Fast Fourier Transform, Quantum Fourier Transform, Next Quantum Algorithm…

**Quantum interference in the service of information technology**

Excerpts and salient points ~

+ Scientists from the Faculty of Physics, University of Warsaw, in collaboration with the University of Oxford and NIST, have shown that quantum interference enables processing of large sets of data faster and more accurately than with standard methods. Their studies may boost applications of quantum technologies in artificial intelligence, robotics and medical diagnostics, for example.

* In their article published in Science Advances, scientists from the University of Warsaw—Dr. Magdalena Stobinska and Dr. Adam Buraczewski, scientists from the University of Oxford, and NIST, have shown that the simplest quantum gate, which interferes between two quantum states, essentially computes the Kravchuk transform.*

+ [T]he simplest quantum gate, which interferes between two quantum states, essentially computes the Kravchuk transform. Such a gate could be a well-known optical device—a beam splitter, which divides photons between two outputs. When two states of quantum light enter its input ports from two sides, they interfere. For example, two identical photons, which simultaneously enter this device, bunch into pairs and come out together by the same exit port. This is the well-known Hong-Ou-Mandel effect, which can also be extended to states made of many particles. By interfering “packets” consisting of many indistinguishable photons (indistinguishability is very important, as its absence destroys the quantum effect), which encode the information, one obtains a specialized quantum computer that computes the Kravchuk transform.

+ Most importantly, such a computation of the quantum Kravchuk transform always takes the same time, regardless of the size of the input data set. It is the “Holy Grail” of computer science: an algorithm consisting of just one operation, implemented with a single gate.

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