Researchers at the Max Planck Institute for Quantum Optics in Garching, Germany, have succeeded in creating Schrödinger-cat states using a single rubidium-87 atom in an optical cavity to control a propagating light pulse. The feat could help advance the field of quantum state engineering with possible applications in quantum networks and quantum computing.
In 1935, physicist Erwin Schrödinger devised his famous thought experiment involving a cat that could, surprisingly, be both dead and alive at the same time. In his gedanken, the decay of a radioactive atom triggers a mechanism (the breaking of a vial containing a poisonous gas) that kills the cat. However, since the decay of the radioactive atom is a completely random and quantum phenomenon, we cannot know the moment at which the cat dies. Mathematically, the feline is in an entangled superposition of quantum states – known as the “Schrödinger-cat” state.
Recreating this state is no easy task, but researchers have managed to do this in recent years using the quantum superposition of coherent states of a laser field with different amplitudes, or phases, of the field. They have also created these states using a trapped ion (with the vibrational state of the ion in the trap playing the role of the cat) and coherent microwave fields confined to superconducting boxes combined with Rydberg atoms and superconducting quantum bits (qubits).
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