Tell me, Professor, where did your fascination with quantum physics come from?

Maybe I’ll start with physics in general. My fascination comes from the family home. I was surrounded by physics in childhood, my dad is a physicist, his brother is a physicist. My cousin taught me physics at school. It was a wonderful time anyway because apart from teaching me physics we also often went on trips out of town. Dad was fascinated with physics, you could see that. He would get emotional about his various achievements or failures. He would often work late into the night. Editing wasn’t easy in those days and there was a lot of effort involved. So physics was alive at home. From the start Dad would give us various books to read. I remember one of them, a lexicon of Nobel prize winners. There were photos in it so at the beginning I would just look at the photos and read the captions underneath. Dad could say a few words about each of those people, so there was the fascination with these figures. Dad would also tell us excitedly about the birth of quantum mechanics because it all happened suddenly. Starting with the work of Planck, some time had to pass, with Einstein and Bohr, and then there was the bang. The bang which to a certain degree was down to young people. This incredible pace of creating the theory which is so different from what we see is amazing. I had contact with it from very early age, with this mind-boggling, not only scientific but also socio-historical, phenomenon. Dad would always demonstrate various phenomena to us, saying that it was all physics and we were amazed. One such ‘cult’ object was the radio. It is amazing that physicists created the radio. Dad would read us sketches by Władysław Natanson about Maxwell and tell us that the radio is there, in his equations. Hence my interest in physics in general. And of course quantum mechanics, as the strangest thing in physics, something which transcends our vision of the world and which forces us to cast aside the conventional way of thinking and for which perhaps there is still no good philosophy.  I don’t think natural philosophy has somehow absorbed the lesson in quantum mechanics yet and has not yet reconciled itself with it completely. So such were the roots of my interests. I did not even entertain the idea that you could not be a scientist. There was such an atmosphere at home that for me as a child it was obvious that I would be studying physics and become a scientist. It is amazing that it was not just some naïve childish thinking, it really did happen this way. 

It’s a very difficult discipline. Richard Feynman said: “If you think you understand quantum mechanics then you don't understand quantum mechanics".

It’s true. What we generally understand in quantum mechanics is how to calculate something. But this is not an understanding. In my everyday work, as I calculate various effects and try to predict them, I always have in front of my eyes the most difficult thing in quantum mechanics i.e. the inability of establish a division between the observer and the world observed. It’s a really strange phenomenon and it would seem that it might negate the existence of science altogether, because science requires the observer not to be part of the object observed. The observer must be able to single phenomena out, to isolate and describe them. And what is miraculous here is that the description does seem to be possible. Yes, quantum mechanics is for me, simply, a miracle. And it is precisely for this reason that it cannot be fully understood, because there’s something very unique taking place between the observer and the object observed. However, you can calculate and predict things, and you have to have a kind of quantum common sense. You do hone this sense with time and even without fundamentally understanding quantum mechanics, you can somehow still find your way around these things for the benefit of science and for the benefit of a more and more precise description of nature.

Is this still physics, professor? Maybe mathematics or in fact philosophy already?

Indeed, quantum mechanics is an area where the descriptive tools have become so detached from what we are describing that they constitute some separate world of mathematical equations. We lack a direct connection between the numbers we work out on paper or a computer and some observable effects around us. The path from mathematical formalism to the world of nature is long and far from obvious. So here, something really interesting indeed has taken place, with mathematics becoming much more autonomous when it came to observing nature than it was in previous theories. Another strange trait of quantum mechanics is precisely this link to philosophy. Because the subject is not clearly separate from the object, certain philosophical paradoxes arise. So by dabbling in quantum mechanics, we find ourselves in the midst of abstract mathematics and at the same time we come up against philosophical issues. I need to add that within my field of study, quantum mechanics is even more distinct from what we would call physics, because I deal with quantum information. This is an attempt to employ the laws of quantum mechanics to information processing. To a large extent, we take only mathematical formalism from physics. When we are able to move efficiently within the formalism, then we don’t really have to remember any terms in physics.  It is a little like dealing with informatics where you simply have bits which are being processed. An IT technician doesn’t need to know that a bit means two different voltage levels, for him a bit is a zero or a one. It’s very similar with us because the formalism which we employ is connected with Hilbert space and our informatics is very mathematical. It is not exclusively combinatorial mathematics, there are many different branches at play. So in quantum information you really can deal with physics in such a way that you have hardly any contact with physics whatsoever. Of course, the majority of scientists who work in quantum information rack their brains over how to translate all these various results into something concrete. That is, how to build some device, and then of course is when the vast expanse of physics starts because you have to implement all this mathematics into specific physical systems, whether they be photons, ions or solid bodies etc. I have had a few papers recently which featured the Hamiltonian i.e. a mathematical object which is somehow closer to physics and I am happy that I could touch on physics even a little.

