Two of the worlds most prominent tech companies Google and IBM are competing to entangle more photons in a race to exceed our current rate of information processing by several orders of magnitude. Google has reached the highest entanglement at 72 cubits or 144 photons for their Bristlecone. In so doing have passed IBMs previous record of 50 qubits.
One of the reseaches was quoted saying
“If a quantum processor can be operated with low enough error, it would be able to outperform a classical supercomputer on a well-defined computer science problem, an achievement known as quantum supremacy.”
“Quantum Supremacy” is a term used by tech companies to describe the point at which one Quantum Computer exceeds all the information processing power on the planet.
“Although no one has achieved this goal yet, we calculate quantum supremacy can be comfortably demonstrated with 49 qubits, a circuit depth exceeding 40, and a two-qubit error below 0.5%. We believe the experimental demonstration of a quantum processor outperforming a supercomputer would be a watershed moment for our field, and remains one of our key objectives.”
Most people think that will be around 100 Qubits. If it were as simple as entangling more photon pairs we’d almost be there by now, but we also have to maintain the extreme temperatures that enable quantum effects to exist at a large scale. That is why entanglement up to this point had only been conserved for microseconds. Some exotic states of matter contend with this notion however hinting at the possibility of lower temperature quantum tech.
For now Quantum computing appears to require temperatures that approach absolute zero depending on the element used. That means that companies must power a superconductor with an electromagnetic field long enough to preserve extremely cold subatomic “circuit boards”. A prerequisite for this type of useful simultaneous non local information processing to take place in machines.
So you can expect that as superconducting electromagnets become more effective at taming exotic states of matter so to will quantum computers eventually improve in reaction. It all depends on how quickly we convert scientific principle to formal application. In other words how do we account for the new environment of quantum mechanics cryptographically?
It is likely that at first we will have quantum processors for ordinary computers to plug in to. Potentially improving speed to the degree of a modern supercomputer now. Simplifying an infrastructure for translation to normal computer programming languages like Python or C++ may be a good start. But the reality is that IBM and Google remain tight lipped on their actual operations.
Based on the science the most common contender for next gen quantum computing are time crystals and (EDIT) entangled clouds of bose einstein condensate.