Researchers build transistor-like gate for quantum information processing – with qudits

Phys.org ^ | 07/16/2019

[BenLurkin]

The more entanglement in the so-called Hilbert space—the realm where quantum information processing can take place—the better.

Previous photonic approaches were able to reach 18 qubits encoded in six entangled photons in the Hilbert space. Purdue researchers maximized entanglement with a gate using four qudits—the equivalent of 20 qubits—encoded in only two photons.

In quantum communication, less is more. "Photons are expensive in the quantum sense because they're hard to generate and control, so it's ideal to pack as much information as possible into each photon," said Poolad Imany, a postdoctoral researcher in Purdue's School of Electrical and Computer Engineering.

The team achieved more entanglement with fewer photons by encoding one qudit in the time domain and the other in the frequency domain of each of the two photons. They built a gate using the two qudits encoded in each photon, for a total of four qudits in 32 dimensions, or possibilities, of both time and frequency. The more dimensions, the more entanglement.

Starting from two photons entangled in the frequency domain and then operating the gate to entangle the time and frequency domains of each photon generates four fully-entangled qudits, which occupy a Hilbert space of 1,048,576 dimensions, or 32 to the fourth power.

Typically, gates built on photonic platforms to manipulate quantum information encoded in separate photons work only some of the time because photons naturally don't interact with each other very well, making it extremely difficult to manipulate the state of one photon based on the state of another. By encoding quantum information in the time and frequency domains of photons, Purdue researchers made operating the quantum gate deterministic as opposed to probabilistic.

[Bonemaker]

I left off with tubes and the early days of transistors. Still had IBM key cards. Only semi have kept up with advancements. But the tubes were so great and understandable.

[103198]

Two words...

Go Boilers!

[Bonemaker]

[Bonemaker]

Damnit!

[EQAndyBuzz]

“Typically, gates built on photonic platforms to manipulate quantum information encoded in separate photons work only some of the time because photons naturally don’t interact with each other very well, making it extremely difficult to manipulate the state of one photon based on the state of another. “”

Photons must learn to play together. I suggest doubling the qudit count within the space by a factor of 24 to the 6th power. If that doesn’t work, blame Deutsch’s algorithm, erase the board and go out for margaritas.

[epluribus_2]

The logic charts look just like the ones that had tubes implementing them. Just hundreds of thousands or Millions of them in one circuit.

[IronJack]

Photons are expensive in the quantum sense

Maybe, but WalMart has them on sale this week for 50 percent off with a coupon.

[epluribus_2]

We could have done deep learning neural networks AI in the sixties but it would have taken the electric power of the city of Cleveland. And finding the one bad tube would have been a bXXch.

[Dave Wright]

The research is interesting from the standpoint of being able to exploit the photons multiple independent degrees of freedom and complex amplitudes at the same time for holding information. As the authors state in the paper though, they can only resolve these quidits 90% of the time so it doesn’t seem like it has any practical uses at least at this point.

[Larry Lucido]

Photons are expensive in the quantum sense because they're hard to generate

We need more fotomats.

[ProtectOurFreedom]

Jet wait for Hilbert Space 2.0. They’ll run like a dream.

[Getready]

Is the gate operational...have they teleported real info? If one could hack the sending unit...you might instantly know the message...no?

[libertylover]

Purdue researchers maximized entanglement with a gate using four qudits—the equivalent of 20 qubits—encoded in only two photons.

Is that kind of like a tire with a "2-ply, 4-ply rating"?

[Chode]

if they can build this stuff, why can't they show us a picture of it???

[Vaquero]

[NativeSon]

Did you just assume that photon ‘s quantum state?

[SunkenCiv]

Thanks BenLurkin.

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[stevio]

My mother started her career wiring tubes with Western Electric. Ended with AT&T and printed circuit boards. With her persuasion, I got into the biz now doing 5nm layout. In her elder years she likes to ask me “Are they still making them smaller and smaller?”. Yes they are Mom.

[Bonemaker]

That technology changed REAL FAST!Good that you and your mother kept up with it.