Physicists Create Biggest-Ever Schrodinger's Cat (scientificamerican.com) 56
Researchers in the Hybrid Quantum Systems Group at the Swiss Federal Institute of Technology in Zurich have put a sapphire crystal weighing 16 micrograms in a quantum-mechanical superposition of two vibrational states. The researchers "excited the crystal into vibrations such that its atoms oscillated back and forth simultaneously and in two opposite directions -- putting the entire crystal in what is known as a state of quantum superposition," reports Scientific American. From the report: As the research group reports in Science, this condition is much like that of the cat in the famous thought experiment of physicist Erwin Schrodinger. In Schrodinger's quantum-mechanical scenario, a cat is simultaneously alive and dead, depending on the decay of an atom that releases a vial of poison. The sapphire crystal in the new experiment has been put in the macroscopic equivalent of that "cat state." Such states can help scientists fathom how and why the laws of the quantum world transition into the rules of classical physics for larger objects.
To get the sapphire, which consists of about 10^17 atoms, to behave like a quantum-mechanical object, the research group set it to oscillate and coupled it to a superconducting circuit. (In the terms of the original thought experiment, the sapphire was the cat, and the superconducting circuit was the decaying atom.) The circuit was used as a qubit, or bit of quantum information that is simultaneously in the states "0" and "1." The circuit's superposition was then transferred to the oscillation of the crystal. Thus, the atoms in the crystal could move in two directions at the same time -- for example, up and down -- just as Schrodinger's cat is dead and alive at the same time. Importantly, the distance between these two states (alive and dead or up and down) had to be greater than the distance ascribed to the quantum uncertainty principle, which the ETH Zurich scientists confirmed. Using the superconducting qubit, the researchers succeeded in determining the distance between the crystal's two vibrational states. At about two billionths of a nanometer, it's tiny -- but still large enough to distinguish those two states from each other beyond doubt.
These findings have "pushed the envelope on what can be considered quantum mechanical in an actual lab experiment," says Shlomi Kotler, a physicist who studies quantum mechanical circuits at the Hebrew University of Jerusalem. Kotler did not participate in the study. [...] Kotler notes that finding larger cat states is a way of "stretching the limit" of observed quantum-mechanical objects -- in this case, by demonstrating that something as massive as 16 micrograms can exist in this state. (Though, to be clear, 16 micrograms is still microscopic.)
To get the sapphire, which consists of about 10^17 atoms, to behave like a quantum-mechanical object, the research group set it to oscillate and coupled it to a superconducting circuit. (In the terms of the original thought experiment, the sapphire was the cat, and the superconducting circuit was the decaying atom.) The circuit was used as a qubit, or bit of quantum information that is simultaneously in the states "0" and "1." The circuit's superposition was then transferred to the oscillation of the crystal. Thus, the atoms in the crystal could move in two directions at the same time -- for example, up and down -- just as Schrodinger's cat is dead and alive at the same time. Importantly, the distance between these two states (alive and dead or up and down) had to be greater than the distance ascribed to the quantum uncertainty principle, which the ETH Zurich scientists confirmed. Using the superconducting qubit, the researchers succeeded in determining the distance between the crystal's two vibrational states. At about two billionths of a nanometer, it's tiny -- but still large enough to distinguish those two states from each other beyond doubt.
These findings have "pushed the envelope on what can be considered quantum mechanical in an actual lab experiment," says Shlomi Kotler, a physicist who studies quantum mechanical circuits at the Hebrew University of Jerusalem. Kotler did not participate in the study. [...] Kotler notes that finding larger cat states is a way of "stretching the limit" of observed quantum-mechanical objects -- in this case, by demonstrating that something as massive as 16 micrograms can exist in this state. (Though, to be clear, 16 micrograms is still microscopic.)
The Stranger (Score:1)
I'm alive
I'm dead
SchrÃdinger intelligence state (Score:5, Funny)
Re: (Score:1)
I wonder how exactly then can know that the crystal is in a superposition state. It has to be isolated from the environment, otherwise the wave function collapses. So you can't exactly watch it, because as soon as you try to determine the vibration state it picks one of the two. How can they tell that it's in superposition, then? Do they shine a laser on it that can reflect in two different ways depending on the vibration of the crystal and let those two paths interfere with each other like in the double sl
Helping and not helping at the same (Score:5, Funny)
Things like this always make me think of this exchange from The Good Place [wikipedia.org] (S1e6) What We Owe to Each Other [fandom.com]:
Eleanor: I need to figure out a way both help him [Michael] and not help him, at the same time.
