I will try to bring a new technology to communication and information processing a little closer

in the next half to three and a half hours in the subject of quantum light as an information carrier.

I am of course aware that this is a topic that is not easy to digest now,

but I hope that when you go home you will find something to eat,

that when you go home you have taken something with you and say,

at least I have an impression of what it is about.

As usual, I start with an introduction to a scientific lecture

and I would like to prepare you a little bit about the different topics I want to talk about.

First, of course, I have to introduce the topic, and introducing it will be a historical introduction.

It's actually not that much about quantum information,

it's actually about the history of quantum physics or maybe something specific about quantum optics.

And I hope that you will see some basics that led us to the concept or the topic of quantum information.

The second chapter will be exactly about the topic, what is quantum information

and especially what is quantum information compared to classical information.

So what could it be, where can this quantum character,

which I will talk about a lot, manifest itself and what effects could it have?

And we are already coming to the third part of the lecture.

Where can this be applied? This is still future music, but not only.

We are actually already able to use certain parts of technology today,

and I will try to give you an introduction to this and show you the basics.

Quantum communication or quantum information processing.

I will start with quantum communication.

The word is composed of two parts, the communication and the quantum information.

Communication, something technical, is nothing more than the transmission between a transmitter and a receiver.

And when I talk about information, I have to specify which information that is.

And the new thing about quantum communication is that we are no longer talking about normal information, but about quantum information.

When I say what information in general, I put forward the classic term of information

that we are used to in computer science and that has actually been kept completely normal in our everyday life,

everyone knows what a bit is. Bit is the smallest unit of classical communication.

And in general we also know that bit can have 0 and 1, and if I know what that is, then I have received information.

Quantum mechanics we do something very similar.

We are no longer talking about bits, but qubits.

Qubits simply stands for quantum bits.

And we look at how this bit state, states are 0 and 1, are changed.

And quantum communication does not allow us to have either or, so either 0 or 1, but and.

We have 0 and 1 at the same time.

And that has serious effects.

You can imagine that if you have not yet made a decision, you are not either on one side or on the other side,

but you are and at the same time.

We do something similar here in quantum physics.

Let me just start.

Translation of information between transmitter and receiver, a bit clearer shown.

We have the transmitter, and you see that we physicists sometimes like to talk about people.

We do not talk about the transmitter, but we always talk about Alice.

It is easier said than done.

Alice wants to send an abstract information to Bob.

But we are not talking about the receiver either, but about Bob.

Everyone knows who is meant by it.

And if she does that, she first needs a communication channel.

The communication channel that I am currently using is simply the acoustics.