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Hey everybody. It's a pleasure to have Eugene Doolsey here today at Seminar.

Eugene spent a certain amount of time in Jeff Kimball's group at Caltech doing some really important work

that I think it was for the early days of modern quantum optics.

He's been leading his own groups at Pour concentrates and Endmrock

for some time here, it was some sort of work he quite enjoyed.

No, I was in my first August and now opening.

Where he does this really exciting think to quantum

optics and executive hope to atomic gases amazing

rhetoric 키.

Hello.

Also.

Thank you.

It's a pleasure to be here Éona, this is.

the sixth segment here and the place is getting better and better.

So this will be probably a silent and usual one and a half hours or so here because I'll be talking about atoms.

Not exclusively on atoms but like in the atoms.

But let's just go through it and we will be talking about atomic ensembles.

And that's the information of one of the atomic ensembles, this rule in gas contained in this little glass cell.

We will be also talking about more familiar things like the many rays.

The general subject is can we make a measurement of the variables x and t which is not bound by this constant.

Any guesses?

No.

Yes.

Of course there is no violation of the classical quantum mechanics, some piece, some covalent ones.

But still it's true.

X and p can be measured with in principle unlimited accuracy.

And I hope to convince you that this is true.

So how does this all happen in textbook?

Let's say that we have an oscillator and this oscillator is represented by this vector and this vector rotates.

And when this vector rotates in the phase diagram then there is a cosine and sine component and one of them is associated with the coordinate.

Another one is the derivative of the coordinate which is the moment.

So nice and cool, you can measure x but at the same time you impose the back-action of the measurement on p.

Then the thing rotates and you keep measuring let's say in this laboratory frame x.

But now you are imposing the back-action in that literature and it goes and goes and files up and if you measure very strongly in the oscillator rotating frame you will get what you deserve which is the level of back-action.

And yet as I said arbitrary small displacements in both position and momentum can be observed.

So the menu will be first I will talk about this subject that I call trajectories without quantum incentives with a negative mass reference very fast.

This will be sort of the general introduction and it's really undergraduate or maybe even high school algebra.

You need to know quantum incentives.

So then I will start talking about how to implement it in practice.

And the first story will be just about one quadrature of the oscillator. How to make a squeeze state of an oscillator by making stroboscopic measurements.

And then we will go further and discuss how to do what is promised here that is to measure x and p continuously.

And then there will be a bonus.

So just to give you a desert first.

Let's say you have a two-level atom. Let's say you have a collection of two-level atoms.

Let's say they are all initiated first in the alpha state.

Let's say now I am creating an excitation. I won't be a collective excitation when I explain to you other things.

In this level.

And I want to convince you that this corresponds to the oscillator with a negative mass.

So let's see how it works.