A tiny oscillating crystal weighing little more than a grain of sand has become the heaviest object ever recorded in a superposition of sites.
Physicists at the Swiss Federal Institute of Technology (ETH) in Zurich have attached a mechanical resonator to a type of superconducting circuit commonly used in quantum computing to replicate Erwin Schrödinger’s famous thought experiment on an unprecedented scale.
Ironically, Schrödinger would be somewhat skeptical that anything so large—well, anything at all—could exist in an ambiguous state of reality.
Superposition states are unparalleled in our everyday experience. Watch the soccer ball drop, and you can track its fall rate with a stopwatch. Its final resting position is as clear as day, and even how it rotates in flight is evident.
If you close your eyes when they fall, there is no reason to think that these states of location or behavior could be any different. However, in quantum physics, features like position, spin, and momentum don’t exist in any meaningful way until you see a ball resting on the ground.
Along with another heavyweight of theoretical physics, Albert Einstein, Schrödinger wasn’t entirely keen on interpretations of experiments indicating that particles lacked precise properties until observation gave them one.
To show how absurd the whole idea was, the Austrian Nobel laureate described a scenario where the unobserved location of a particle was linked to the life of an invisible cat.
Imagine, if you will, that a particle spat out randomly from a decaying atom, hits a Geiger counter, causing the vial of poison to shatter, and instantly kills a cat. Since all of this takes place inside a box, the events and their timing remain unnoticed.
Go with what is known as Copenhagen Interpretation In quantum physics, the invisible system exists in a state of all possibilities until its final state is observed. The particle is emitted and not emitted. Geiger counter active and inactive. The poison vial is broken, not shattered. And the cat is alive and dead.
This deadly camouflage is almost impossible to visualize but is easily represented in Schrödinger’s wavelike equation.
Nearly a century later, Schrödinger’s is no longer a joke. It has been observed not only in small molecules but in entire molecules (not to mention groups of thousands of atoms). We can manipulate the box to ensure the cat never dies. We can even tinker with the setting to separate the cat. In fact, entire technologies are founded on the same principles as objects in superposition states.
Although no actual cats have ever been threatened by a quantum experiment—because morals, you know—the theory remains straightforward. Large objects like cats, or indeed, humans, elephants, or even dinosaurs, can exist in superposition states in the same way as electrons, quarks, and photons.
The mathematics leaves no room for doubt, however, observing the effects of such a hazy presence on such a large scale is another story entirely.
At the atomic level, a tinge of unfulfilled destinies can be seen with fairly primitive equipment. As the properties of objects grow, it becomes more difficult to empirically elicit the signatures of superposition.
In this last experiment, the resonator of high-pitched sound waves, or habar, as a cat 16.2 µg. What it lacks in whiskers and fish puffs, it makes up for in the fact that it can hum over a short range of frequencies when powered by a current.
“By superimposing the two states of oscillation in the crystal, we have effectively created a Schrödinger’s cat weighing 16 micrograms,” He says Lead author and ETH Zurich physicist Yiwen Chu.
For the roles of the radioactive atom, Geiger counter, and poison, Team A senda superconducting circuit that served as the power source for the experiment, the sensor, and the superposition.
Connecting the two together allowed the researchers to set the HBAR in motion so that its vibrations trembled in two phases simultaneously, a phenomenon that was back in transmission.
How big future experiments might go is an open question. In practice, pushing the limits of size on superposition may lead to new ways to make quantum technology more powerful or form the basis of more sensitive tools for studying matter and the universe.
Basically, there are still questions about what it means for matter to be in superposition at all. Despite decades of progress in making quantum mechanics more precise, there is It is still not clear Why opening the box should make any difference to the fate of Schrödinger’s cat.
What it means to turn maybe into reality remains as much a particle physics mystery as when Schrödinger dreamed up his preposterous idea of a cat that shouldn’t be.
This research has been published in Sciences.