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Thursday, 20 June 2019

Physicists predict quantum leap and save Schrodinger's cat

Physicists say it is possible to predict the quantum leap, contrary to a theory accepted for decades. [Image: Kat Stockton]

How to Save the Cat from Schrodinger

A team of physicists from Australia, USA and France discovered how to save Schrodinger's famous cat , the symbol of quantum superposition and the unpredictability of nature on an atomic scale.

The discovery will allow researchers to create an early warning system for quantum leaps that occur between qubits, the fundamental elements of quantum computing , and cause them to lose their data.

Schrodinger's cat is a well-known paradox, used to illustrate the concept of superposition - the ability of a particle to exist simultaneously in two different states - and the unpredictability, well expressed in the well-known Heisenberg Uncertainty Principle .

To illustrate these principles, physicist Erwin Schrodinger (1887-1961) devised a mental experiment in which a cat would be placed in a sealed box, along with a radioactive source and a poison that would be released if an atom of the radioactive substance decayed - decay is a typical quantum phenomenon.

The superposition theory suggests that until someone opens the box, it is not possible to know whether the atom has decayed or not - in other words, the cat will be alive and dead at the same time in a superposition of states, as well as the particle that determines your destiny. Opening the box to observe the cat causes it to abruptly change its quantum state, which will then collapse into a dead or alive situation.

Quantum leap

Now, Zlatko Minev and his colleagues decided to take a closer look at the actual functioning of the mechanism that dictates this change of state, the famous quantum leap. The quantum leap is the discrete (non-continuous) and random change in the state of an atomic particle, which only "realizes" when it is observed, when its wave function collapses.

What they have discovered is that it is possible to anticipate the quantum leap that will determine the changing state of the decaying radioactive particle and the action of releasing the venom. More than that, it is possible to act in real time to save the cat, which overthrows decades of a fundamental dogma of quantum physics.

The experiment showed an increase in coherence during the jump - rather than the decoherence - even when the phenomenon was observed, which typically destroys quantum coherence. With this, it is possible to reverse the jump.

Thus, the results contradict the view established by the Danish physicist Niels Bohr (1885-1962), stating that quantum leaps are neither abrupt nor as random as previously thought.

The experiment consisted in monitoring an artificial superconducting atom using three microwave generators radiating the atom, which is trapped in a 3D cavity made of aluminum. [Image: Minev et al. - 10.1038 / s41586-019-1287-z]

Quantum computers

For a tiny object, such as an electron, a molecule, or an artificial atom containing quantum information - that's why they function as qubits - a quantum leap is the sudden transition from one discrete energy state to another.

Because in the development of quantum computers, qubit jumps manifest themselves as errors in calculations - the change of state means that the qubit has lost its data - this finding simply says that it is possible to act against these errors, canceling them at source, so they occur.

This is also a crucial point for theory, researchers say, because although quantum jumps appear discrete and random in the long run, reversing a quantum leap means that the evolution of the quantum state has a deterministic character in part, and random - the jump always occurs in the same predictable way from its random starting point.

"The quantum leaps of an atom are somewhat analogous to the eruption of a volcano, and they are completely unpredictable in the long run. However, with proper monitoring, we can detect early warning of an impending disaster and act before it occurs , "said Minev.


 To catch and reverse quantum jump mid-flight Zlatko K. Minev, Shantanu O. Mundhada, Shyam Shankar, Philip Reinhold, Ricardo Guti√©rrez-J√°uregui, Robert J. Schoelkopf, Mazyar Mirrahimi, Howard J. Carmichael, Michel H. Devoret Nature
DOI: 10.1038 / s41586-019-1287-z

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