Superposition, entanglement, and interference. Join us on this episode as we're learning more about quantum computing and what the future holds for us.

This episode's guest is Sahar Ben Rached. She is a Research Master's candidate in Nanotechnology at the Faculty of Sciences of Tunis. She is currently a Quantum Computing research intern at the IPE, Karlsruhe Institute of Technology in Germany. She is a Qiskit Advocate and the Co-Founder and Local Coordinator of QTunisia, the first community of Quantum Computing enthusiasts in Tunisia, aiming to promote and teach about quantum technologies.

**George:** Hello, everybody. Welcome the Lights On Data show, superposition, interference, entanglement. We're going to talk about quantum computing with our guest, Sahar Rached.

**Diana:** Sahar is a Research Master's candidate in Nanotechnology at the Faculty of Sciences of Tunis. She is currently a Quantum Computing research intern at the IPE, Karlsruhe Institute of Technology in Germany. She is a Qiskit Advocate and the Co-Founder and Local Coordinator of QTunisia, the first community of Quantum Computing enthusiasts in Tunisia, aiming to promote and teach about quantum technologies.

Welcome Sahar. How are you?

**Sahar:** I'm good. Thank you so much for having me. How are you?

**Diana:** Very, very, very good and very excited to have you on. Let's start with the more personal question if that's okay to warm us up. Tell us a little bit about your hobbies or what you do in your free time.

**Sahar:** I actually picked up so many hobbies throughout the years. I don't have one specific hobby that I always go to when I have, my spare time. But it's kind of like going into phases, you know, when I get interested to learn about something. So I dedicate my time and energy to learn about it. And then I just go to the next one.

At some point I was very interested in to sports. I was going to the gym so much, and I would start to participate in as many events as possible. Other times I would be just interested in writing and reading about a specific subject. And for example, right now I'm interested in arts, even though this is very new to me. And it turned out to be a very exciting year, especially learning about the history of arts and its evolution. Especially that I'm now in Germany.

So I'm trying to get many opportunities to go to museums and art galleries. There are so many here in Germany, so it's a very interesting topic and I'm very interested to learn more about. Yeah, I don't have like one specific hobby. I just am very interested in so many things.

**Diana:** So just before we started, you mentioned that your brother and sister, they followed your parents. And you're the only one in the family who studies physics. So how did that happen?

**Sahar:** Actually, my interest in physics started at a very young age. It was mostly with astronomy and my parents encouraged me with that.

They would buy me the books that I wanted and I would watch so many documentaries and they would just support me on that. And my interest in physics just kind of guided me throughout all my academic choices after that. It was mostly in high school and after that at university.

And a couple of years ago, it was in 2019, I left my startup, which I co-founded, in order to get back to school and actually the field that I'm really interested to have a career in, which is physics. So I started my masters in physics and specializing in another technology and metaphysics at the university of Tunis El Manar.

And at that time, the news came up about Google achieving the quantum advantage. That was actually the first time that I would hear about quantum computing as a field that was arising and achieving results already. Two months after that, I was in contact with my professor asking him about something and he suggested that I would go to cascade camp in Johannesburg in December, 2019 and participate in the first quantum computing hackathon running.

So I got up, you said, yes, it was doing iBM quantum. So why not? Why would I say no? And at that time I was a completely beginner. I just knew the ABC's of quantum computing from a few online courses that I took and few tutorials on YouTube. And I just went to the camp. And even though I did not do much on that hackathon because I was the complete beginner, it opened my eyes to that field of the quantum computing and the growing community of IBM and of course, other universities in South Africa. I got really interested into the field, especially with the presentations and how they were really excited about the future coming up with this technology. Right after I got back to Tunisia, I took the time to learn on my own.

Trying to find any resources that I would get on the internet, to learn more of quantum physics and quantum computing, especially that my master's was actually aligned with the theme because as nanotechnology it's mainly quantum physics and we had the module on quantum information science.

So, it was kind of like all aligning into the field. After a few events that I organized in Tunisia and after a few courses that I got, I even taught for my university a few classes for quantum programming. I tried to network with as many people as I can from Africa, from around the world by attending the online events that were running throughout the year.

And I would also started QTunisia in September, 2020, which was affiliated to Qworld. So, we had so many events going on and workshops to try to raise awareness about the field and try to get people excited as much as we were about quantum computing and quantum technologies in general.

So, yeah, it's been going for quite some time now. I'm really enjoying it.

