A team of Yale University researchers has revealed that Schrödinger's cat can exist - alive or dead - in two boxes at once. The findings could help physicists advance their understanding and development of quantum computing.
Schrödinger's cat is a hypothetical experiment that involves the concept of superposition in quantum physics and applies to objects in everyday life. The unique paradox places a cat in a sealed box with a radioactive source and a poison that is only triggered by the decaying of an atom of the radioactive substance.
Quantum physics suggests that the cat is a superposition of states - alive and dead - until the box is opened, which ultimately changes the quantum state.
Now, the new study reveals a new type of Schrödinger's cat-like state that lives or dies in two boxes simultaneously. This new experiment takes the previous paradox and integrates the process of entanglement, another concept central to quantum physics that allows for the instantaneous change of a distant object through observation.
In the new experiment, the team created a device consisting of two 3D microwave cavities and an additional monitoring port, with the "cat" in each of the cavities composed of confined microwave light. A superconducting artificial atom connected all of the devices in the experiment to each other.
"This cat is big and smart," said Chen Wang of Yale University and first author of the study. "It doesn't stay in one box because the quantum state is shared between the two cavities and cannot be described separately. One can also take an alternative view, where we have two small and simple Schrodinger's cats, one in each box, that are entangled."
The new experiment could help scientists create quantum computers that better harness the concepts of superposition and entanglement and ensure that the devices can correct errors without interfering with information, a big hurdle in the development of quantum computers.
"It turns out 'cat' states are a very effective approach to storing quantum information redundantly, for implementation of quantum error correction," said Robert Schoelkopf, also of Yale University and co-author of the study. "Generating a cat in two boxes is the first step towards logical operation between two quantum bits in an error-correctible manner."
The findings were published in the May 27 issue of the journal Science.