Professor, it is easy to obtain funds for research if the practical application lies in the future. My question is: is this ever going to be translated into an everyday experience?

The answer here is, on the one hand, easy because quantum information is vastly promising. Amongst other things it promises two things in one. On the one hand a quantum computer which, if it could be constructed, would be able to quickly perform prime factorisation of natural numbers and thus break the currently popular type of coding, which would be hard to call a promise, it is more of a threat. On the other hand, quantum information promises a kind of antidote should our coding systems ‘collapse’ because of a quantum computer. This antidote is quantum cryptography i.e. an option of sending information in a situation when the security is not protected by the principles of traditional cryptography which say that there are no computers in the world that are too strong or algorithms too fast. Quantum cryptography promises security which is to some extent based on Heisenberg's uncertainty principle, therefore this  security is more fundamental and provides an interesting alternative to current coding methods. However, from what we are able to observe on the market, the quantum coding devices which are being produced haven’t made much of an impression on the market. The armies of various countries may be interested in the issue and, as far as I know, every so often a person from our branch disappears i.e. starts working for the army. At the moment our branch is already offering an alternative to traditional cryptography. Great effort is also made to build a quantum computer and here I am really unable to say whether this will work or not. Recently we have also been conducting work on another application which may be easier to accomplish i.e. generating random numbers. At present random numbers are produced with the help of pseudo-random algorithms which generate deterministic strings which look random. Random numbers may also be acquired from the environment, but the environment may be monitored, so generally if we want to produce random numbers without referring to the laws of quantum mechanics, then we have a problem because all theories, apart from quantum mechanics, are deterministic. Because of this we may generally find everything out and it may at times turn out that our random numbers have been planted by a third party. Therefore pure randomness does not exist, randomness only refers to a subjective lack of knowledge. And it is only quantum mechanics which introduces randomness which is not a lack of knowledge, it is fundamental. For this reason, there is a stream of research in quantum information where improvements are being made to a random number generator, based on quantum mechanics. There are quantum random number generators on offer which, I am sorry to say, are said to be mainly used by online lotteries which I would rather didn’t exist at all. However, randomness is useful not only in casinos but also for cryptographic purposes. It is something to possess random numbers which no one else knows. Those quantum devices  which generate random numbers do have one fault, though, in that you have to trust the producer that a given device has been built according to the specifications. Of course a physicist who deals with quantum optics may dismantle such a device and find out for himself. But the average buyer can’t do this. For about ten years now research has been conducted to make sure that the device works in a way which would make it possible to test it  without looking inside, just by the results of measurements, which in fact can be done by everyone. Scientists have devised a way not so much to generate randomness but to boost it. However, the protocol proposed required a great number of devices which additionally had to grow with the number of random bits which we wanted to produce. Our group has managed to come up with the first protocol in which this number of devices is constant and small i.e. 12.

Professor, you have also graduated in Theology. Does a knowledge of physics bring one closer to God?

It would be best at this point to quote a fragment of a beautiful poem by Adam Asnyk which goes like this: 

With every secret now revealed to you, 
The soul of man expands within the new. 
And God still bigger grows! 
(transl. Jarek Zawadzki)

For me dealing with physics is exploring the work of the Creator. The more complicated the work is, the more you admire the Creator. Someone said that little knowledge drives you away from God and great deal of knowledge brings you closer. By exploring nature we come up against such mysteries as the black hole or elementary particles, it is an incredible world. With the development of science, the structures we get as gifts from nature make one respect He who created it all more and more.

And finally, Professor, what is your best way of spending free time or weekends?

My favourite way of spending free time is with my family, my wife and two sons. We go for walks together, we read, we play games, logic games, of course − with their dad a physicist the games must be ambitious to help them develop. We also like to play music together, my children are learning to play the violin and I’m learning with them. I used to think that the violin was not an instrument for mere mortals but when I saw that the boys have been learning since the age of three with the Suzuki method and are able to play something then I thought that maybe it is for people after all. I also like DIY so when I can fix something at home by myself, I do so with pleasure. I also get satisfaction from making small things by myself. You can buy everything these days but when you make something yourself then any time you walk past it and look at it, it makes you happy.

Thank you for the interview, Professor.

Thank you very much.

Sopot, 31 March 2016

Interview: Dr Tadeusz Zaleski
Photos: Piotr Pędziszewski