**George:** That's quite the journey.

**Diana:** Yeah, I know. And just as Ravit says a very interesting background, very interesting background indeed.

**George:** So, Sahar, can you explain us in simple terms, if possible, what is quantum computing?

**Sahar:** Let's start by defining what is a quantum computer. So, a quantum computer is a computational machine which we are using to do calculations, especially complex calculations that we cannot do efficiently using a conventional computer.

What is special about the quantum computer is that it uses the fundamental phenomena of quantum mechanics, which are mostly include superposition, entanglement and interference. And this is the core strength of this machine.

Superposition, let’s define what a superposition is. We say that the conventional computer is based on logic bits. So, logic bits would be either zero or one at a time. However, a quantum bit or a qubit can be in a superposition of zero and one, meaning that it can have state that is a combination of zero and one. And this gives us the opportunity and the possibility to have infinite number of values that we can give to the qubit.

This means that we have large computational space where we can run complex calculations using qubits and we can have more efficient computational methods and we can encode large data in a more efficient way. This is mostly to say that superposition, which is main feature of a qubit, can give us the potential to have more values that we can use to encode our information or our input.

For entanglement, which is also a second phenomena that is strange, but still we can use it to run computational exercises or problems, which is to make the values of qubits dependent of each other. This means that instead of having, let's say two qubits, which are separate and working separately (we don't have like a correlation between the two calculations running on the two qubits) ;using entanglement, we can make the two values dependent of each other so that when we do the measurement on one qubit, the other one would automatically fall into deterministic value. The sort of coordination or correlation between the qubit can be very beneficial to run certain quantum algorithms and to say the least, most of the quantum algorithms and protocols are based on entanglement. And we can see that this feature is actually very beneficial.

Now, interference. This is mostly to increase the probability of having the right answer and decrease the probability of, having the wrong answer. One of the applications for interference that we can see clearly is in Grover's search algorithm. This is one of the basic algorithms in quantum computing. For Grover search algorithm, it's mostly the protocol that we use in order to extract data efficiently from a very large database.

**George:** That's mind blowing. And is there any chance of getting the wrong data as a result or getting it dirty in the process?

**Sahar:** Yeah. For now, the machines are not perfect. There is so much noise, that makes the probability to have wrong answer quite high. So that is one of the main limitations of the hardware that we have available right now. However, in the long run, when the technology is mature enough, then we can trust that the machine would give us the right answers or the right outcomes based on its of course, its analysis and it's processing of information that we have given.

So, for now it's best to stick to the results that you can predict theoretically, and also test on your quantum machine. As long as your predicted results or theoretical results are close to the results given by the machine, then you are going into the right direction.

However, this is only limited to how the hardware is now available, but within five to ten years, that's when we expect the technology to be more mature and, the hardware will be of high fidelity. Then we can just rely on the given results by the quantum computer.

**George:** So what's the state right now of the quantum computers? Is it prevalent? Or is it more, at the university level? I know Google has it. Amazon is investing into it. Apparently, China, just created a quantum computer. Right? It was just the news a couple of days ago that apparently, it's a million times quicker or more powerful than the Google’s. I don't know how true that is, but, I guess there's a lot of interest in it.

**Sahar:** It is. Yes. And you have mentioned actually big companies and big nations investing in this technology. So, we have, as you have mentioned, Google, there are also IBM. There's also Honeywell and so many other startups coming up every couple of months that would invest either in the hardware development or the software development of quantum computers. But also, we have, even, national roadmaps to invest and to support in this technology. Such as France, US, China, also Australia and Canada, all the big nations also have trusted this technology would be very beneficial to boost technology development in their countries.

So currently, what is the state of quantum computation technology? It’s that we are still in the development stage. I would call it also the pre-market stage. What does that mean? Well, we have technology that works to a limit. To a limit because we still have a few engineering challenges that make all the technologies under investigation still not mature enough to have commercial use or to just produce the commercial value.

But we know that the science backs up his technology, we know that theoretically speaking, these machines would work. And theoretically speaking, we have the algorithms that actually prove that there is a quantum advantage to solving certain problems. Of course, not all problems or situations would need a quantum computer, but in certain cases where we need a more efficient way of solving the problems, that would mean less time and less energy and less money.

Quantum computers can be very advantageous in those special cases. So, something else is that so many companies are just investing in the technology to the point that we have already so many products available. For example, we have application modules already available, publicly available and for free, we have so many programming languages coming up from the big companies, but also from start-ups. We have real computers available even for free. So, anyone now can just create an account and have access to up to 15 qubits for free. And this is actually a very huge advantage in order to raise awareness about the technology, but also to draw the attention, to the technology from developers, from scientists and researchers. And to eventually boost the technology and accelerate its development.

