actually done this particular experiment trying to put as many entangled particles no no in part because in part because it's hard it's hard but there are you know sort of the state of the art there are a couple of physical systems where people have done things like this for what's around NUMBER_TOKEN um spins right so that's kind of the state of the art so you can go beyond just a single um spin or cubit in a superposition of zero and one um you could scale it up to about NUMBER_TOKEN and i'm sure this will keep getting pushed um uh and well this is what we we need to push for quantum computers right when you say NUMBER_TOKEN qubits i mean that's a NUMBER_TOKEN cubit quantum computer is is we we haven't had anything more than that i guess is what you're saying um yeah so i mean i guess you you know if you read the news you know they're NUMBER_TOKEN-ish cubit quantum computers um depending you know what you define as a quantum computer but um yeah um yeah so and what exactly is the kind of system that you're working with i mean you gave us some some kind of conceptual things but what what happens in your lab when you're pushing these bottom systems around yeah great so so what do we do in my lab so first of all um the general system i work with are systems of laser-cooled atoms um and so um perhaps it's a little counter-intuitive we can use lasers to bring atoms to temperatures that are sort of in our lab millionths of a degree above absolute zero i mean maybe it's worth explaining a little bit about that when i think of shooting a laser at something it sounds like i'm going to heat it up but you're somehow cooling it down yeah yeah exactly um so so there's a trick we use um which basically relies on the doppler effect so you know i wish i could wave my arms and the listeners of the podcast they can imagine the basic picture you can have in mind is we have some atoms flying around you know they're initially at room temperature and we have um uh laser beams basically that are um counter propagating so if we want to slow the atom down in a particular direction we would have two laser beams that are pointing in opposite directions and um instead of tuning those laser beams so that they can resonantly be absorbed by the atoms we tune them so that they're like a little bit too low in energy or too low in frequency to be on on resonance with the atoms um but there's a this phenomenon of the doppler effect it's the same thing where you know if i'm sort of driving along the highway and a truck comes the other other way you know the faster it's moving the more it's kind of frequency will be shifted upward um sound higher pitched in the same way to the atom depending which way it's moving the sort of laser beam will seem like it's higher pitched or at a higher frequency and this results in a phenomenon where the atom is more likely to absorb a laser beam that's propagating in a way that will kick it to slow it down then a laser beam that's propagating in the in the other direction um and so so that basically means you get this preferential absorption of photons that slow
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