In quantum mechanics, Schrodinger’s cat is a famous paradox that applies the concept of superposition in quantum physics to objects encountered in everyday life. Schrodinger’s cat was a thought experiment envisioned by Erwin Schrodinger, the man who formulated the wave equations to describe the wave function or state function of a quantum mechanical system. The idea is that a cat is placed in a sealed box where a radioactive source and a poison were also there. The poison will be triggered if an atom of the radioactive substance decays.
Now, quantum physics will say that the cat is both alive and dead at the same time. Until someone opens the box and in doing so, changes the quantum state, the cat inside remains in the dead and alive state forever. The question arises how can the cat be dead and alive at once? Schrodinger had an explanation to it. The radioactive decay, which triggers the poison to come out and kill the cat, is a random process and there is no way to predict when exactly it will happen. Physicists say that atom exists in a state known as superposition, which is both decayed and not decayed at the same time. Until the box is opened, an observer can’t say whether the cat is dead or alive as the cat’s fate is tied intrinsically to whether an atom has decayed or not and the cat would, according to Schrodinger, be living and dead in equal parts. This paradox was to explain the atomic system in quantum terms. The atoms, as per the quantum theory, remain in discrete energy state or quanta and are subjected to random jumps from one quantum state to another.
A research team from the Yale University and the University of Auckland has figured out the way to catch Schrodinger’s cat by anticipating its jump and save it from the proverbial doom. The discovery also enables scientists to anticipate the imminent jumps of atoms from one quantum state to another.
Quantum jumps of atoms were theorised by Niels Bohr a century ago and was published in the “London, Edinburgh and Dublin Philosophical Magazine and Journal of Science” in 1913 and an excerpt can be found here. But Bohr’s theory of quantum jump could only be observed in the 1980s.
The new study ventured to find out the actual workings of a quantum jump for the first time. What the results reveal is surprising—it says that quantum jumps are neither abrupt nor as random as thought previously. The study was conducted on qubits—the artificial atoms that contain quantum information.
Professor Michel Devoret, the corresponding author of the study who belongs to Yale University, is quoted to have said—“These jumps occur every time we measure a qubit. Quantum jumps are known to be unpredictable in the long run.”
Dr. Zlatko Minev, another lead author who also belongs to Yale University says—“Despite that, we wanted to know if it would be possible to get an advance warning signal that a jump is about to occur imminently.”
The scientists developed a special approach to indirectly monitor a superconducting artificial atom, with three microwave generators irradiating the atom confined in a 3D aluminium cavity. The artificial atom has the quantum information.
Their monitoring method allowed them to observe the atom with unprecedented efficiency. The microwave radiation on the other hand, stirs the artificial atom resulting in quantum jumps while it is being monitored simultaneously. The quantum signal of the jumps could be monitored in real time.
This set up enabled the physicists to see a sudden absence of photon detection—this tiny absence is an advance warning of a quantum jump of the atom.
Implications for Quantum Computers
The speciality about quantum computers is their qubits. The qubits are analogous to the bits that the current computers have. A bit can be either zero or one. But qubits, which have quantum characters, exist in more than one state at a time as observed. The quantum jumps of these qubits, as thought earlier, are random and as a result quantum computation can have more than one outcome. This was a fundamental problem in the world of quantum computing.
The new experiment succeeds in not only predicting an imminent quantum jump, but also means that one can reverse it to stop unwanted outcomes.