Here\u2019s what you\u2019ll learn when you read this story:<\/p>\n
Schr\u00f6dinger\u2019s Cat is a famous thought experiment that explains the non-classical weirdness of quantum superposition.<\/p>\n<\/li>\n
For decades, physicists have theorized that more Schr\u00f6dinger\u2019s Cat states exist beyond simple position or velocity, but these theories haven\u2019t been recreated in a lab.<\/p>\n<\/li>\n
Now, scientists at Oxford University say they\u2019ve created new exotic superpositions by capturing a single ion of strontium-88 confined in an ion trap, a breakthrough that could help improve quantum computing and error correction.<\/p>\n<\/li>\n<\/ul>\n
Quantum physics is the ultimate challenge to humanity\u2019s classical intuition. During a 1964 lecture at MIT<\/a>, physicist Richard Feynman famously remarked, \u201cI can safely say that nobody understands quantum mechanics.\u201d It\u2019s precisely this unintuitive weirdness that\u2019s driven physicists over the decades to rely on handy metaphors when explaining one of quantum mechanics\u2019 core principles: superposition.<\/p>\n The most famous of these metaphors is Schr\u00f6dinger\u2019s Cat,<\/a> a thought experiment first put forward by Austrian theoretical physicist Erwin Schr\u00f6dinger in which a cat, a radioactive isotope with a 50\/50 chance of decaying, a Geiger counter, a flask of poison, and a triggering mechanism are placed in a sealed box. If the Geiger counter detects radioactive decay, the flask is broken, the poison is released, and the cat dies (disclaimer: no felines were actually harmed in the making of this thought experiment). If the radioactive isotope doesn\u2019t decay, the cat lives.<\/p>\n The significance of this metaphorical setup is that it\u2019s mathematically similar to the idea of quantum superposition<\/a> and the quantum collapse of the wave function<\/a>. Until the box is opened, we can\u2019t know whether the radioactive isotope has decayed, so the cat in the box is therefore both alive and dead from our perspective. But once an observer makes a measurement (i.e. opens the box), the \u201cwave function\u201d of this superposition of states collapses. After the box is opened, the cat can only be in one state or the other\u2014it\u2019s either dead or alive.<\/p>\n The seeming paradox of Schr\u00f6dinger\u2019s cat<\/a> being both alive and dead is analogous to the problem of superposition in subatomic particles, which can appear to be in two states at once until they\u2019re measured. For decades, however, scientists have theorized that more complex variations of Schr\u00f6dinger\u2019s famous thought experiment might exist beyond the simple \u201calive or dead\u201d scenario. Now, a study led by scientists at Oxford University has successfully demonstrated these exotic variations in the lab by using a single ion of strontium-88 confined in an ion trap. By manipulating both the ion\u2019s internal quantum state (i.e., its spin) and its motion\u2014the latter behaving as a quantum oscillator\u2014the researchers created superpositions involving multiple quantum properties, not just two opposing states. The results of the study were published in the journal Physical Review X<\/a>.<\/p>\n \u201cThis approach gave us a tool to sculpt quantum superpositions into almost any shape,\u201d Oxford physicist Sebastian Saner, lead author of the study, said in a press statement<\/a>. \u201cThe states we produced exhibit rotational symmetries and form striking geometric interference patterns.\u201d<\/p>\n These different states primarily arise from how the uncertainty of the quantum structure is distributed or how it\u2019s placed in phase space, according to the press statement. With two degrees of freedom\u2014provided by the internal quantum state and the ion\u2019s motion\u2014researchers could essentially sculpt the motional state of the ion. The authors explain that this allowed them to tune the size, phase, and separation of the varying components while also switching between other non-classical states, including squeezed<\/a>, trisqueezed, or quadsqueezed states in a single superposition.<\/p>\n This isn\u2019t just an interesting theoretical discovery. These new quantum states could improve upon the two-level quantum bits found in current quantum technologies while also improving methods for quantum error correction.<\/p>\n