Chidi: That's literally not possible.
Eleanor: Oh, really? I once posed as a hot prom date for my cousin, both helping him and later - according to his therapist - not helping him.
Re: Helping and not helping at the same (Score:2)
Huh? How is that special? (Score:2)
Bear in mind I don't have a clue about anything quantum and am attempting to learn something here.
What exactly is special about being able to measure the distance of oscillation that makes the sapphire become the cat. I mean how is that special from just any other distance measurement?
A quantum tale (Score:5, Informative)
Rather than talk about spin or vibration, I like to use quantum position. The bomb detector experiment [wikipedia.org] measures the position of a photon down one of two paths in the setup and illustrates quantum weirdness.
The first mirror (SW, South-West mirror) is semi-silvered, with a 50% reflection coefficient. The NE (NorthEast) mirror is also silvered, with a 50% reflection. The other two mirrors (NW, SE) are regular mirrors with 100% reflection.
Position is a probability wave. A wave at any specific frequency can be represented as an amplitude of sin() plus an amplitude of cos(), which together add to the make a specific frequency but at a specific phase. A probability wave says that the probability of finding a photon is the square of the wave value, which is sin()^2 plus cos()^2, which add to 1.0 to make a probability.
We run the experiment from the link above using a single photon at a time. We can tell it's only a single photon because we can count the clicks in the detector and only run the experiment if the clucks are coming slowly - less than one a second, for instance. If the clicks are coming too fast our light source is too bright (emitting too many photons at once), there could be more than 1 photon in the path at one time, and so we hold a glass plate over a candle to get some lamp black and put that between the light source and the 1st mirror to dim the light a little, and repeat until we're reliably getting only 1 photon per second.
Position is a probability wave, and what the SW mirror (semi-silvered) actually does is split the probability into sin() and cos() components. The sin() gets reflected, the cos() goes through. It doesn't sometimes reflect and sometimes not reflect - it splits the position of *every* photon that it encounters.
Now lets slow system a lot and imagine a little LED associated with the photon (thought problem - right?). The sin() goes the north->east path while the cos() goes the east->north path. Position is the superposition of (the square of) these two, so we see the LED get bright in one path, then dim while it gets bright in the *other* path, then dims and gets bright in the 1st path 1/2 wavelength further along, then that dims and the bright dot is seen 1/2 wavelength further along in the other path... and back and forth one path to the other until the paths meet at the NE corner.
Position alternates from one path to the other. Actually, the *probability* of the position is what alternates, and we can imagine intermediate values where the LED is 25% bright in one path and 75% bright in the other, representing the idea that if you reached in and grabbed it you would have 75% chance of getting the photon energy in the one path. And you have a 25% chance of missing.
Now consider the famous bomb detector experiment. The bomb has a window with a detector installed or no detector installed (defective bomb). If a photon hits the detector, the bomb goes off.
If there is no detector installed, the photon is unimpeded and everything works as described.
If there is a detector the window is opaque and there is a chance that the LED is on at the point of the detector, which means the photon position is "there" at the detector, the detector receives the energy of the photon, and the bomb goes off.
However, if the detector is placed at the point where the LED is off, the photon is "not there" at the detector, the detector will receive no energy from the photon and the bomb will not go off. Overall, accounting for the intermediate values, the detector has a 50% chance of intercepting the photon.
But here's the rub: The position of the photon is described both by where it is and where it isn't. If you catch the photon where it is then fine - you collapse the waveform and receive the photon energy. If the photon is *not* where you are looking, that also collapses the waveform and the photon is locked in the other position. The photon was detected "not i
Re: (Score:2)
That's a big write-up for a forum posting!
I still don't see how that relates to measuring the size of an oscillation.
One idea I've had for an equivalence is like how traditional AM/FM modulators functioned. Which was to modify the carrier amplitude/frequency. The actual instantaneous amplitude of the carrier was not a known. The carrier oscillated much faster than the modulation circuits.