I would say that at the beginning, in this pre-market stage, we have a prototype. This machine that is actually working. The science is backing up this technology, but still we would need that application that would make it available into the market and, would make it one of the technologies that can be beneficial to big companies, but also to societies.

That does not exclude that for some quantum machines already, the applications are used even on the commercial side. For example, quantum annealers, which are in a stage that is much more developed than the university quantum computers.

Quantum annealers are the machines that are mostly used for optimization problems. I would like to mention D-Wave Systems, which is the leader on the market for quantum annealers and already its technology is showing an advantage in finance, for example. For financial problems it has proven already that, using quantum annealers than to conventional classical, optimization methods, there is quite an interesting outcome.

And there are even companies and banks that are using these results in order to enhance their technologies and their uses. So, yes, we estimate that within five to ten years we would reach that maturity stage where the technology is available to the public, and it can be used for commercial products.

And until then, then there is so much to do. Also, we have so many engineering, challenges to overcome. Also, the research that has to be done on algorithms and creating a commercial value out of this very, very, interesting technology.

**George:** So, is the main benefit of quantum computing, the speed at which you can calculate things or are there other benefits as well?

**Sahar:** Quantum computers were initially envisioned as machines that would work with the same laws of nature. This was the vision for quantum computers in the early 1980s.

Because at that time you were very interested to know how really the quantum world works. We wanted to understand more of how nature works and understand more of the molecular interactions and environments. So that was the initial goal of creating the quantum machine. The interesting thing is that today we have reached this goal.

We have algorithms and we have machines that are able to simulate how nature works. This would be mostly beneficial to, for example, enhance the procedures for drug discovery, for quantum chemistry and for creating new materials. Why is that? Because we have a better understanding of how nature works so we can simulate its environment and we can, of course, do more of engineering works in order to make a product in the end.

To answer your question, yes, the speed up is a very interesting, advantage of quantum computers. When we talk about speed up we're actually talking about the efficiency of calculation methods using quantum computers. Let me mention the milestone of Google in 2019, which is reaching the quantum advantage.

What do we mean by the quantum advantage? It's mostly when we solve a problem using a quantum computer that would have been impossible to solve using a conventional computer, of course, within a reasonable time. So just within the abstract for this milestone, which can be found in a paper that is published in Nature, Google has solved a problem within 200 seconds that would have taken a conventional computer 10,000 years to solve.

**Diana:** Oh my goodness.

**Sahar:** Yes. So that's what we call the speed up. It looks like it's really huge. When we talk about, for example, the factorization of large numbers, when we talk about the simulation of a large molecule of 2000 or more atoms, when we talk about searching certain information in very, very large data sets or databases, then yes, the advantage of speed-up is a very beneficial feature of quantum computers.

Now, the example given from Google is not really, an application, it was mostly a proof of concept with a chip of 53 qubits. Today we have more than 53 qubits and some companies are aiming for 1 million qubit within one quantum chip. So, imagine how with just the increase of number of qubits, we have even a lot of computational space.

In the end, we have really efficient ways of solving problems which theoretically would take thousands of years. And just to reduce that to a few seconds using quantum computers, then yes, I would say that so many research labs with so many companies are actually looking for such a ways of using this technology.

As you can imagine, many fields would be affected by quantum computation. Let's say on the top of the list would be encryption. So that would be cybersecurity because one of the ways that we can use quantum computers in is the factorization of large numbers or large prime numbers, which would threaten a few security protocols that are available today.

So, the first thing is to use these machines to rather have better security. Also for molecule simulation, also for finance and optimization. As you can see we already have a few fields that will mostly benefit from quantum computing in the short to long term.

**George:** By the way, great plug because October is the month of, cybersecurity. And we all know how important that is. I want to take a couple of questions from the audience if that's okay with you. And the first one comes from Jose, and he's wondering how much noise in the outputs will be reduced by more mature hardware, I guess in five to ten years from now. Is there an estimate of that?

**Sahar:** Already we have some error correcting algorithms that would reduce significantly the noise in the hardware right now. It will never reach 100% because the noise would always be there, but it will always be “how we can reduce that noise to the point that it does not affect the right answer or the right outcome given by the computer”. I cannot estimate what is the best outcome or the best percentage that we can reach in the efficiency of the quantum hardware. But right now, we can even create qubits or quantum gates that have fidelity of 98% or 99%. Imagine that within 10 years, when we have best technologies, when we have better control of our machines, then it can be very close 100%, but it will never be 100%.

**George:** And Kingsley was wondering, where did the variables that are used for interference come from, internally or externally?

