Two groups of physicists, working independently, claim to have reached a final verdict on the so-called wave / particle duality.From Newton to Maxwell, the light was always considered as a wave. It was Einstein who won the Nobel Prize in Physics demonstrating the photoelectric effect, the explanation of which depends on the photons are seen as particles.
And then there might arise throughout quantum mechanics, which states that the photons, the fundamental elements of light, just like any other “quantum system” can be both particles and waves.
However, discussions on the subject were never suspended because the result – wave or particle – depends on how the measurement is performed.Measure a photon in a way, and he will tell you that it is a particle. Change the measurement, and transmute it into particle.
This created currents among physicists who would like to find an answer “more fundamental” – some arguing that photons are essentially particles and others arguing that they are essentially waves.
What these currents are seeking is the “true nature of light”, because it seems too weird to have to assume that “a thing can be both.”
The two streams assume that the photon is in its second transmute personality under conditions to be specified or discovered yet.
Particles and waves simultaneously
The equations of quantum mechanics, however, quietly seated on a history of extreme success, predict that a particle can be in different places at the same time.In fact, the particle can be even infinite places at once – like a wave. And not just “looking” with a wave, but actually “being” a wave.
What two groups of physicists could now do was to demonstrate experimentally that this game has even finished a draw.
Similar experiments were performed by Alberto Peruzzo and colleagues at the University of Bristol, UK, and Florian Kaiser and colleagues at the French CNRS institute.For the first time, the physical could not observe photons as particles oras waves but as particles and as waves at the same time.Far from being a scientific curiosity, the experiment will have broad implications for all quantum systems, among which the qubits used for quantum computing , the processors photonic and optical fiber communications.
The observation of dual particle / wave is based on a proposal made by the physicist John Wheeler in 1980.The experiment consists in dividing the photons and then bring them together again.Splitting a wave is trivial, but it should not be possible to split a photon-particle.The measurement employs two interferometers, the first dividing the light wave and the second bringing it back, and seeing what happens.
When a photon shot individually, through the first interferometer, the result remains the second interferometer an interference pattern, typical of waves that merge, but never particle – even though the photon can not be split. Thus the famous duality is demonstrated.
But what is missing is to see how and when a photon “becomes” particle, or “flips” wave.For this, the two groups devised variations of the experiment Wheeler allowing the photon to be tracked all the time and continuously measured.
Schrodinger’s Cat undecided
Both teams used slightly different configurations, but both used pairs of entangled photons, those that Einstein called spooky , because what happens to one affects the other, regardless of the distance that separates them.A photon is observed and detected in an interferometer, while the other photon “decides” if the measurement is done in order to result in particle or wave – remember that the type of measurement determines whether the photon as a particle or as answer wave.
Like what happens to a photon always interferes with her partner interlaced, scientists can observe the photon continuously metamorphosing between particle and wave.
That’s because the two make up the strange situation known as Schrodinger’s Cat– a cat kept inside a box with a vial of poison whose opening is determined by the behavior of the quantum particle, will be alive and dead at the same time, because the condition of the particle will only be set when it is measured, i.e., when the box is opened.
Even if the control photon decide how to measure the particle after it has passed the first interferometer, she remains “undecided”, maintaining its dubious nature.
In terms of Schrodinger’s Cat, that means that even after that should already be set if the cat is alive or dead, is still possible to determine whether he is alive ordead, or if he is still alive and dead at the same time.
The advantage of experiments is that, instead of individual measurements, they make exploring the “passage” of wave-like behavior of light to a particle-like behavior – a “ticket” that is constant.
Since, in the experiments, the situation is repeated infinitely, it is possible to note that the photon constantly assumes two conditions – that is, the photon is even a particle and a wave at the same time.Quantum mechanics struck again, further reinforcing its weird, but very effective, to explain nature.