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Quantum information processing promises to be much faster and more secure than what today's supercomputers can achieve, but doesn't exist yet because its building blocks, qubits, are notoriously unstable.
Purdue University researchers are among the first to build a gate - what could be a quantum version of a transistor, used in today's computers for processing information - with qudits. Whereas qubits can exist only in superpositions of 0 and 1 states, qudits exist in multiple states, such as 0 and 1 and 2. More states mean that more data can be encoded and processed.
The gate would not only be inherently more efficient than qubit gates, but also more stable because the researchers packed the qudits into photons, particles of light that aren't easily disturbed by their environment. The researchers' findings appear in npj Quantum Information.
The gate also creates one of the largest entangled states of quantum particles to date - in this case, photons. Entanglement is a quantum phenomenon that allows measurements on one particle to automatically affect measurements on another particle, bringing the ability to make communication between parties unbreakable or to teleport quantum information from one point to another, for example.
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.
[...] Next, the team wants to use the gate in quantum communications tasks such as high-dimensional quantum teleportation as well as for performing quantum algorithms in applications such as quantum machine learning or simulating molecules.
(Score: 3, Interesting) by Rupert Pupnick on Monday July 22 2019, @03:46PM
As a Quantum Computing Skeptic, I'm hardly an expert in the field, but this is simply bad tech journalism that, for one thing, severely misrepresents classical computing concepts I actually do understand.
Let's start with transistors and gates. A gate (I presume the author here means a logic gate) is made up of transistors-- they aren't "versions" of each other. At best you can make a gate that does logical inversion using one transistor. Anything more complicated than that and you're going to use more than one transistor to make a logic gate.
Next, let's talk about qubits. A qubit is really a mathematical abstraction (see https://en.wikipedia.org/wiki/Qubit [wikipedia.org]), just like a regular classical bit is an abstraction. It's not a physical thing, it's a representation of how data is stored. As everyone knows, it's either a 1 or a 0. If you look at the Wiki link, the qubit definition operates at a similar level of abstraction, but it's much more complex. It can be visualized as the surface of a unit sphere having opposite poles that represent the states of 1 and 0. All other points represent probability distributions of which there are an infinite number.
After the article explains what a qudit is, we have a breezy characterization of better "stability" and "efficiency" (whatever that means in a quantum context), which are really characteristics of physical implementation ("packed into photons".. don't they mean "made of photons"?).
A qudit, from what I understand, is the quantum equivalent of 3 state signaling in classical computing. You can make something with more "information potential" than a qudit with two qubits. But does it make sense to use a more complicated building blocks like this to build a quantum gate or computer? Why?
All very confusing, and not credible IMO.