**Sahar:** For the interference, when I talk about the interference, it's mostly because when we modeled the qubits, as quantum states, then we can model more of them using the wave functions. It's basically wave functions where we have encoded our input. And it's mostly the interaction between them that would give us the final result.

I would say it's internal because the qubit is itself modeled as a wave function. In the end, the outcome will be given by the states of qubits.

**George:** Thank you. Like Ravit is mentioning “so much to learn from Sahar”. So, Sahar, if somebody wants to get started with this, you mentioned there are a few resources out there. Can you mention some of them?

**Sahar:** Of course. Today there are so many available resources, even for free. I know there are very expensive courses, but you really don't have to take those. If you prefer tutorials, then I would recommend the Kurzgesagt channel on YouTube. It would be very good resource to start with. There are even algorithms and basis of quantum computation and the basis of cascade. And there are even more advanced lectures. They have a series for researchers who are interested in more advanced concepts of quantum computing. And of course there are the protocols and algorithms that you would need to understand what quantum computation is.

Other than that, there are, books. I would recommend, “Quantum computing and programming with Python” by Robert Loretto. “Dancing with Qubits” by Robert S. Sutor. There are also researchers from IBM quantum, but this is not only exclusive to IBM quantum is just that I know these resources already. And, if you would like also the textbook from Kiska, it's also very good start.

If you would like to go for a more advanced concepts or even lectures that are quite lengthy, but also very interesting, which I used mostly for learning, there are the quantum information science lecture notes from MIT OpenCourseWare.

I've used this to study quantum information and to get an in depth understanding of how quantum circuits and quantum algorithms work. This was actually one of my choices, but, I like better to study with notes and lectures than to just, follow a certain, tutorial. They are very helpful, but to each one they have their own.

I would say those are the most interesting things to start with. And of course then if you integrate more communities, if you network with more people, especially from the field, then you would always have recommendations and you would always have events where there are presentations of the latest results.

Then I would recommend attending those events, especially they are now online and for free. So let's take advantage of that as much as we can. And yes, for me, these have been my sources to learn quantum computing so far.

**George:** Thank you. And of course, we want to encourage people to follow you on LinkedIn.

**Diana:** I wanted to say if you want to ask Sahar, if you weren't able to write things down or to remember them, make sure that you connect with Sahar on LinkedIn.

**George:** And Sahar, you also mentioned that one could create an account? You get free 15 qubits, where, where could one get this from?

**Sahar:** Yes. so it's actually the IBM quantum experience. This is what it's called, so you can create an account. And, yeah, if you have like basic programming knowledge, then you can start with this. There are so many, tutors on that, but yes for now, we have access up to 15 qubits and up to 20 systems. So, you can use 1 qubit, 5 qubits, 15 qubits, however you want. Plus, the simulators.

The simulators are the classical way of doing quantum computation. It's as if quantum computers were perfect. There are simulators of up to 5,000, qubits available. I assume that with the increasing number of qubits on the quantum chips of IBM quantum, there would be even more free access to more qubits. We will just have to wait and see how many qubits we can get within the next few months.

**George:** That's great. Thank you so much Sahar. Now we're coming to an end here and I know there's a few more questions that we didn't get a chance to get to, but please feel free to reach out to, to Sahar ben Rashed on LinkedIn and follow her there.

**Diana:** Can I ask you just one last question? We have two more minutes so Sahar if you can answer this very fast, what are the next steps?

**Sahar:** For my next steps, it's really hard to decide on this right now. I will have a clearer path by the beginning of 2022. I'm considering my options to either start in the industry of quantum computing, because I also have a background in working in business development.

I also want to use my skills in quantum computing and also business development for my career. And later on, I would continue with the PhD because I understand that having a PhD in the field is a very, very good plus, or I would just directly start with a PhD, stay in in academia for a few more years and then get into the industry.

In all cases I would like to be more involved with in the industry than academia, within quantum computing, because I'm interested to see what we can do with this technology to have better products and just better standards for technology and society in general.

**George:** Yeah. Yeah.

**Diana:** All are good choices, whatever you choose. It's going to be amazing.

**George:** Yeah, I guess with, with quantum, it'd be nice to be in different places at the same time,

**Sahar:** Superposition states.

**Diana:** Which is more possible today that everything is online. All right, well, thank you very much Sahar. This was a very, very interesting, good luck with everything. Everyone please follow and connect with Sahar on LinkedIn.

Thank you very much for joining and for your very, very good questions. We'll see you next week.

**George:** Thank you.

**Sahar:** Thank you! Bye, bye.