 and 5.

For a quantum algorithm to be effective, you have to run it many times and look for a result whose probability is higher than all the others.

So is that an exact solution? In a way, it is. But probability is also involved.

5 months ago