You might be familiar with the qubit, the fundamental unit of quantum information.
But theres also a qudit, a different way of storing and making use of quantum information.
Muschiks new paper comes on the heels of a 2021 paper on the same subject,publishedin PRX Quantum.
An artist’s concept of elementary particles.Illustration: Harald Ritsch
Below is our conversation, lightly edited for clarity.
Christine Muschik: We want to make computing as efficient and as powerful as possible.
So thats the overarching mission, to make computing as powerful as possible.
But the philosophy is the same.
You have zero and one, and thats how you process your information.
Now you have qudits, with a Dbecause why do we stop at two levels?
Couldnt we just go on?
We started with a qutritjust one more levela single information carrier is now three levels, three possible states.
Christine Muschik:you might fit more information by using more levels, but not exponentially more.
Gizmodo: How does that change the operation of a quantum computer?
Christine Muschik:Theres a price to pay, and then theres the reward that we reap.
The most important thing is that your circuit complexity shrinks.
Thats our headache, and why we dont sleep properly.
Everything is more efficient, and you get your result more quickly and with less noise.
How did it move the needle on this idea?
But its really hard to do on a quantum computer.
You have a lot of noise.
I would argue our outcomes moved the needle two-fold.
We could simulate fundamental particle interactions beyond 1Dthat was the first thing we set out to do.
But accidentally, we also accomplished something else: the first full qudit algorithm.
We put everything together and took it for a drive, a whole algorithm.
Now you have a computing capability we can apply this to now.
Gizmodo: I was going to ask you about applications now that, now that youve derived this.
Its also extremely useful in quantum enthusiasts notion of the quantum internet that people attempt to build.
you’re free to make information more secure in quantum communication.
And also what is missingthere are gaps, holes, and in some cases canyons of missing information.
For qudits, how do you do error mitigation, optimal control, error correction?
Theres so much to figure out.
Christine Muschik:All our quantum computers are, like, really proof of concept.
Theyre small and noisy.
Were very limited by what we can do.
We can demonstrate that it works, but we cannot outperform the strongest classical computers.
We cannot even outperform my laptop.
But once we build [a quantum computer] theres nothing blocking it.
Gizmodo: You mentioned that qudits should be in the game when were talking about particle collisions.
Other strategies or quantum computing approaches are being workshopped that might compete in that space?
Christine Muschik:Oh theyre very, very compatible.
I call it a seamless merging opportunityyou can really plug and play according to what you need.
One ingredient is matterin our case, we had electrons and positrons.
But force fieldswhat some call quantum gauge bosonsnaturally have many different levels.
You make everything super inefficient if you venture to describe these force fields with two-level systems.
We could get a lot more efficiency using qudits for that.
Your infrastructure is the same, you just decide what you want to use.
Gizmodo: What are your teams next steps, and the next step for qudits in general?
What does this mean for quantum physics more generally?
What we need to do next is we need to go to three dimensions, right?
We also want to go to more complicated theories.
We talked about electrons and positrons and how they interact.
But next we want to include quarks and gluons.
A few weeks ago we dove into quantum sensing with qudits.
And we also need to investigate how to do better error correction on these qudits.
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