Re: (Score:2)
Get Better Equipment (Score:2)
And get back to me. Just because you can't measure the change fast enough doesn't mean it is happening or in this case not happening. Or vice versa. Or at the same time. Yea.
Re: Get Better Equipment (Score:1)
Are you just afraid that your neat little consistent world fairy tale is being exploded before your very eyes, and you are passing through the early stages of grief about losing control of the "consistency" narrative?
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Meow.
Re: (Score:1)
You mean "what is a woman"?
Our modern "the edges get fuzzy if you look too close" has lead to a lot of claiming that distinct states don't exist.
extrapolate a bit and ... (Score:2)
Relativistic Quantum (Score:5, Informative)
We create such a state between two locations for one object, then "open the box" to see where it is. Repeat until it's over there instead of here.
Sapphire crystal (Score:2)
"All irregularities will be handled by the forces controlling each dimension. Transuranic heavy elements may not be used where there is life. Medium atomic weights are available: Gold, Lead, Copper, Jet, Diamond, Radium, Sapphire, Silver and Steel.
Sapphire and Steel have been assigned."
Biggest Ever Cat (Score:2)
The good news: The cat is alive. [i.redd.it]
The bad news: You have a 50-50 chance of surviving.
Please enough with the cats already (Score:1)
I wish they would have focused on the science and dispensed with the stupid cats. I'm sick and tired of hearing about Schrodinger's cat.
The switch that kills the cat or not requires a decision e.g. collapse of the wave function to work. The damn cat itself is obviously never in a frigging superposition of dead or alive. I wish people would stop with the dopey mysticism.
Re: (Score:2)
The damn cat itself is obviously never in a frigging superposition of dead or alive. I wish people would stop with the dopey mysticism.
This was precisely Schrödinger's point. Unfortunately, a large number of people who should know better latched on to the cat and forgot the dopey.
Re: (Score:2)
Except this news is about the largest object fitting this description ever made, you can't actually do it with a cat.
Re: (Score:2)
Thank you. The whole thing (including Shroedinger) is quite silly. Change the cat's "is" situation to "either or", emphasize the above experiment's "could", and it might make a wee bit of sense. Otherwise ... totally asinine: nothing can be here _and_ there, moving up _and_ down. It's a contradiction of terms, a misuse of the language, and certainly not logical _or_ science. It all ranks right up there with some of the more asinine religious discussions of Medieval times, like how many angels can danc
Newsflash! (Score:2)
SchrÃdinger's cat found half-alive; quantum theory a mistake!
Schrödinger's experiment is pointless (Score:3)
Quite frankly, if you lock a cat into a box, you can very easily figure out whether the cat inside the box is alive without opening it by the noise coming from the box, not to mention that, depending on the relative sizes of box and cat, it would move about quite a bit if there is a very alive and very pissed cat in side.
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Vibrating both ways at once? (Score:2)
Re: (Score:2)
THANK YOU. Yes this really bugged me. TFA says, "Just as a cat cannot be alive and dead at the same time, a crystal cannot vibrate up and down at the same time. " Obviously oscillation and "vibrate up and down" seem to mean the same thing so you are just left gasping. I only have access to the abstract of the actual paper but it says, "We control the size and phase of the superpositions and investigate their decoherence dynamics." That makes more sense. Not a physicist, so I cannot tell whether here "phase"
Re: (Score:3)
Re: (Score:2)
My thoughts exactly. ... uhm ... scratch that thought.
Kind'a like claiming to be both at work and at home at the same t
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Schrodinger was against the idea of superposition (Score:2)
It was to point out the non intuitive nature of quantum superposition that Schrodinger came up with the cat thought experiment, not support superposition.
https://www.wondriumdaily.com/... [wondriumdaily.com]
Disappointment (Score:1)
... 16 micrograms is still microscopic (Score:2)
No.
Volume = Mass / Density
16 micrograms is only microscopic at certain densities. There could exist planetary-scale structures whose masses are 16 micrograms.
Related experiment (Score:2)
Slide both ends ever so slightly together, and it'll bow (buckle) either up or down. The bowing/deflection is easily measured with a laser or AFM probe. These are bistable states: once you bowing downwards, you c