Have you ever been to more than one place at a time? If you are much larger than an atom, the answer will be no.
But atoms and particles are governed by the rules of quantum mechanics, in which several different possible situations can coexist.
Quantum systems are governed by a so-called “wave function”
And these different possibilities can coexist in a wave function such as what is called “superposition” of different states. For example, a particle existing in several different places at the same time is what we call “spatial superposition.”
Only when a measurement is made does the wave function “collapse” and the system finds itself in a certain state.
In general, quantum mechanics refers to the small world of atoms and particles. The jury still does not know what this means for large-scale sites.
In our study published today in Optics, we offer an experiment that can solve this thorny issue once and for all.
Erwin Schrödinger’s cat
In the 1930s, the Austrian physicist Erwin Schrödinger came up with his famous thought experiment for a cat in a box that, according to quantum mechanics, could be alive and dead at the same time.
In it, a cat is placed in a sealed box in which a random quantum event has a 50-50 chance of killing it. Until the box is opened and the cat is observed, and the cat is dead and live at the same time.
In other words, the cat exists as a wave function (with many possibilities) before being observed. When observed, it becomes a specific object.
After much debate, the scientific community at the time reached a consensus on “interpretation in Copenhagen”. This basically says that quantum mechanics can only be applied to atoms and molecules, but it cannot describe much larger objects.
It turns out that they were wrong.
Over the past two decades, physicists have created quantum states in objects made of trillions of atoms – large enough to be seen with the naked eye. However, it is not yet spatial superposition included.
How does the wave function become real?
But how does the wave function become a “real” object?
This is what physicists call the “quantum measurement problem.” It has puzzled scientists and philosophers for about a century.
If there is a mechanism that removes the potential for quantum superposition from large-scale objects, this will in some way require a “disruption” of the wave function – and this would create heat.
If such heat is detected, it means that large-scale quantum superposition is impossible. If such heat is excluded, then nature probably does not mind being “quantum” at any size.
If this is the case, with advanced technology we could place large objects, perhaps even conscious beings, in quantum states.
Physicists do not know what a mechanism to prevent large-scale quantum superpositions would look like. According to some, this is an unknown cosmological field. Others suspect that gravity may have something to do with it.
This year’s Nobel Prize winner in physics, Roger Penrose, believes that this may be a consequence of the consciousness of living beings.
Pursuit of small movements
For the past decade or so, physicists have been frantically searching for traces of heat that would indicate a disturbance in wave function.
To understand this, we will need a method that can suppress (as perfectly as possible) all other sources of “excess” heat that can interfere with accurate measurement.
We should also control an effect called a quantum “discount” in which the act of observation itself creates heat.
In our study, we have formulated such an experiment that could reveal whether spatial superposition is possible for large objects. The best experiments so far have failed to achieve this.
Finding the answer with small rays that vibrate
Our experiment would use resonators at much higher frequencies than were used. This would eliminate the heat problem from the refrigerator itself.
As in previous experiments, we will need to use a refrigerator at 0.01 degrees Kelvin above absolute zero. (Absolute zero is theoretically the lowest possible temperature).
With this combination of very low temperatures and very high frequencies, the vibrations in the resonators undergo a process called “Bose condensation”.
You can imagine this because the resonator becomes so hard frozen that the heat from the refrigerator can’t move it, even a little.
We would also use a different measurement strategy that does not consider the motion of the resonator at all, but rather the amount of energy it has. This method would also greatly suppress the heat in the back.
But how would we do that?
Single particles of light would enter the resonator and bounce back and forth several million times, absorbing excess energy. Eventually, they would leave the resonator, carrying the excess energy.
By measuring the energy of the light particles that come out, we could determine if there is heat in the resonator.
If there was heat, it would mean that an unknown source (for which we did not control) had disrupted the wave function. And that would mean that it is impossible for superposition to happen on a large scale.
Is everything quantum?
The experiment we offer is challenging. This is not something you can set up casually on a Sunday afternoon. It can take years of development, millions of dollars and a whole bunch of experienced experimental physicists.
Nevertheless, it can answer one of the most fascinating questions about our reality: is everything quantum? So, we certainly think it’s worth the effort.
As for putting a person or a cat in quantum superposition – there really is no way to know how that would affect this creature.
Fortunately, this is an issue we should not think about for the time being.
2000 atoms in two places at once: A new record in quantum superposition
Provided by The Conversation
This article is republished by The Conversation under a Creative Commons license. Read the original article.
Quote: Can Schrödinger’s cat exist in real life? Our study may soon provide an answer (2020, October 15), retrieved on October 15, 2020 from https://phys.org/news/2020-10-schrdinger-cat-real-life.html
This document is subject to copyright. Except for any fair transaction for the purpose of private examination or research, no part may be reproduced without written permission. The content is provided for informational purposes only.