University of Twente Research: Fifty Perfect Photons is Feasible

Fifty perfect photons for ‘quantum supremacy’

Excerpts and salient points ~

+  The first proof of ‘quantum supremacy’ is already there, done using superconducting qubits and on very complicated theoretical problems. About 50 quantum building blocks are needed as a minimum to make the difference. This is the same if you would use photons instead of qubits. Using photons may have advantages over qubits: they can operate at room temperatures and they are more stable. There is one important condition: the photons have to be perfect in order to get to the critical number of 50. In their new paper, UT scientists demonstrate that this is feasible.

Fifty is a critical number for quantum computers capable of solving problems that ‘classic’ supercomputers cannot solve anymore. Proving ‘quantum supremacy’ requires at least 50 so-called ‘qubits’. For quantum computers working with light, it is equally necessary to have at least 50 photons. And what’s more: these photons have to be perfect, or else they will worsen their own quantum capabilities.

+  The main cause of imperfection, however, is that the light source produces photons that are slightly different, while in fact they should be perfectly the same. Imagine a photon pair that comes out of the light source, of which one is red and the other is a bit more orange. They have a lot, but not enough, in common. Using a filter to make them both red seems obvious. But you will lose part of the photon, thus making quantum calculations impossible as the imperfections remain coupled. Or, even if the system can deal with some imperfection, the number of 50 is never reached: off goes supremacy.

+  The researchers went back to basics: to the light source, for finding out if there is room for improvement. They would like to improve the crystal structure of the light source. By ‘playing’ with the preferred orientation in the crystals, and by dividing them into domains, it is possible to exactly give light the desired properties.

Source:  University of Twente.  W.R. van der Veen (Wiebe),  Fifty perfect photons for ‘quantum supremacy’…

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